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  Subjects -> ENGINEERING (Total: 2415 journals)
    - CHEMICAL ENGINEERING (206 journals)
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    - ENGINEERING (1273 journals)
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ENGINEERING (1273 journals)                  1 2 3 4 5 6 7 | Last

Showing 1 - 200 of 1205 Journals sorted alphabetically
3 Biotech     Open Access   (Followers: 8)
3D Research     Hybrid Journal   (Followers: 21)
AAPG Bulletin     Hybrid Journal   (Followers: 8)
AASRI Procedia     Open Access   (Followers: 15)
Abstract and Applied Analysis     Open Access   (Followers: 3)
Aceh International Journal of Science and Technology     Open Access   (Followers: 3)
ACS Nano     Hybrid Journal   (Followers: 290)
Acta Geotechnica     Hybrid Journal   (Followers: 7)
Acta Metallurgica Sinica (English Letters)     Hybrid Journal   (Followers: 7)
Acta Polytechnica : Journal of Advanced Engineering     Open Access   (Followers: 3)
Acta Scientiarum. Technology     Open Access   (Followers: 3)
Acta Universitatis Cibiniensis. Technical Series     Open Access  
Active and Passive Electronic Components     Open Access   (Followers: 7)
Adaptive Behavior     Hybrid Journal   (Followers: 11)
Adıyaman Üniversitesi Mühendislik Bilimleri Dergisi     Open Access  
Adsorption     Hybrid Journal   (Followers: 4)
Advanced Engineering Forum     Full-text available via subscription   (Followers: 8)
Advanced Journal of Graduate Research     Open Access  
Advanced Science     Open Access   (Followers: 5)
Advanced Science Focus     Free   (Followers: 5)
Advanced Science Letters     Full-text available via subscription   (Followers: 10)
Advanced Science, Engineering and Medicine     Partially Free   (Followers: 7)
Advanced Synthesis & Catalysis     Hybrid Journal   (Followers: 17)
Advances in Calculus of Variations     Hybrid Journal   (Followers: 4)
Advances in Catalysis     Full-text available via subscription   (Followers: 5)
Advances in Complex Systems     Hybrid Journal   (Followers: 7)
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Advances in Fuel Cells     Full-text available via subscription   (Followers: 16)
Advances in Fuzzy Systems     Open Access   (Followers: 5)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 14)
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Advances in Remote Sensing     Open Access   (Followers: 49)
Advances in Science and Research (ASR)     Open Access   (Followers: 6)
Aerobiologia     Hybrid Journal   (Followers: 3)
African Journal of Science, Technology, Innovation and Development     Hybrid Journal   (Followers: 6)
AIChE Journal     Hybrid Journal   (Followers: 35)
Ain Shams Engineering Journal     Open Access   (Followers: 5)
Akademik Platform Mühendislik ve Fen Bilimleri Dergisi     Open Access   (Followers: 1)
Al-Nahrain Journal for Engineering Sciences     Open Access  
Alexandria Engineering Journal     Open Access   (Followers: 1)
AMB Express     Open Access   (Followers: 1)
American Journal of Applied Sciences     Open Access   (Followers: 26)
American Journal of Engineering and Applied Sciences     Open Access   (Followers: 10)
American Journal of Engineering Education     Open Access   (Followers: 11)
American Journal of Environmental Engineering     Open Access   (Followers: 16)
American Journal of Industrial and Business Management     Open Access   (Followers: 24)
Annals of Combinatorics     Hybrid Journal   (Followers: 4)
Annals of Pure and Applied Logic     Open Access   (Followers: 3)
Annals of Regional Science     Hybrid Journal   (Followers: 7)
Annals of Science     Hybrid Journal   (Followers: 7)
Antarctic Science     Hybrid Journal   (Followers: 1)
Applicable Algebra in Engineering, Communication and Computing     Hybrid Journal   (Followers: 2)
Applicable Analysis: An International Journal     Hybrid Journal   (Followers: 1)
Applied Catalysis A: General     Hybrid Journal   (Followers: 6)
Applied Catalysis B: Environmental     Hybrid Journal   (Followers: 18)
Applied Clay Science     Hybrid Journal   (Followers: 6)
Applied Computational Intelligence and Soft Computing     Open Access   (Followers: 12)
Applied Magnetic Resonance     Hybrid Journal   (Followers: 4)
Applied Nanoscience     Open Access   (Followers: 8)
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Applied Numerical Mathematics     Hybrid Journal   (Followers: 5)
Applied Physics Research     Open Access   (Followers: 5)
Applied Sciences     Open Access   (Followers: 3)
Applied Spatial Analysis and Policy     Hybrid Journal   (Followers: 5)
Arab Journal of Basic and Applied Sciences     Open Access  
Arabian Journal for Science and Engineering     Hybrid Journal   (Followers: 5)
Archives of Computational Methods in Engineering     Hybrid Journal   (Followers: 5)
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Archives of Thermodynamics     Open Access   (Followers: 9)
Arkiv för Matematik     Hybrid Journal   (Followers: 1)
ASEE Prism     Full-text available via subscription   (Followers: 3)
Asia-Pacific Journal of Science and Technology     Open Access  
Asian Engineering Review     Open Access  
Asian Journal of Applied Science and Engineering     Open Access   (Followers: 1)
Asian Journal of Applied Sciences     Open Access   (Followers: 2)
Asian Journal of Biotechnology     Open Access   (Followers: 9)
Asian Journal of Control     Hybrid Journal   (Followers: 1)
Asian Journal of Current Engineering & Maths     Open Access  
Asian Journal of Technology Innovation     Hybrid Journal   (Followers: 8)
Assembly Automation     Hybrid Journal   (Followers: 2)
at - Automatisierungstechnik     Hybrid Journal   (Followers: 1)
ATZagenda     Hybrid Journal  
ATZextra worldwide     Hybrid Journal  
Australasian Physical & Engineering Sciences in Medicine     Hybrid Journal   (Followers: 1)
Australian Journal of Multi-Disciplinary Engineering     Full-text available via subscription   (Followers: 2)
Autonomous Mental Development, IEEE Transactions on     Hybrid Journal   (Followers: 9)
Avances en Ciencias e Ingeniería     Open Access  
Balkan Region Conference on Engineering and Business Education     Open Access   (Followers: 1)
Bangladesh Journal of Scientific and Industrial Research     Open Access  
Basin Research     Hybrid Journal   (Followers: 5)
Batteries     Open Access   (Followers: 6)
Bautechnik     Hybrid Journal   (Followers: 1)
Bell Labs Technical Journal     Hybrid Journal   (Followers: 28)
Beni-Suef University Journal of Basic and Applied Sciences     Open Access   (Followers: 4)
BER : Manufacturing Survey : Full Survey     Full-text available via subscription   (Followers: 1)
BER : Motor Trade Survey     Full-text available via subscription  
BER : Retail Sector Survey     Full-text available via subscription   (Followers: 1)
BER : Retail Survey : Full Survey     Full-text available via subscription   (Followers: 1)
BER : Survey of Business Conditions in Manufacturing : An Executive Summary     Full-text available via subscription   (Followers: 3)
BER : Survey of Business Conditions in Retail : An Executive Summary     Full-text available via subscription   (Followers: 3)
Beyond : Undergraduate Research Journal     Open Access  
Bhakti Persada : Jurnal Aplikasi IPTEKS     Open Access  
Bharatiya Vaigyanik evam Audyogik Anusandhan Patrika (BVAAP)     Open Access   (Followers: 1)
Bilge International Journal of Science and Technology Research     Open Access  
Biofuels Engineering     Open Access   (Followers: 1)
Biointerphases     Open Access   (Followers: 1)
Biomaterials Science     Full-text available via subscription   (Followers: 11)
Biomedical Engineering     Hybrid Journal   (Followers: 15)
Biomedical Engineering     Hybrid Journal   (Followers: 1)
Biomedical Engineering and Computational Biology     Open Access   (Followers: 13)
Biomedical Engineering Letters     Hybrid Journal   (Followers: 5)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 21)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 37)
Biomedical Engineering: Applications, Basis and Communications     Hybrid Journal   (Followers: 5)
Biomedical Microdevices     Hybrid Journal   (Followers: 8)
Biomedical Science and Engineering     Open Access   (Followers: 4)
Biomicrofluidics     Open Access   (Followers: 4)
BioNanoMaterials     Open Access   (Followers: 2)
Biotechnology Progress     Hybrid Journal   (Followers: 40)
Bitlis Eren University Journal of Science and Technology     Open Access  
Boletin Cientifico Tecnico INIMET     Open Access  
Botswana Journal of Technology     Full-text available via subscription   (Followers: 1)
Boundary Value Problems     Open Access   (Followers: 1)
Brazilian Journal of Science and Technology     Open Access   (Followers: 2)
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 12)
Bulletin of Canadian Petroleum Geology     Full-text available via subscription   (Followers: 13)
Bulletin of Engineering Geology and the Environment     Hybrid Journal   (Followers: 14)
Bulletin of the Crimean Astrophysical Observatory     Hybrid Journal  
Cahiers Droit, Sciences & Technologies     Open Access  
Calphad     Hybrid Journal   (Followers: 2)
Canadian Geotechnical Journal     Hybrid Journal   (Followers: 31)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 44)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 6)
Case Studies in Thermal Engineering     Open Access   (Followers: 6)
Catalysis Communications     Hybrid Journal   (Followers: 6)
Catalysis Letters     Hybrid Journal   (Followers: 2)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 7)
Catalysis Science and Technology     Free   (Followers: 8)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 3)
Catalysis Today     Hybrid Journal   (Followers: 7)
CEAS Space Journal     Hybrid Journal   (Followers: 2)
Cellular and Molecular Neurobiology     Hybrid Journal   (Followers: 3)
Central European Journal of Engineering     Hybrid Journal  
Chaos : An Interdisciplinary Journal of Nonlinear Science     Hybrid Journal   (Followers: 2)
Chaos, Solitons & Fractals     Hybrid Journal   (Followers: 3)
Chinese Journal of Catalysis     Full-text available via subscription   (Followers: 2)
Chinese Journal of Engineering     Open Access   (Followers: 2)
Chinese Science Bulletin     Open Access   (Followers: 1)
Ciencia e Ingenieria Neogranadina     Open Access  
Ciencia en su PC     Open Access   (Followers: 1)
Ciencia y Tecnología     Open Access  
Ciencias Holguin     Open Access   (Followers: 3)
CienciaUAT     Open Access   (Followers: 1)
Cientifica     Open Access  
CIRP Annals - Manufacturing Technology     Full-text available via subscription   (Followers: 11)
CIRP Journal of Manufacturing Science and Technology     Full-text available via subscription   (Followers: 13)
City, Culture and Society     Hybrid Journal   (Followers: 22)
Clay Minerals     Full-text available via subscription   (Followers: 10)
Clean Air Journal     Full-text available via subscription   (Followers: 1)
Clinical Science     Hybrid Journal   (Followers: 9)
Coal Science and Technology     Full-text available via subscription   (Followers: 3)
Coastal Engineering     Hybrid Journal   (Followers: 11)
Coastal Engineering Journal     Hybrid Journal   (Followers: 6)
Coatings     Open Access   (Followers: 4)
Cogent Engineering     Open Access   (Followers: 3)
Cognitive Computation     Hybrid Journal   (Followers: 4)
Color Research & Application     Hybrid Journal   (Followers: 3)
COMBINATORICA     Hybrid Journal  
Combustion Theory and Modelling     Hybrid Journal   (Followers: 14)
Combustion, Explosion, and Shock Waves     Hybrid Journal   (Followers: 15)
Communications Engineer     Hybrid Journal   (Followers: 1)
Communications in Information Science and Management Engineering     Open Access   (Followers: 4)
Communications in Numerical Methods in Engineering     Hybrid Journal   (Followers: 2)
Components, Packaging and Manufacturing Technology, IEEE Transactions on     Hybrid Journal   (Followers: 28)
Composite Interfaces     Hybrid Journal   (Followers: 7)
Composite Structures     Hybrid Journal   (Followers: 290)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 222)
Composites Part B : Engineering     Hybrid Journal   (Followers: 260)
Composites Science and Technology     Hybrid Journal   (Followers: 200)
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Computers and Electronics in Agriculture     Hybrid Journal   (Followers: 5)
Computers and Geotechnics     Hybrid Journal   (Followers: 11)
Computing and Visualization in Science     Hybrid Journal   (Followers: 7)
Computing in Science & Engineering     Full-text available via subscription   (Followers: 34)

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Journal Cover
Catalysis Today
Journal Prestige (SJR): 1.347
Citation Impact (citeScore): 5
Number of Followers: 7  
 
  Hybrid Journal Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0920-5861
Published by Elsevier Homepage  [3161 journals]
  • Ab initio study of ligand dissociation/exchange and the hydrogen
           production process of the Co(dmgH)2(py)Cl cobaloxime in the
           acetonitrile-water solvent
    • Abstract: Publication date: 15 September 2018Source: Catalysis Today, Volume 314Author(s): Jinfan Chen, Patrick H.-L. SitDensity functional theory (DFT) calculations and Car-Parrinello molecular dynamics (CPMD) simulations in the explicit acetonitrile-water solvent were carried out to study the ligand dissociation/exchange process and hydrogen production pathway of a common cobaloxime complex, Co(dmgH)2(py)Cl (py = pyridine). Our results show that the axial Cl− is readily replaced by a water molecule which is a key step for the subsequent proton transfer in the hydrogen production cycle. Moreover, the py ligand also dissociates readily from the complex at a later stage. The alternate two electrons and two protons addition pathway was identified to be the favorable one for hydrogen production. The rate determining step of the hydrogen production by Co(dmgH)2(py)Cl is the first protonation of the Co ion, which competes with the proton transfer to the O of the side group of the complex.Graphical abstractGraphical abstract for this article
       
  • Research on inhibitors and hindered groups in ultra-deep
           hydrodesulfurization based on density functional theory
    • Abstract: Publication date: 15 September 2018Source: Catalysis Today, Volume 314Author(s): Peng Zhang, Qichen Zhao, Jingjun Liu, Bolun YangHydrodesulfurization (HDS) of thiophenic sulfur with hindered groups in the presence of inhibitors (nitrogen compounds and H2S) is vital in achieving ultralow sulfur level in gasoline. The objective of this research was to investigate effects of inhibitors and hindered groups on ultra-deep HDS of thiophenic sulfur on Ni2P catalyst in a mechanistic perspective. Density functional calculations were used to investigate adsorption of inhibitors and sulfur compounds combined with thermodynamic analysis. Activation mechanism of sulfur compounds was studied using partial density of state (PDOS) and electron density difference analysis. All species preferred to be adsorbed at the three-fold hollow Ni site and its vicinity. Inhibitors had larger adsorption energy and constant than sulfur compounds. Co-adsorption of thiophene and inhibitors weakened the adsorption of thiophene. Population analysis revealed that some electrons moved to higher energy states suggesting activation. Sulfur compounds adsorbed to Ni2P surface mainly through Ni-S bonds exhibiting characteristics of covalent bonding, originating from the overlapping of 3p states of S and 3d states of Ni. Inhibitors show tendencies to adsorb to Ni2P surface over sulfur compounds. Hindered groups impede adsorption of sulfur compounds and weaken the interaction between sulfur compounds and surface mainly due to steric hinderance.Graphical abstractGraphical abstract for this article
       
  • Characterization of supported Cu-Zn/graphene aerogel catalyst for direct
           CO2 hydrogenation to methanol: Effect of hydrothermal temperature on
           graphene aerogel synthesis
    • Abstract: Publication date: 15 September 2018Source: Catalysis Today, Volume 314Author(s): Varisara Deerattrakul, Pralachoak Puengampholsrisook, Wanwisa Limphirat, Paisan KongkachuichayReduced graphene oxide aerogel (rGOae) was synthesized via hydrothermal reduction and following freeze-drying method. The as-prepared material was then used as a novel support of Cu-Zn/rGOae catalyst for the direct CO2 hydrogenation to methanol. Moreover, in situ X-ray absorption near-edge structure (XANES) spectroscopy was applied to evaluate the oxidation state of the Cu and Zn species during the H2 reduction process at 350 °C with a holding time of 90 min. The effects of the hydrothermal reduction temperature of rGOae support and Cu-Zn metal loading contents were investigated. Interestingly, the hydrothermal reduction at 140 °C provided the highest surface area (458 m2 g−1), and 15wt%Cu-Zn/rGOae catalyst achieved the highest methanol production (94.53 mgMeOH gcat−1 h−1) at a reaction temperature of 250 °C and pressure of 15 bar.Graphical abstractGraphical abstract for this article
       
  • Highly efficient copper-doped manganese oxide nanorod catalysts derived
           from CuMnO hierarchical nanowire for catalytic combustion of VOCs
    • Abstract: Publication date: 15 September 2018Source: Catalysis Today, Volume 314Author(s): J. Hu, W.B. Li, R.F. LiuCopper-doped manganese oxide nanorod catalysts with various Cu/Mn molar ratios have been prepared for catalytic combustion of Volatile organic compounds (VOCs). The effects of Cu/Mn ratio and calcination temperatures on catalytic performance were investigated. It turned out that the Cu1Mn1-500 sample exhibited the best catalytic combustion performance, to remove toluene at a temperature of 214 °C over 120 h without a significant decrease in toluene conversion. XRD, SEM, HRTEM, XPS were carried out to explore the physicochemical properties of catalysts, and the results demonstrated that doping copper into manganese oxides can contribute to rich oxygen vacancies, high redox capability, and hence increase the catalytic activity. In addition, both the large surface area and high crystallization of the obtained nanorod catalysts are also helpful for the high activity and stability of these copper-manganese mixed metal oxide catalysts. Furthermore, the presence of water vapor had little inhibition effect on the catalytic activity under the reaction condition.Graphical abstractGraphical abstract for this article
       
  • Catalytic activity of an economically sustainable fly-ash-metal-organic-
           framework composite towards biomass valorization
    • Abstract: Publication date: 15 September 2018Source: Catalysis Today, Volume 314Author(s): Amrita Chatterjee, Xijun Hu, Frank Leung-Yuk LamLow thermal stability and insufficient Brønsted acidity are the deficiencies of conventional metal-organic-frameworks (MOFs), which would greatly limit their applications particularly for high temperature and pressure reactions such as dehydration of carbohydrates. This work has successfully demonstrated the development of a composite of MOF and activated fly ash, and their catalytic application in the xylose-to-furfural dehydration process. The composite is capable of maintaining high stability under severe hydrothermal conditions and even in the acidic medium. In addition, the composite shows its excellent catalytic performance for ten consecutive reaction cycles, which is much better than the bare MOF catalyst, MIL-101 (Cr), obtaining the furfural yield and selectivity of 71% and 80%, respectively. It is proposed that such catalytic activity is mainly attributed to the mutual contribution from the Cr atoms of MIL-101 (Cr) and hydroxyl groups of activated fly ash, acting as Lewis acid centers and Brønsted acid sites, respectively. Besides, the effect of salt concentration on the efficiency of xylose conversion has been studied. The product yield can be enhanced to 78% in the presence of trace amount of sodium chloride solution (35 ppt). This provides a promising direction towards the applications when seawater is used as the reaction media. In summary, the work shows that the incorporation of fly ash as the composite material not only reduces the cost of synthesis, but also mitigates the fly ash disposal problems to some extent.Graphical abstractGraphical abstract for this article
       
  • Towards a recyclable MOF catalyst for efficient production of furfural
    • Abstract: Publication date: 15 September 2018Source: Catalysis Today, Volume 314Author(s): Amrita Chatterjee, Xijun Hu, Frank Leung-Yuk LamMetal-organic-frameworks (MOFs) possess the qualities of being a suitable catalyst with its high surface area, tunable functional groups and numerous uncoordinated active sites. However, low hydrothermal stability and poor resistance to acidic medium hinder its usage as catalysts in dehydration reactions to produce biofuels or fine chemicals. Typically, the Lewis acidic chromium sites of MIL-101 (Cr) enable catalysis of the xylose dehydration reaction up to 49% of furfural yield at 170 °C. Unfortunately, the durability of pristine MOF is still questionable, which can only be recovered for 4 times. This work reports a way to improve hydrothermal stability of MIL-101 (Cr) by functionalizing it with hydrophobic octadecyltrichlorosilane (OTS) without any significant negative impacts on its catalytic activity. The coated MOF, MIL-OTS-0.5, provides a yield of 56% with high durability of catalytic activity up to 8 reaction cycles. The confinement of the active sites within silane groups facilitates the MIL-OTS to retain their structure and properties over pristine MIL-101 (Cr). Moreover, addition of 35 ppt NaCl in the aqueous phase in presence of MIL-OTS-0.5 enhances the furfural yield up to 62.6%.Graphical abstractGraphical abstract for this article
       
  • Synthesis of CuO catalyst derived from HKUST-1 temple for the
           low-temperature NH3-SCR process
    • Abstract: Publication date: 15 September 2018Source: Catalysis Today, Volume 314Author(s): Bo Peng, Chao Feng, Shanshan Liu, Runduo ZhangCuO catalyst was prepared from HKUST-1 temple through a pyrolysis process, noted as CuO-p. Its morphology with octahedral shape was verified to be inherited from the HKUST-1 and however essentially difference with CuO-c prepared by coprecipitation method. Moreover, CuO-p (15.4 m2/g) obtained by HKUST-1 pyrolysis has a bigger surface area than that (CuO-c, 3.4 m2/g) obtained by coprecipitation. The CuO samples and HKUST-1 were tested for low-temperature selective catalytic reduction (SCR) of NO with NH3 as reducing agent. The CuO-p catalyst derived from HKUST-1 exhibited the superior deNOx activity with respect to CuO-c. The further calcination at 600 °C under an N2 atmosphere is beneficial for improving the specific surface area and achieving an ideal SCR performance (TOF of 3.45 × 10−5 s−1 and ∼100% selectivity towards N2 at 270 °C). This work expands the potential applications of MOFs as catalysts.Graphical abstractGraphical abstract for this article
       
  • Sustainable production of methanol from CO2 over 10Cu-10Fe/ZSM-5 catalyst
           in a magnetic field-assisted packed bed reactor
    • Abstract: Publication date: 15 September 2018Source: Catalysis Today, Volume 314Author(s): Chuleehat Sriakkarin, Wasakon Umchoo, Waleeporn Donphai, Yingyot Poo-arporn, Metta ChareonpanichIn this work, with an attempt to improve both economic and ecological aspects towards green production of methanol, an external magnetic field was equipped with a catalytic packed-bed reactor for selective production of methanol through CO2 hydrogenation over Cu and Fe loaded on microporous ZSM-5 zeolite. The effects of reaction temperatures (180–260 °C) and CO2/H2 molar ratios (1:1–1:4) on selective methanol production were investigated under magnetic field direction of North-to-South (or N–S) at a flux intensity of 27.7 mT, and compared to those obtained without the magnetic field (conventional process). It was found that with the external magnetic field, the outstanding improvement in catalytic activity and selectivity of CO2 hydrogenation was observed. The highest CO2 conversion over 10Cu-10Fe/ZSM-5 catalyst was obtained at the CO2/H2 molar ratio of 1:3 under an external magnetic field. In addition, the alcohol production favored a lower reaction temperature. Using the external magnetic field, the CO2 conversion and selectivity to methanol were increased by factors of 1.7 and 2.24 at 220 °C, respectively. The application of magnetic field therefore helps facilitate CO2 adsorption and leads to selective methanol production, resulting in the opportunities to provide a green and sustainable innovation in chemical and petrochemical processes.Graphical abstractGraphical abstract for this article
       
  • Effect of reaction conditions on methanol to gasoline conversion over
           nanocrystal ZSM-5 zeolite
    • Abstract: Publication date: 15 September 2018Source: Catalysis Today, Volume 314Author(s): Zhijian Wan, Gang (Kevin) Li, Chuanfu Wang, Hong Yang, Dongke ZhangA nanocrystal ZSM-5 zeolite comprising uniform single crystal particles of ∼100 nm in size was synthesised and characterised using XRD, ICP–AES, SEM, TEM, solid state MAS NMR and nitrogen physisorption techniques. The catalytic performance was tested in methanol to gasoline (MTG) conversion with a particular focus on the effect of reaction conditions, namely, temperature from 300 to 450 °C, pressure from 0.1 to 2.0 MPa and WHSV from 1 to 4 h−1. Temperature showed a significant impact. At temperatures ≤350 °C, methanol conversion did not complete while the catalyst was deactivated more rapidly. Increasing temperature to above 375 °C saw complete methanol conversion and durable catalyst activity. Further increasing the reaction temperature to above 400 °C reduced gasoline yield. Pressure mainly affected the product selectivity; a higher pressure led to a lower C1–C4 selectivity but enhanced durene formation. Further increasing pressure also favoured coke formation, leading to faster loss of catalyst activity. Likewise, increasing WHSV reduced C1–C4 selectivity but promoted the formation of durene and coke, resulting in a rapid deactivation of the catalyst. The optimal reaction conditions for this nanocrystal ZSM-5 catalyst in MTG were found to be 375 °C, 1.0 MPa and WHSV of 2 h−1.Graphical abstractGraphical abstract for this article
       
  • Shape-selective FeMnK/Al2O3@Silicalite-2 core-shell catalyst for
           Fischer-Tropsch synthesis to lower olefins
    • Abstract: Publication date: 15 September 2018Source: Catalysis Today, Volume 314Author(s): Hongyu Wang, Jian Wang, Yong Yuan, Qiao Zhao, Xinsheng Teng, Shouying Huang, Xinbin MaA catalyst with a core (FeMnK/Al2O3 powder)-shell (Silicalite-2) structure was successfully synthesized by combination of Ströber method and hydrothermal crystallization method. TEM, XRD, and N2 adsorption techniques demonstrated that the supported catalyst FeMnK/Al2O3 was encapsulated by Silicalite-2 zeolite with microporous structure. After eliminating diffusion limitation by removal of residual amorphous SiO2 with alkaline treatment, the micron-scale zeolite core-shell catalyst exhibited a much higher selectivity of lower olefins with a favorable CO conversion in Fischer-Tropsch synthesis, while the formation of C5+ was greatly restrained because of the confinement effect of S2. Finally, the encapsulated catalyst was found to be highly stable after a long-time running due to the inhibition of carbon deposit. In summary, this preparation method provides us a new clue for the design of highly selective catalyst for Fischer-Tropsch synthesis to lower olefins.Graphical abstractGraphical abstract for this article
       
  • Increasing resolution of selectivity in alkene hydrogenation via diffusion
           length in core-shell MFI zeolite
    • Abstract: Publication date: 15 September 2018Source: Catalysis Today, Volume 314Author(s): Xicheng Jia, Yanghwan Jeong, Hionsuck Baik, Jungkyu Choi, Alex C.K. YipWe designed a core-shell zeolite structure comprises of palladium-deposited ZSM-5 core and silicalite-1 (S-1) shell which favors selectivity towards light olefin in hydrogenation via increased diffusion length. A well designed S-1/Pd/ZSM-5 core-shell structure was prepared via secondary crystallization of S-1 layer on the Pd/ZSM-5 core. The catalytic and selectivity performance of the S-1/Pd/ZSM-5 composite was evaluated in catalytic hydrogenation of alkenes in liquid phase. The synthesized S-1/Pd/ZSM-5 gives a much higher selectivity towards 1-hexene (87%) over cyclohexene (13%) even though both reactants are able to enter the 10-membered ring channels of the core-shell structure. The zeolitic core-shell composite also showed an increasing selectivity towards 1-hexene over 1-heptene as the S-1 layers built up, even though both are linear alkenes with similar kinetic diameter that are accessible to the MFI framework. In this work, we demonstrate a strong correlation between the thickness of the S-1 shell layer and the selectivity towards light olefins due to faster mass transfer rate. The design of the core-shell MFI structure is a new example of how selectivity in a zeolite-catalyzed reaction can be changed and enhanced without relying on typical molecular size exclusion process.Graphical abstractGraphical abstract for this article
       
  • On the synthesis of a hierarchically-structured ZSM-5 zeolite and the
           effect of its physicochemical properties with Cu impregnation on
           cold-start hydrocarbon trap performance
    • Abstract: Publication date: 15 September 2018Source: Catalysis Today, Volume 314Author(s): Heejoong Kim, Eunhee Jang, Yanghwan Jeong, Jinseong Kim, Chun Yong Kang, Chang Hwan Kim, Hionsuck Baik, Kwan-Young Lee, Jungkyu ChoiA hierarchically structured zeolite (self-pillared pentasil; SPP) comprised of MFI nanosheets or lamellae has been synthesized in various Si/Al ratios and mesoporosities. It turns out that a simple removal of ethanol in a synthesis sol resulted in increased mesoporosity, while the additional reduction of water further increased mesoporosity. In addition, we could synthesize the SPP particle with the actual Si/Al ratio as low as ∼23 with a modest mesoporosity. With these hierarchically structured SPP particles, we further conducted copper impregnation on them in order to use as a hydrocarbon (HC) trap. The resulting Cu-impregnated SPPs could not only adsorb HCs in the exit gas stream including water vapor, but also serve as an active oxidizer of HCs. Specifically, Cu-impregnated SPP with an actual Si/Al ratio of ∼22 and medium mesoporosity exhibited very high performance in cold-start trap tests; desirably adsorbing propene and toluene even in the presence of 10 vol% steam, holding them up to higher temperatures (90 °C for propene and 190 °C for toluene), and furthermore, oxidizing the hydrocarbons. The preferred adsorption can be attributed to the larger amount of exchanged Cu2+ ions in SPP particles with a lower Si/Al ratio, while the additional oxidation was due to the CuO particles dispersed on the SPP surface. However, the hydrothermal stability test revealed that the zeolite structure in the Cu-impregnated SPPs was collapsed and transformed into another undesired phase, thus losing the above-mentioned adsorption ability. Nevertheless, the corresponding oxidation performance was well maintained, indicating the robust, active role of the CuO particles.Graphical abstractGraphical abstract for this article
       
  • Chemical transformation of food and beverage waste-derived fructose to
           hydroxymethylfurfural as a value-added product
    • Abstract: Publication date: 15 September 2018Source: Catalysis Today, Volume 314Author(s): Iris K.M. Yu, Khai Lun Ong, Daniel C.W. Tsang, Md Ariful Haque, Tsz Him Kwan, Season S. Chen, Kristiadi Uisan, Sandeep Kulkarni, Carol Sze Ki LinA novel alternative bioconversion and chemical transformation method for valorisation of food and beverage (F&B) waste to hydroxymethylfurfural (HMF) is reported. Solid-to-liquid ratio of 70% was applied to hydrolyse F&B waste by glucoamylase and sucrase to yield a hydrolysate consisted of glucose and fructose. After impurity removal using chromatography columns, the purified hydrolysate was processed by glucose isomerase to produce syrup with a fructose-to-glucose ratio of 1:1. After removal of the residual impurities using ion exchange columns, Simulated Moving Bed system was applied to separate sugars in fructose-glucose syrup. The resultant high-fructose syrup contained 89.0 g/L fructose, which was demonstrated as an ideal feedstock for the synthesis of HMF. By employing a commercial solid acid catalyst (Amberlyst 36), 71 mol% HMF with a high selectivity of 77 mol% was generated from this high-fructose syrup under mild microwave heating at 140 °C within 40 min. The increase in catalyst loading accelerated both HMF formation and HMF-consuming side reactions, underscoring the trade-off between the conversion rate and product selectivity. The solid catalyst can be recovered and successfully reused for four runs with the HMF yield at 70 mol%. An overall conversion yield of 30 g HMF/kg F&B waste was achieved. This work emphasises a novel integration of chemical and biological technologies for selective production of HMF from mixed F&B waste.Graphical abstractGraphical abstract for this article
       
  • Esterification of levulinic acid with ethanol catalyzed by sulfonated
           carbon catalysts: Promotional effects of additional functional groups
    • Abstract: Publication date: 15 September 2018Source: Catalysis Today, Volume 314Author(s): Isao Ogino, Yukei Suzuki, Shin R. MukaiAnalysis of literature data on acid-catalyzed esterification reaction of levulinic acid (LA) with ethanol (EtOH) has suggested that some sulfonated carbon catalysts exhibit higher active-site performance than other solid acid catalysts such as macroreticular resins bearing sulfonic acid groups, zeolites, mesoporous silica functionalized with alkyl- and arene-sulfonic acid groups. To elucidate factors that enable the higher performance of sulfonated carbon catalysts, a series of sulfonated carbon catalysts was synthesized by sulfonating various carbon materials whose concentrations of surface oxygen-containing functional groups, porous structure, and swelling ability differ significantly. The catalysts were tested not only in the liquid-phase esterification reaction of LA with EtOH but also in the reaction of acetic acid (AcA) with EtOH because the latter reaction serves as a test reaction to probe the performance of –SO3H sites with minimal influence by mass transfer limitation and to provide an insight into a role of γ-keto group of LA in catalysis. The results show that all catalysts exhibit nearly the same turnover frequency per –SO3H site in the esterification reaction of AcA with EtOH despite widely different structural properties. In contrast, the data indicate that neighboring functional groups such as –COOH and –OH facilitate the reaction of LA with EtOH presumably through hydrogen-bonding interaction between these surface functional groups and γ-keto group of LA. These results suggest a general design strategy to improve the performance of solid acid catalysts further by precisely tuning the distance between –SO3H sites and neighboring functional groups.Graphical abstractGraphical abstract for this article
       
  • Sulfonated biochar as acid catalyst for sugar hydrolysis and dehydration
    • Abstract: Publication date: 15 September 2018Source: Catalysis Today, Volume 314Author(s): Xinni Xiong, Iris K.M. Yu, Season S. Chen, Daniel C.W. Tsang, Leichang Cao, Hocheol Song, Eilhann E. Kwon, Yong Sik Ok, Shicheng Zhang, Chi Sun PoonThis study investigated the use of 30 w/v% H2SO4 sulfonated wood waste-derived biochar as catalysts for production of value-added chemicals from carbohydrates in water as an environmentally benign solvent. Physicochemical characteristics of the sulfonated biochar were revealed by Fourier transform infrared spectroscopy (FTIR), acid-base neutralization titration, gas adsorption analysis, thermogravimetric analysis (TGA), and scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX). Using the sulfonated biochar as catalysts, hydrolysis of maltose at 140–160 °C resulted in the maximum glucose yield of 85.4% and selectivity of 88.2%, whereas dehydration of fructose at 160–180 °C produced the maximum HMF yield of 42.3% and selectivity of 60.4%. A higher range of reaction temperature was required for fructose dehydration due to the higher energy barrier compared to maltose hydrolysis. While increasing the temperature accelerated the catalytic reactions, the maximum product selectivity remained unchanged in the sulfonated biochar-catalyzed systems. The products were stable despite the increase in reaction time, because rehydration and adsorption of products was found to be minor although polymerization of intermediates led to unavoidable carbon loss. This study highlights the efficacy of engineered biochars in biorefinery as an emerging application.Graphical abstractGraphical abstract for this article
       
  • Three-dimensional red phosphorus: A promising photocatalyst with excellent
           adsorption and reduction performance
    • Abstract: Publication date: 15 September 2018Source: Catalysis Today, Volume 314Author(s): Lulu Qi, Kaiyue Dong, Tian Zeng, Jingyi Liu, Jun Fan, Xiaoyun Hu, Wanli Jia, Enzhou LiuRed phosphorus with three-dimensional nanostructure (3D-RP) was prepared by a hydrothermal method using commercial micron-sized RP as precursor. The investigation indicates that 3D-RP can harvest most of the visible light (Eg = 1.79 eV) and the BET surface area can reach 54.3 m2/g. It is interesting that 3D-RP exhibits quick adsorption property for methylene blue (MB) during the static adsorption experiment. Besides, Au and Cu ions can be adsorbed and reduced to their metallic states over the surface of 3D-RP without adding any reducing agent. Au and Cu species can greatly improve the photocurrent intensity and the photocatalytic hydrogen production efficiency of 3D-RP. This work is the primary investigation on the element phosphorus photocatalyst, further work should be conducted to explore more interesting properties about nano-sized RP.Graphical abstractGraphical abstract for this article
       
  • Preparation of perovskites PbBiO2I/PbO exhibiting visible-light
           photocatalytic activity
    • Abstract: Publication date: 15 September 2018Source: Catalysis Today, Volume 314Author(s): Fu-Yu Liu, Jia-Hao Lin, Yong-Ming Dai, Li-Wen Chen, Shiuh-Tsuen Huang, Tsung-Wen Yeh, Jia-Lin Chang, Chiing-Chang ChenThe first synthetic study on PbBiO2I/PbO nanocomposite preparation using a controlled hydrothermal method is reported. The morphologies and composition of the samples are controlled by adjusting some parameters, including reaction pH, Pb/Bi molar ratio, and temperature. All the samples are characterized by XRD, TEM, XPS, SEM-EDS, PL, BET, EPR, and UV–vis-DRS. The photodegradation activities are evaluated against the de-colorization of crystal violet (CV) and 2-hydroxybenzoic acid (2-HBA) in aqueous solution under visible light illumination. In particular, the catalytic performance illustrates the best reaction rate constant 1.159 × 10−1 h−1 once PbBiO2I/PbO is used as the photocatalyst for the degradation of CV; which is 3 and 20 times higher than the reaction rate constants of PbBiO2I and PbO being the photocatalysts, respectively. This study reveals that PbBiO2I/PbO can be used for repressing the recombination of photo-generated electron-hole pairs and contribute to the enhanced photocatalytic activity of semiconductors in the visible-light-driven catalysis. The possible photocatalytic degradation mechanism is studied by using different active species through EPR and adding suitable scavengers. When being irradiated, two major active species, O2− and 1O2, and a minor active species, h+, can be produced for the CV degradation.Graphical abstractGraphical abstract for this article(a) FE-TEM images, (b) SAD, (c) HR-TEM, (d) mapping, and (e) EDS of PbBiO2I/PbO (P1BI-250-10-12) sample by the hydrothermal autoclave method.
       
  • Simultaneous generation of oxygen vacancies on ultrathin BiOBr nanosheets
           during visible-light-driven CO2 photoreduction evoked superior activity
           and long-term stability
    • Abstract: Publication date: 15 September 2018Source: Catalysis Today, Volume 314Author(s): Xin Ying Kong, Boon-Junn Ng, Kok Hong Tan, Xiaofang Chen, Huanting Wang, Abdul Rahman Mohamed, Siang-Piao ChaiUnder the tremendous pressure of imminent energy crisis and anthropogenic climate change, photocatalytic conversion of abandoned CO2 into energy-rich hydrocarbon fuels is highly desirable. However, this solar-to-fuel conversion is unavoidably suppressed by the fast recombination of electron-hole pairs and lack of stability of photocatalysts. To overcome this, we have developed ultrathin BiOBr nanosheets (BOB-NS) with primarily exposed {001} facets. The {001} facets of BOB-NS are comprised of high density O atoms, which are linked to the neighbouring Bi atoms via weak BiO bonds with long bond length and low bond energy. After visible-light-driven CO2 photoreduction over BOB-NS, we found that the BiO bonds were broken and oxygen vacancy (OV) defects formed on the sample surface. The presence of these OVs was proven to be beneficial for photoactivities as photoinduced electrons were effectively trapped at the OV sites and recombination of charge carriers were inhibited. Generally, the free O atoms from dissociation of CO2 would reoxidize the sample surface, thereby deteriorating the performance of photocatalysts. In contrast, we demonstrated in this study that the OV sites on BOB-NS could be simultaneously regenerated and refreshed as the reactions proceeded, leading to a sustainable activity and long-term stability for CO2 photoreduction.Graphical abstractGraphical abstract for this article
       
  • Novel Ag@AgCl@AgBr heterostructured nanotubes as high-performance
           visible-light photocatalysts for decomposition of dyes
    • Abstract: Publication date: 15 September 2018Source: Catalysis Today, Volume 314Author(s): Jun-Qi Xiao, Kuen-Song Lin, Yan YuRecently, AgX (X = Cl, Br, I) materials have been demonstrated as novel and efficient visible-light photocatalysts for the decomposition of various organic compounds and dyes. Herein, heterostructured Ag@AgCl@AgBr nanotubes were prepared by an anion-exchange reaction between Ag@AgCl nanotubes and Br− anions, and their photocatalytic activities towards the decomposition of organic pollutants were studied. The as-synthesized photocatalysts were characterized using X-ray diffraction (XRD), field-emission scanning electron microscopy (FE–SEM), high-resolution transmission electron microscopy combined with energy-dispersive X-ray spectroscopy (HR–TEM/EDS), X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) spectroscopy. The structure characterization studies confirmed that the photocatalysts had nanotubular morphology. Compared to polyhedral Ag@AgBr nanoparticles, the incorporation of Br− ions into the Ag@AgCl framework remarkably enhanced the photocatalytic activities. The as-prepared Ag@AgCl@AgBr nanotubes can also be reused due to their high stability. Under visible light irradiation,>98.5% of Rhodamine B (RhB) and 90.3% of Red Acid I (RAI) were decomposed within 45 min using the catalyst AB–2 (Cl−/Br- = 1:1). The catalyst AB–2 displayed higher photocatalytic activity due to its enhanced surface area and photoelectron transfer, attributed to its novel heterostructured configuration.Graphical abstractGraphical abstract for this article
       
  • In situ growing of Bi/Bi2O2CO3 on Bi2WO6 nanosheets for improved
           photocatalytic performance
    • Abstract: Publication date: 15 September 2018Source: Catalysis Today, Volume 314Author(s): Jie Liu, Ying Li, Ziwei Li, Jun Ke, Huining Xiao, Yang HouA novel ternary hybrid photocatalyst Bi/Bi2O2CO3/Bi2WO6 is fabricated by a facial one-pot hydrothermal method, through the in situ growth of Bi and Bi2O2CO3 on the surface of 2D Bi2WO6 nanosheets. The Bi/Bi2O2CO3/Bi2WO6 hybrid exhibits the significantly enhanced photocatalytic activity, evaluated by the photo-oxidation of methylene blue (MB) and chlorobenzene. The improved photocatalytic activity is attributed to the surface plasmon resonance (SPR) effect of metallic Bi and the formation of the heterojunction among the three components in Bi/Bi2O2CO3/Bi2WO6 hybrid. The SPR effect of Bi nanoparticles leads to the great light response ability to the entire UV–vis light. And the SPR effect of metallic Bi, combined with Bi2O2CO3/Bi2WO6 heterojunction, also facilitates the rapid separation and transferring of the photogenerated charge carries, as well as the efficient suppression of the recombination of photogenerated electrons and holes.Graphical abstractGraphical abstract for this article
       
  • Preface: Advancement in Energy and Environmental Catalysis in Asia Pacific
           (Selected contributions from APCChE 2017)
    • Abstract: Publication date: 15 September 2018Source: Catalysis Today, Volume 314Author(s): Alex C.K. Yip, Wey Yang Teoh, Hou Yang
       
  • Hydrodeoxygenation of acetophenone over a sulfonated carbon-supported
           ruthenium catalyst
    • Abstract: Publication date: 15 September 2018Source: Catalysis Today, Volume 314Author(s): Jingtuo Wang, Ying Zhang, Meng Zhang, Zhiqiang Wang, Minghui ZhangA sulfonated active carbon supported Ru catalyst was prepared and tested in hydrodeoxygenation of acetophenone. The catalysts were characterized by XRD, TEM, N2 adsorption and NH3-TPD. The influences of reaction parameters on the conversion and selectivity were studied. An acetophenone conversion of 100% with total 90% selectivity of deoxygenated products was achieved at 150 °C over this catalyst, which was more active than the active carbon (AC) or SiO2 supported Ru catalysts. The enhanced performance of sulfonated AC supported Ru was attributed to the stronger acid sites and the better dispersion of Ru species. Moreover, such a catalyst was stable under the current reaction conditions and can be reused several times without obvious loss of activity.Graphical abstractA sulfonated carbon supported Ru catalyst as the acid and hydrogenation bifunctional catalyst was prepared, which showed much higher activity than conventional carbon or SiO2 supported Ru catalysts in hydrodeoxygenation of acetophenone reaction.Graphical abstract for this article
       
  • Sand supported TiO2 photocatalyst in a tray photo-reactor for the removal
           of emerging contaminants in wastewater
    • Abstract: Publication date: 1 September 2018Source: Catalysis Today, Volume 313Author(s): Yasmine K. Abdel-Maksoud, Emad Imam, Adham R RamadanThere have been rising concerns about micro-pollutants that are not efficiently removed by conventional wastewater treatment plants. TiO2 photocatalysis is one of the most promising methods for their removal. One of the major challenges to the widespread application of TiO2 photocatalytic treatment is the use of fine TiO2 particles in suspension.A tray photocatalytic reactor based on using supported TiO2 as a photocatalyst was designed and constructed. The reactor maintains a thin water film over TiO2 supported on sand grains. Reactor performance for the degradation of phenol as a model compound was evaluated using 3 different approaches: (1) direct immobilization using the sol gel technique, (2) coating with TiO2/cement grout; and (3) binding with TiO2-epoxy coating.The recirculating tray configuration achieved photocatalyst activation, turbulent flow, avoiding treatment dead zones, and continuous water oxygenation. The reactor performance using the epoxy TiO2 sand composite was satisfactory in terms of degradation efficiency. The water turbidity remained unchanged indicating photocatalyst resistance to abrasion. Successful operation of the tray photo-reactor in the continuous mode was also achieved. The tray reactor is suitable for scale-up and commercialization due to five distinctive features which are: modular design; integrated storage; ease of continuous mode operation; absence of need for UV transmitting components; robustness and low cost of the epoxy-TiO2-sand composite.Graphical abstractGraphical abstract for this article
       
  • Associating low crystallinity with peroxo groups for enhanced visible
           light active photocatalysts
    • Abstract: Publication date: 1 September 2018Source: Catalysis Today, Volume 313Author(s): Tamás Gyulavári, Gábor Veréb, Zsolt Pap, András Dombi, Klára HernádiIn the present study hydrogen peroxide was applied during the synthesis of titanium dioxide (TiO2) photocatalysts to anchor peroxo groups onto the surface to enhance visible light excitability. The effect of changes in the pH value and crystallization temperature was investigated. As-prepared peroxo-titania were characterized by X-ray diffraction (XRD), diffuse reflectance spectroscopy (DRS), infrared spectroscopy (IR), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS). The photocatalytic activity was investigated using phenol as model contaminant under visible light irradiation. IR and XPS measurements confirmed the presence of peroxo groups in the samples, moreover Raman and XPS measurements showed the formation of amorphous sodium titanate. Photocatalytic activity measurements pointed out, that most efficient as-prepared photocatalyst exceeded the photocatalytic performance of all reference materials. The cause of the enhanced photocatalytic activity was attributed to the enhanced visible light excitability and considerable amount of peroxo groups, which were not stable after the reusability experiments of the photocatalysts, suffering a redox reaction with the relatively high amount of Ti3+, resulting Ti4+ and surface OH groups. Therefore, the loss of peroxo groups and concomitantly photocatalytic activity was observed.Graphical abstractGraphical abstract for this article
       
  • Kinetic analysis supporting multielectron reduction of oxygen in bismuth
           tungstate-photocatalyzed oxidation of organic compounds
    • Abstract: Publication date: 1 September 2018Source: Catalysis Today, Volume 313Author(s): Haruna Hori, Mai Takashima, Mai Takase, Bunsho OhtaniLight-intensity dependence of the rate of carbon-dioxide liberation in the photocatalytic decomposition of acetic acid by bismuth tungstate particles suspended in an aqueous solution under aerobic conditions was measured by monochromatic photoirradiation using a monochromator (lower intensity
       
  • Assessing photocatalytic activity using methylene blue without dye
           sensitisation
    • Abstract: Publication date: 1 September 2018Source: Catalysis Today, Volume 313Author(s): Soo-Keun Lee, Andrew Mills, Nathan WellsThe anaerobic photocatalysed reduction of methylene blue, MB, by glycerol to leuco methylene blue, LMB, is studied using UV-absorbing, P25 TiO2, and visible-absorbing, CdS, semiconductor powder particles as the photosensitizer. In both cases, the photo-reductive bleaching of the dye to LMB, is very rapid, typically
       
  • Influence of the supporting electrolyte on the removal of ionic liquids by
           electrolysis with diamond anodes
    • Abstract: Publication date: 1 September 2018Source: Catalysis Today, Volume 313Author(s): Ismael F. Mena, Salvador Cotillas, Elena Díaz, Cristina Sáez, Ángel F. Mohedano, Manuel A. RodrigoIn this work, it is studied the electrolysis with diamond anodes of three different ionic liquids (ILs): 1-butyl-3-methylimidazolium chloride (BmimCl), 1-hexyl-3-methylimidazolium chloride (HmimCl) and 1-decyl-3-methylimidazolium chloride (DmimCl), which differ only in the length of the aliphatic carbon chain attached to the imidazolium group. In addition, the effect of the presence of sulfate in the electrolyte is also evaluated. Results confirmed that this type of ILs can be completely transformed into carbon dioxide, nitrates, ammonium (the imidazolium cation) and perchlorate and chloramines (the chloride anion) during the electrolysis of the synthetic waste containing sulfate. The electrolysis of wastes without sulfate anions leads to a much less efficient process, with the same final products in the case of the BminCl and HminCl ILs and with the formation of a polymer as the main final product in the case of the DmimCl. These results are of a paramount significance from a mechanistic point of view since, because of the high conductivity of the ILs, there is not a necessity of salt addition and they inform about the pure removal of these compounds by electrolysis with BDD, pointing out the important influence of peroxodisulfate on the electrolyses with diamond of organic wastes.Graphical abstractGraphical abstract for this article
       
  • Optimization of electro-Fenton process for effective degradation of
           organochlorine pesticide lindane
    • Abstract: Publication date: 1 September 2018Source: Catalysis Today, Volume 313Author(s): Carmen M. Dominguez, Nihal Oturan, Arturo Romero, Aurora Santos, Mehmet A. OturanLindane is an organochlorine pesticide broadly used in the last decades. It is persistent and recalcitrant in aquatic environments and difficult to biodegrade. This study is focused on the complete degradation of lindane by an electrochemical advanced oxidation process, the electro-Fenton (EF) process, using a BDD anode and carbon felt (CF) cathode. The influence of the main operating parameters, i.e., applied current intensity (50–1000 mA), catalyst concentration (0.0–0.5 mM) and initial pollutant concentration (5.0–10.0 mg L−1) has been investigated and optimized. The applied current plays a determinant role both in oxidation of lindane and mineralization of its aqueous solution. Taking into account the mineralization current efficiency (MCE) and the specific energy consumption (EC), the applied current of 400 mA was found to be the most convenient value. Catalyst (Fe2+) concentration as low as 0.05 mM, promotes efficiently H2O2 decomposition into hydroxyl radicals improving the efficiency of the process and minimizing the involvement of parasitic reactions. The initial pollutant concentration does not affect the performance of the process. At the optimum operating conditions, the complete degradation of 10 mg L−1 lindane solution and 80% of TOC removal were achieved at 15 min and 4 h, respectively.Graphical abstractGraphical abstract for this article
       
  • Degradation of organic compounds in wastewater matrix by electrochemically
           generated reactive chlorine species: Kinetics and selectivity
    • Abstract: Publication date: 1 September 2018Source: Catalysis Today, Volume 313Author(s): Chong Min Chung, Seok Won Hong, Kangwoo Cho, Michael R. HoffmannIn this study, we examined the kinetics and selectivity of chemical oxygen demand (COD) degradation by electrochemically generated reactive oxygen species (RCS) in variable wastewater matrix. According to measurements on reactive oxidants and linear sweep voltammetry, oxidation of organics either via reactive oxygen species or direct electron transfer played a minor role for the active IrO2 anode. The RCS (mostly free chlorine in bulk solution) exclusively mediated an indirect oxidation with mean current efficiency from 25 to 40%. In batch galvanostatic experiments for single polymeric compounds, the rate of COD reduction showed marginal variations in spite of the large difference in reactivity with the RCS. Eight different wastewater samples were prepared from greywater and urine for potentiostatic experiments. The kinetics of COD degradation in municipal wastewater was observed to more sluggish than in the urinary samples with initial elevations in [COD]. Fractionation of COD into proteins, carbohydrates, and carboxylates could explain the shift in kinetics, in terms of the reactivity with RCS and the ratio of COD to theoretical oxygen demand (ThOD) for each components. The anaerobic biodegradation of the organic matrix greatly improved the subsequent reactivity with RCS, which rationalizes a combination of electrochemical processes with biological pretreatment.Graphical abstractGraphical abstract for this article
       
  • Degradation of herbicide S-metolachlor by electrochemical AOPs using a
           boron-doped diamond anode
    • Abstract: Publication date: 1 September 2018Source: Catalysis Today, Volume 313Author(s): Diego Roberto Vieira Guelfi, Fábio Gozzi, Amílcar Machulek Jr., Ignasi Sirés, Enric Brillas, Silvio C. de OliveiraThe degradation and mineralization ability of electrochemical processes like electro-oxidation with electrogenerated H2O2 (EO-H2O2), electro-Fenton (EF) and UVA-assisted photoelectro-Fenton (PEF) has been comparatively studied for solutions of the herbicide S-metolachlor. Solutions of 100 mL have been treated using an undivided cell equipped with an air-diffusion cathode and a boron-doped diamond (BDD) anode. The effect of pH, current density, and Fe2+ and S-metolachlor concentrations has been thoroughly studied. The total organic carbon removal profiles have demonstrated the feasibility of almost overall mineralization by EF and PEF after 9 h at 300 mA. The herbicide decays in both treatments informed about the complexation of Fe(III) ions formed from Fenton’s reaction, which decelerated S-metolachlor removal. However, the high oxidation power of BDD anode allowed the gradual mineralization of such complexes. The identification of chlorinated and non-chlorinated degradation byproducts by GC–MS has allowed the proposal of main degradation routes.Graphical abstractGraphical abstract for this article
       
  • Sulfamethoxazole mineralization by solar photo electro-Fenton process in a
           pilot plant
    • Abstract: Publication date: 1 September 2018Source: Catalysis Today, Volume 313Author(s): J.C. Murillo-Sierra, E. Ruiz-Ruiz, L. Hinojosa-Reyes, J.L. Guzmán-Mar, F. Machuca-Martínez, A. Hernández-RamírezThe sulfamethoxazole (SMX) mineralization through the solar photo electro-Fenton (SPEF) process in a pilot plant containing 20 L of 50 mg L−1 SMX solution was investigated. The process was carried out at pH 3 under different operational conditions varying temperature, volumetric flow and applied current density. Box-Behnken experimental design and response surface methodology (RSM) were used to optimize the experimental variables of the SPEF process. Under the optimal conditions, the SPEF was compared with electro-Fenton (EF) and anodic oxidation (AO- H2O2) processes. Under optimum design variables of 47 mA cm−2, 45 °C and 571 L h−1, SPEF was more efficient yielding 90% of TOC removal after 360 min of reaction with a maximum of 83% of mineralization current efficiency (MCE). The main by-products detected on the final solution treated by SPEF were oxalic, maleic, oxamic and fumaric acids, while NH4+ and NO3− were the main inorganic nitrogen ions released during the process.Graphical abstractGraphical abstract for this article
       
  • Impact of TiO2/UVA photocatalysis on THM formation potential
    • Abstract: Publication date: 1 September 2018Source: Catalysis Today, Volume 313Author(s): E.M. Rodríguez, M.V. Gordillo, A. Rey, F.J. BeltránIn drinking water treatment plants, reduction of trihalomethane formation potential (THMFP) can be reached through precursor removal prior chlorine disinfection. In this work, the impact of TiO2/UVA photocatalytic process on THMFP has been studied using different phenolics (phenol, resorcinol, catechol, hydroquinone and gallic acid) and citric acid as NOM surrogates. A solution of each surrogate was photocatalytically treated at pH 7 applying different UVA doses and then chlorinated. Resorcinol oxidation by TiO2/UVA and THMFP reduction go hand in hand, indicating that the intermediates hardly form THMs when chlorinated. For the rest of surrogates, intermediates with medium-high specific THMFP (maximum values 40–120 μg CHCl3 (mg DOC)−1 for phenols; and ∼1000 μg CHCl3 (mg DOC)−1 for citric acid) are initially formed and disappear at higher UVA doses. TiO2/UVA treatment of water matrices with high and low specific UV absorption at 254 nm (SUVA254) (Sigma-Aldrich humic acid, pH 7; and water from Villar del Rey reservoir; Badajoz-Spain), was also investigated. For surface water UVA doses higher than 5 kWh m−3 were needed to achieve a THMFP below 100 μg THM L−1. During water treatment, an initial negative impact of AOPs in general and TiO2/UVA in particular on THMFP is expected.Graphical abstractGraphical abstract for this article
       
  • Type I vs Type II photodegradation of pollutants
    • Abstract: Publication date: 1 September 2018Source: Catalysis Today, Volume 313Author(s): R. Martinez-Haya, M.A. Miranda, M.L. MarinRose Bengal (RB) is a widely used photocatalyst due to its high quantum yield of singlet oxygen (1O2) formation. Hence, when RB has been employed for wastewater remediation, the observed photodegradation has been attributed to reaction between the pollutants and the 1O2 formed (Type II mechanism). However, RB could also react, in principle, via electron transfer (Type I mechanism). Herein, competition between Type I vs Type II oxidation has been investigated for RB in the photodegradation of emerging pollutants such as diclofenac (DCF) and acetaminophen (ACP). In parallel, the photocatalyst perinaphthenone (PN) has also been evaluated for comparison. The degree of removal achieved for both pollutants in aerated/deaerated aqueous solutions irrespective of the employed photocatalyst does not support the involvement of 1O2 as the main species responsible for removal of the pollutants. Photophysical experiments showed that the triplet excited states of RB and PN are efficiently quenched by both DCF and ACP. Moreover, 1O2 emission was also quenched by DCF and ACP. Thus the contribution of Type I versus Type II in the photodegradation has been evaluated from the experimentally determined rate constants. Nevertheless, at the upper limit for the typical concentration of emerging pollutants (10−5 M) photodegradation proceeds mainly via Type I mechanism.Graphical abstractGraphical abstract for this article
       
  • Rapid oxidation of paracetamol by Cobalt(II) catalyzed sulfite at alkaline
           pH
    • Abstract: Publication date: 1 September 2018Source: Catalysis Today, Volume 313Author(s): Yanan Yuan, Dan Zhao, Jinjun Li, Feng Wu, Marcello Brigante, Gilles MailhotIn this study we have investigated the efficiency Cobalt (II) (Co(II)) for the activation of sulfite ions following the oxidation of paracetamol used as model contaminants. Physico-chemical parameters that can impact the paracetamol degradation (pH, initial paracetamol concentration, Co(II)/S(IV) molar ratio, oxygen concentration) and contribution of various radicals were investigated in order to elucidate the chemical mechanism. Main results show that the pH is a key factor controlling the efficiency in the system Co(II)/Sulfite. Higher efficiency is observed for pH between 9.0 and 10.0. Increasing S(IV) concentrations, until 1 mM, slightly promoted the degradation of paracetamol. In fact, an excess of sulfite ions inhibits the reaction through the scavenging of SO4− and SO5−. Moreover, degradation efficiency drastically decreases from ∼ 85% to less than 5% in absence of oxygen. SO4− was confirmed to be the main oxidant responsible for the paracetamol degradation. For the first time we determined the second order rate constant between SO4− and paracetamol (1.33 ± 0.79 × 109 M−1 s−1 (at pH 5) and 6.14 ± 0.99 × 108 M−1 s−1 (at pH 11.0)). Moreover, radical-scavenging experiments also suggest the possible implication of SO5−. Hence, this work provides a precise understanding of the overall mechanism and a new promising strategy by using sulfite and transition metal such as Co(II) to promote organic compounds degradation in water under neutral and alkaline pH conditions.Graphical abstractGraphical abstract for this article
       
  • Solar photocatalytic degradation of propyl paraben in Al-doped
           TiO2 suspensions
    • Abstract: Publication date: 1 September 2018Source: Catalysis Today, Volume 313Author(s): Sophia Kotzamanidi, Zacharias Frontistis, Vassilios Binas, George Kiriakidis, Dionissios MantzavinosThe photocatalytic degradation of propyl paraben (PP) over Al-doped TiO2 suspensions under simulated solar radiation was investigated. The catalysts were prepared by a co-precipitation method with the dopant content varying from 0.04 to 2 wt%. The catalyst with 0.04 wt% dopant was more effective than the rest, presumably due to a more efficient separation of the photogenerated charges associated with a greater crystallite size. Subsequent experiments with this catalyst showed that the rate of PP degradation (i) generally increased with increasing catalyst concentration in the range 125–1000 mg/L, and decreasing PP concentration (in the range 210–1687 μg/L), and (ii) was impeded at alkaline conditions (pH range 3–9). Moreover, degradation in pure water was always faster than in actual (i.e. bottled water, treated wastewater, surface water) or synthetic (i.e. pure water spiked with humic acid, t-butanol, chloride and bicarbonate ions) water matrices, pinpointing the competitive behavior of non-target water constituents. Conversely, the addition of persulfate had a beneficial effect on the rate of degradation since it acted both as electron acceptor and a source of extra sulfate radicals.Graphical abstractGraphical abstract for this article
       
  • Fe-Ti alloy layer plasma deposition – Monitoring of plasma parameters
           and properties of deposited alloys, anodization and photoelectrochemical
           characterization
    • Abstract: Publication date: 1 September 2018Source: Catalysis Today, Volume 313Author(s): J. Olejníček, M. Zlámal, Z. Hubička, R. Perekrestov, P. Kšírová, M. Čada, Š. Kment, J. KrýsaMetallic Fe-Ti alloy thin films were deposited by high-power impulse magnetron sputtering (HiPIMS) on a glass substrate with an FTO electrode. Two-component alloys were prepared by sputtering of a single target, which was composed from two sectors made from different elements: iron disc and titanium ring. Chemical composition of alloy thin films was controlled by the width of titanium ring that partially covered iron target. These alloy thin films were anodized in fluorine-containing electrolyte with the aim to create mixed oxide nanostructures. Anodized layers were amorphous and transparent. After calcination, the layers consisted of crystalline Fe2O3 although TiO2 was still amorphous. Photoelectrochemical characterization show that increasing amount of titanium in the alloy results in the fabrication of Fe2O3/TiO2 nanostructures with higher photocurrent compared to those prepared from pure iron by the same anodization technique.Graphical abstractGraphical abstract for this article
       
  • Removal of an X-Ray contrast chemical from tertiary treated wastewater:
           Investigation of persulfate-mediated photochemical treatment systems
    • Abstract: Publication date: 1 September 2018Source: Catalysis Today, Volume 313Author(s): Idil Arslan-Alaton, Olga Kolba, Tugba Olmez-HanciThe degradation of 2.6 μM (2 mg/L) iopamidol (IOPA), a commercially important nonionic, iodinated X-ray contrast chemical and model micropollutant, by UV-A and UV-C photo-assisted persulfate (PS) oxidation in real, tertiary treated municipal wastewater (Organic carbon = 12.4 mg/L; Alkalinity = 130 mg CaCO3/L; pH = 7.0) was investigated. Preliminary baseline experiments conducted in pure (distilled) water indicated that IOPA could be rapidly and completely removed even by UV-C treatment alone. In the presence of UV-A light, 100% IOPA removal could still be achieved in pure water by PS/UV-A treatment which was studied at varying conditions (0.10–1.00 mM; pH3-11). However, in real wastewater, addition of at least 0.10 mM and 1.00 mM PS was required to achieve high (>90%) IOPA removals by the PS/UV-C and PS/UV-A treatment systems, respectively. PS consumption rates increased under UV-C radiation compared with UV-A radiation and in real wastewater compared to pure water. Organic carbon removals were appreciable for PS/UV-C (48%) and UV-C (40%) treatments in real wastewater. Toxicity assays carried out with the marine photobacteria Vibrio fischeri revealed that the toxicity response did not change significantly after photochemical treatment. According to the bioassay conducted with the freshwater microalga Pseudokirchneriella subcapitata, the toxicity increased after 155 min UV-C photolysis.Graphical abstractGraphical abstract for this article
       
  • Degradation of antibiotic sulfamethoxazole by biochar-activated
           persulfate: Factors affecting the activation and degradation processes
    • Abstract: Publication date: 1 September 2018Source: Catalysis Today, Volume 313Author(s): Liana Kemmou, Zacharias Frontistis, John Vakros, Ioannis D. Manariotis, Dionissios MantzavinosSpent malt rootlets were valorized to synthesize biochars for water treatment. In particular, the ability of biochar (BC) to activate sodium persulfate (SPS) for the oxidation of sulfamethoxazole (SMX), a representative antibiotic belonging to the family of emerging micro-contaminants, was tested. The biochar was fully characterized by nitrogen adsorption, FTIR spectroscopy, SEM, XRD, TGA and potentiometric mass titration (PMT); the biochar has a specific surface area of 100 m2/g, a point of zero charge value of 8.4 and its surface contains, amongst others, a considerable amount of hydroxyl groups probably in phenolic structure.The effect of various parameters such as SPS concentration (100–600 mg/L), SMX concentration (125–500 μg/L) and the water matrix (pure water, bottled water, treated domestic wastewater, alcohols as radical scavengers and humic acid) on degradation was investigated. The actual matrix effect on degradation was minor and so was the effect of radical scavengers. Based on the PMT curves, persulfate activation seems to occur on the biochar surface through interactions with the surface functional groups, generating radicals that are not released in the solution; this mechanism is promoted by the presence of humic acid.The biochar-induced SPS activation was also coupled with either 20 kHz ultrasound irradiation or simulated solar light. In either case, the combined activation was more efficient than the individual ones, leading to process synergy; the degree of synergy, based on pseudo-first order rate constants, was 23–35%.Graphical abstractGraphical abstract for this article
       
  • Fenton-based processes for the regeneration of catalytic adsorbents
    • Abstract: Publication date: 1 September 2018Source: Catalysis Today, Volume 313Author(s): A.M. Díez, M.A. Sanromán, M. PazosIn the present study, natural phyllosilicate clays, Illite and Montmorillonite, were stablished as efficient adsorbents for the removal of the ionic liquid 1-butyl, 2,3-dimethyl imidazolium chloride, achieving, respectively, 14 and 25 mg/g of adsorption. In addition, the regeneration of both adsorbents was hereby firstly performed by Fenton-based processes, using the catalytic action of the iron naturally present in clays. Two different reactor configurations, with regard to the ratio of adsorbent to liquid phase, were tested: fluidized and fixed bed reactors. The desorption equilibrium was the main limiting factor for the effective regeneration of the Illite clay by electro-Fenton process in the fluidized bed reactor. On the other hand, the fixed bed reactor, based on electrokinetic-Fenton phenomenon, proved to be suitable for the regeneration of the Montmorillonite clay and it would be an appropriate solution for the implementation of adsorbent regeneration by Fenton-based technology at large adsorbent/solution ratios. Both reactor configurations were suitable for the adsorbents regeneration, and 80% of ionic liquid degradation has been accomplished. Additionally, the adsorption capability of both clays was confirmed after the regeneration process, achieving almost the same initial uptake.Graphical abstractGraphical abstract for this article
       
  • A revised photocatalytic transformation mechanism for chlorinated VOCs:
           Experimental evidence from C2Cl4 in the gas phase
    • Abstract: Publication date: 1 September 2018Source: Catalysis Today, Volume 313Author(s): M. Minella, M. Baudino, C. MineroThe photodegradation of gaseous perchloroethylene (PCE) was investigated on titanium dioxide under UV light at 365 nm at the gas/solid interface in a CSTR photo-reactor (Continuous Stirred Tank Reactor). The rate and products are strongly affected by oxygen presence. Gaseous products of PCE degradation agree with literature. The production of active chlorine (sum of Cl2, HClO, ClO and ClO2) was investigated both in the presence of oxygen and in anoxic conditions. At low O2 concentration no gaseous active chlorine was determined, while a significant amount was measured in the presence of oxygen. By considering that in the absence of O2 the only possible form of active chlorine is Cl2, this highlights that Cl is not produced, and that chain reactions promoted by the chlorine radical do not occur on the TiO2 surface.The photocatalytic transformation of C2Cl4 was investigated at different concentrations. The rate follows a first order kinetic that is rationalized with a photocatalytic kinetic model in which the substrate is able to react simultaneously with both photogenerated holes and electrons. In anoxic conditions adsorbed halogenated organic compounds with molecular weights higher than that of PCE were produced and chloride ions accumulated at the surface. Reductive pathways have a key role in PCE degradation. The water vapor has a detrimental role on the PCE transformation rate due to the competition with PCE adsorption on reactive sites with 2:1 stoichiometry.The addition of chloride ions on TiO2 surface slows down the PCE degradation rate and the production of gaseous CCl4 but increments that of C2Cl6 in anoxic conditions. This is rationalized by a mechanism in which direct hole transfer to substrate occurs followed by chloride anion addition to the carbocation.Graphical abstractGraphical abstract for this article
       
  • Photoinduced transformation of glycerol in titania suspensions. (An EPR
           spin trapping study of radical intermediates)
    • Abstract: Publication date: 1 September 2018Source: Catalysis Today, Volume 313Author(s): Zuzana Barbieriková, Dana Dvoranová, Vlasta BrezováFormation of radical intermediates upon photocatalytic (UVA) glycerol transformation in aerated aqueous TiO2 (P25) suspensions was followed by EPR spin trapping technique. Character and concentration of the spin-adducts generated by the addition of the radical species to 5,5-dimethyl-1-pyrroline N-oxide (DMPO) spin trap are significantly affected by the UVA radiation dose and by the initial composition of the photocatalytic system. The DMPO spin-adducts of hydroxyalkyl radicals R1 and R2 detected in the aerated aqueous P25 suspensions containing glycerol are compatible with the H-abstraction processes attributed to the interaction of physisorbed glycerol molecules with the trapped holes or to the reaction of free hydroxyl radicals with glycerol in solution. Addition of fluoride at various concentrations has no effect on the character and concentration of DMPO spin-adducts observed upon in situ UVA photoexcitation of photocatalytic system P25/DMPO/glycerol under given experimental conditions (pH > 7).Graphical abstractGraphical abstract for this article
       
  • ZrO2 Based materials as photocatalysts for 2-propanol oxidation by using
           UV and solar light irradiation and tests for CO2 reduction
    • Abstract: Publication date: 1 September 2018Source: Catalysis Today, Volume 313Author(s): E. García-López, G. Marcì, F.R. Pomilla, M.C. Paganini, C. Gionco, E. Giamello, L. PalmisanoBare ZrO2, Ce doped ZrO2 and Er doped ZrO2 samples have been prepared by a hydrothermal process and have been used as photocatalysts for 2-propanol oxidation reaction in gas solid regime. Moreover, some preliminary tests have been carried out for CO2 reduction. The samples were physico-chemically characterized and both bare and doped ZrO2 based materials resulted active for oxidation and reduction reactions by using UV and solar irradiation. The reactivity results have been correlated with the compositional, structural and morphological features of the photocatalysts.Graphical abstractGraphical abstract for this article
       
  • Inactivation of a wild isolated Klebsiella pneumoniae by photo-chemical
           processes: UV-C, UV-C/H2O2 and UV-C/H2O2/Fe3+
    • Abstract: Publication date: 1 September 2018Source: Catalysis Today, Volume 313Author(s): Silvio Aguilar, Daniel Rosado, Javier Moreno-Andrés, Luis Cartuche, Darío Cruz, Asunción Acevedo-Merino, Enrique NebotShrimp (Litopenaeus vannamei) farming is an important economic activity in several countries. Pathogens in shrimp farms and its effluents pose a potential hazard for both humans and shrimps. Wild strains of bacteria were characterized in a shrimp farm, and Klebsiella pneumoniae was chosen as a good indicator due to its presence in the pond and the effluent and its resistance to antibiotics. Different photochemical processes (UV/H2O2, UV/H2O2/Fe3+) were tested for inactivation of wild isolated K. pneumoniae and compared to UV-C radiation. By kinetic modelling, a kmax equal to 0.43 s−1 was obtained for UV-C treatment. After optimizing the cited processes, ranging [H2O2]: 10–30 mg·l−1; an optimal [H2O2] of 10 mg·l−1 was found, increasing kmax on 13.63% compared to UV-C. This optimal concentration was tested for UV/H2O2/Fe3+ process; ranging [Fe3+]: 2–20 mg·l−1. The highest yield was obtained by a [H2O2]:[Fe3+] = 10:2, which leads to 4-Log reduction in 12.88 s of treatment. Moreover, resistance of K. pneumoniae was compared to Escherichia coli. The latter proved to be more sensitive despite its similar cellular structure. Results suggested that the photochemical processes could enhance disinfection efficiency, especially for photo-assisted Fenton-like process in most resistant bacteria.Graphical abstractGraphical abstract for this article
       
  • Solar light and the photo-Fenton process against antibiotic resistant
           bacteria in wastewater: A kinetic study with a Streptomycin-resistant
           strain
    • Abstract: Publication date: 1 September 2018Source: Catalysis Today, Volume 313Author(s): Stefanos Giannakis, Samuel Watts, Sami Rtimi, Cesar PulgarinIn this work, we assess the potential of solar light and the solar-assisted photo-Fenton process to inactivate antibiotic resistant bacteria (ARB) in wastewater (WW). A systematic investigation on ARB inactivation and regrowth kinetics after solar-based processes is intended, as well as the modification of their antibiotic resistance (AR). As such, a Streptomycin-resistant (SR) E. coli as a model ARB was subjected to solar exposure (with or without UVB light) at various irradiance levels, as well as the solar/H2O2 and the photo-Fenton process at neutral pH. We report the good fit of the SR E.coli to known kinetic models (>96% R2), and analytically present the necessary treatment timed for total inactivation and halting their post-treatment regrowth capability. For all treatment methods, the AR was found to decrease during treatment, prior to loss of cultivability (5–15% lower time for 4-log inactivation). UVB irradiation was determined as the key factor of loss of cultivability, AR and regrowth. Solar/H2O2 and photo-Fenton presented fast inactivation rates, ensured no regrowth of ARB, and indicated moderate effect on modifying the SR of E. coli, with similar inactivation times for both strains. The presence of Streptomycin in WW was found to act synergistically on the faster inactivation by all processes tested. Finally, ∼1 h of solar-based AOPs was found to ensure 4-log ARB inactivation and no regrowth, even in absence of the residual H2O2, indicating their suitability as proper WW disinfection processes.Graphical abstractGraphical abstract for this article
       
  • Effective solar processes in fresh-cut wastewater disinfection:
           Inactivation of pathogenic E. coli O157:H7 and Salmonella enteritidis
    • Abstract: Publication date: 1 September 2018Source: Catalysis Today, Volume 313Author(s): S. Nahim-Granados, J.A. Sánchez Pérez, M.I. Polo-LopezThe disinfection of synthetic fresh-cut wastewater (SFCWW) by several solar processes has been investigated as an alternative to the commonly used chlorination in this industry. To this end, a SFCWW recipe was developed based on real sample analysis from the fresh-cut industry and literature data. It is characterized mainly by the presence of organic matter in solution (25 mg/L DOC) and turbidity (100 NTU). The inactivation kinetics of human pathogenic bacteria (E. coli O157:H7 and Salmonella enteritidis) in SFCWW was assessed by solar photo-inactivation, H2O2/solar, iron/solar and solar photo-Fenton processes. Excellent inactivation performance was achieved in all cases demonstrating the capability of solar processes to disinfect water even at high levels of turbidity. The best bacterial inactivation rates were obtained with the H2O2/solar process (20 mg/L) in less than 60 min for both E. coli and S. enteriditis. Moreover, the influence of UVA irradiance (10–50 W/m2) on the inactivation of both pathogens by the H2O2/solar process at several H2O2 concentrations was investigated. These results showed a slightly different response for both pathogens against UVA irradiance and H2O2 concentration: photo-limitation for both types of bacteria; while only E. coli was limited by the H2O2 concentrations investigated in this work.Graphical abstractGraphical abstract for this article
       
  • Wild bacteria inactivation in WWTP secondary effluents by solar
           photo-fenton at neutral pH in raceway pond reactors
    • Abstract: Publication date: 1 September 2018Source: Catalysis Today, Volume 313Author(s): B. Esteban García, G. Rivas, S. Arzate, J.A. Sánchez PérezFor first time, the efficiency of raceway pond reactors for wastewater disinfection by solar photo-Fenton (50 mg H2O2/L and 20 mg Fe2+/L) at neutral pH has been shown in this study. Complete inactivation of wild total coliforms, E. coli and Enterococcus sp. in municipal wastewater treatment plant secondary effluents took place after 80 min. A comparison with a tubular reactor equipped with a compound parabolic collector (CPC) was carried out and disinfection times were the same for the CPC and RPR, the tubular one having a 5 cm tube diameter and the RPR was operated at 5 cm liquid depth. Both acute and chronic toxicity were evaluated before and after treatment in both reactors and their analysis showed no significant changes for the removal of either in the treated effluent in both reactors. Additionally, an economic assessment of the process in the RPR was also performed. Estimated total costs for a 400 m3/d scale solar photo-Fenton plant for disinfection (0.15 €/m3) were in the range of reclaimed water rates.Graphical abstractGraphical abstract for this article
       
  • Surface-grafted WO3/TiO2 photocatalysts: Enhanced visible-light activity
           towards indoor air purification
    • Abstract: Publication date: 1 September 2018Source: Catalysis Today, Volume 313Author(s): Narmina O. Balayeva, Manuel Fleisch, Detlef W. BahnemannRegardless of the fact that tungsten trioxide (WO3) is recognized as one of the most promising photocatalysts for potential activity under visible light illumination, it still suffers from intrinsic drawbacks such as photocorrision and an unsuitable band gap structure for the reduction of molecular oxygen. To overcome these limitations we herein report for the first time in-situ synthesized WO3 nanoparticles which were coupled with commercial TiO2 (P25) via a simple impregnation method. The surface of the composites were additionally grafted with varying contents (0.005–0.3 wt%) of Fe(III) nanoclusters with their synergistic performance being investigated. The photocatalytic activities of the obtained materials were evaluated by monitoring the decomposition of the model compounds nitric oxide (NO) and acetaldehyde under UV and visible light illumination. A significant improvement of visible light sensitivity was attained in comparison with bare WO3/TiO2. Additionally the synthesized photocatalysts have been characterized by using x-ray powder diffraction(XRD), transmission electron microscopy (TEM), electron paramagnetic resonance (EPR) spectroscopy, UV–vis diffuse reflectance spectroscopy and N2 adsorption (BET) for specific surface area determination. The EPR results confirmed a direct charge transfer from the VB of the composites to the surface grafted Fe(III) nanoclusters, which are promoting multi-electron reduction processes consequently resulting in the degradation of harmful gases.Graphical abstractProposed mechanism of the designed photocatalytic system.Graphical abstract for this article
       
  • Thermal sulfidation of α-Fe2O3 hematite to FeS2 pyrite thin electrodes:
           Correlation between surface morphology and photoelectrochemical
           functionality
    • Abstract: Publication date: 1 September 2018Source: Catalysis Today, Volume 313Author(s): Hana Kmentova, Stepan Kment, Zdenek Hubicka, Zdenek Remes, Jiri Olejnicek, Martin Cada, Josef Krysa, Radek ZborilThe pyrite iron disulfide thin films are regarded as suitable candidates for construction of low-cost photoelectrochemical (PEC) solar cells. Iron oxide hematite has attracted much attention as possibly convenient material for hydrogen production via PEC water splitting. We refer on preparation of pyrite thin films via thermal sulfidation of hematite films synthetized by a physical methodology of high power impulse magnetron sputtering (HiPIMS) and purely chemical approach of sol-gel. We studied for the first time the correlation between PEC functionality of hematite films and after their sulfidation into pyrite. The highest PEC activity of hematite films of 560 μA cm−2 at 700 mV vs. Ag/AgCl was achieved with the HiPIMS photoelectrodes. The photoefficiency dropped dramatically to 4 μA cm−2 at 600 mV vs. Ag/AgCl after the sulfidation. A significant increase of grains‘ size, residual unreacted hematite, surface defects were the main reasons for the poor photoactivity. The sol-gel produced hematite yielded photocurrent of 30 μA cm−2 and a slight increase to 40 μA cm−2 (recorded at 500 mV vs. Ag/AgCl) of the corresponding pyrite version. Both these electrodes showed also similar morphological characteristics. The structural, electronic and optical properties of the deposited films were determined using various methods e.g. Raman spectroscopy, SEM, and PDS.Graphical abstractGraphical abstract for this article
       
  • Solid state route for synthesis of YFeO3/g-C3N4 composites and its visible
           light activity for degradation of organic pollutants
    • Abstract: Publication date: 1 September 2018Source: Catalysis Today, Volume 313Author(s): Mohammed Ismael, Engy Elhaddad, Dereje H. Taffa, Michael WarkYFeO3/g-C3N4 composites with varying weight ratios were prepared following three different methods The optimum weight ratio and the method of preparation for enhanced visible photocatalytic activity towards the degradation of organic contaminants were identified. The successful formation of the composites was proven by XRD and IR measurements. XPS analysis shows that the inactive Y2O3 passive layer on the hexagonal YFeO3 (h-YFeO3) disappeared during the composite formation, resulting in a direct and intimate contact of h-YFeO3/g-C3N4 which is crucial for the photocatalytic activities. The loading of h-YFeO3 varied from 1 to 20% and the highest activity was achieved at 2.4%. At the optimum loading 80% degradation of methyl orange (MO) was obtained under 5 h visible light illumination. The composite photocatalyst shows also modest activity for the photodegrading of 4-chlorophenol (4-CP). Additionally the synthesized composites were characterized by high resolution transmission electron microscopy (HR-TEM), Fourier transform infrared spectroscopy (FT-IR) and diffuse reflection UV–vis spectroscopy (DR-UV–vis). In order to determine the relative band positions of the composite photocatalysts their flat band potentials were estimated from Mott-Schottky analysis. Improved charge separation in the composite is mainly responsible for the enhanced photoactivity and supported by photoluminescence experiments.Graphical abstractGraphical abstract for this article
       
  • Concurrent role of metal (Sn, Zn) and N species in enhancing the
           photocatalytic activity of TiO2 under solar light
    • Abstract: Publication date: 1 September 2018Source: Catalysis Today, Volume 313Author(s): Luca Rimoldi, Eleonora Pargoletti, Daniela Meroni, Ermelinda Falletta, Giuseppina Cerrato, Francesca Turco, Giuseppe CappellettiTiO2 modification by both non-metal and metal species is a popular strategy to promote the semiconductor visible light absorption and photocatalytic performance. In this work, tin and zinc are compared as metal promoters to enhance the photocatalytic activity of N-doped TiO2 under solar light. The synthesized samples were tested under both UV and simulated solar irradiation toward the photocatalytic degradation of tetracycline, an emerging water pollutant. All copromoted samples (N + Sn and N + Zn) revealed higher efficiency under solar light in the mineralization of the pollutant with respect to both the pristine and N-doped ones. The enhanced photocatalytic efficiency of these samples was traced back to the modifications introduced by the different guest species to the structural (X-ray Powder Diffraction, XRPD), morphological (High-Resolution Transmission Electron Microscopy, HR-TEM and Brunauer-Emmett-Teller analysis, BET), spectroscopic (X-ray Photoelectron Spectroscopy, XPS, Energy Dispersive X-ray Spectroscopy, EDX and Diffuse Reflectance Spectroscopy, DRS) and surface features (ζ-potential). In this regard, the increased surface area, the modifications of the phase composition and the enhanced visible light harvesting seem to play a pivotal role in affecting the photocatalytic performance. Mass spectrometry analyses allowed us to identify several reaction intermediates and propose different degradation mechanisms depending on the type of metal promoter.Graphical abstractGraphical abstract for this article
       
  • Influence of anodization mode on the morphology and photocatalytic
           activity of TiO2-NTs array large size electrodes
    • Abstract: Publication date: 1 September 2018Source: Catalysis Today, Volume 313Author(s): Esperanza Mena, María José Martín de Vidales, Sandra Mesones, Javier MarugánProperties of nanotubular titania structures (TiO2-NTs) have been widely evaluated in small electrodes at lab scale. A novel experimental approach to overcome the limitations for the anodization of large size electrodes is presented. Several potentiostatic and galvanostatic anodization procedures have been tested, and their impact on the morphological features of the TiO2-NTs analyzed. A clear relationship between the applied voltage and current density and the NTs length and diameter is confirmed. Photocatalytic activity of the TiO2-NTs structures was evaluated in the methanol oxidation reaction. From these results, it was obtained that kinetic constant for the photocatalytic oxidation of methanol is higher when the reaction is carried out with NTs of higher length/diameter aspect ratio. This is related to a higher TiO2 active surface area available to generate photo-induced electron-hole pairs and for the adsorption of the reactants. This work confirms the viability of formation of photocatalytically active large size TiO2-NTs electrodes when high voltage or current density is applied under controlled conditions. Availability of fluoride in the electrolyte can be ensured by the use of a novel concept of continuous flow anodization reactor allowing the renovation of the electrolyte to keep under control not only the composition but also the temperature of the solution.Graphical abstractGraphical abstract for this article
       
  • The influence of curing methods on the physico-chemical properties of
           printed mesoporous titania patterns reinforced by methylsilica binder
    • Abstract: Publication date: 1 September 2018Source: Catalysis Today, Volume 313Author(s): Petr Dzik, Michal Veselý, Martina Pachovská, Michael Neumann-Spallart, Vilma Buršíková, Tomáš HomolaWe report on the influence of post-printing curing on the physico-chemical properties of silica-bonded particulate titania photocatalytic layers. Ink consisting of commercial titania nanoparticles and a novel siloxane binder was patterned by inkjet printing. Printed layers were mineralized by three processes: thermal annealing by convection heating in an electric furnace, UV-curing with a high pressure mercury vapour lamp, and atmospheric plasma treatment in a coplanar dielectric barrier discharge. The influence of these processes on the extend of the binder mineralization and resulting physicochemical properties, charge generation and transport as well as photocatalytic activity was investigated. All curing methods proved to be capable to mineralize the binder but atmospheric plasma curing stands out as the fastest one enabling a direct implementation into roll-to-roll fabrication processes.Graphical abstractGraphical abstract for this article
       
  • Exploring the activity of chemical-activated carbons synthesized from
           peach stones as metal-free catalysts for wet peroxide oxidation
    • Abstract: Publication date: 1 September 2018Source: Catalysis Today, Volume 313Author(s): Maria Martin-Martinez, Silvia Álvarez-Torrellas, Juan García, Adrián M.T. Silva, Joaquim L. Faria, Helder T. GomesPeach stones were used as raw material for the synthesis of activated carbons with different properties. Firstly, peach stones were chemically activated using a 12 M H3PO4 solution and carbonized under flowing air (400 °C). The obtained activated carbon, named as PS, is characterized by a high surface development (SBET = 1262 m2 g−1) and acidic character (pHPZC = 4.2). A fraction of PS was further carbonized under N2 atmosphere at 800 °C to remove surface functionalities and to increase its basicity (PS-800). In addition, a Pt catalyst supported on PS (3% w/w Pt/PS) was synthesized by incipient wetness impregnation, resulting in a considerable hydrophilicity increasing. The synthesized materials were tested in the catalytic wet peroxide oxidation (CWPO) of highly concentrated solutions of 4-nitrophenol (4-NP, 5 g L−1) during 24 h experiments, conducted at relatively mild operating conditions (T = 50–110 °C, pH = 3, catalyst load = 2.5 g L−1 and [H2O2]0 = 17.8 g L−1, corresponding to the stoichiometric amount of H2O2 needed for the complete mineralization of 4-NP). It was observed that the increase of electron-donating functionalities in PS-800 promotes the generation of reactive HO radicals, being the activity towards CWPO twice higher than that obtained with the pristine PS. Besides, increasing operating temperature substantially enhances CWPO, finding a 80% of 4-NP removal at 110 °C. On the other hand, despite the sharp increment in H2O2 decomposition due to the presence of Pt particles in Pt/PS catalyst, this decomposition is inefficient in all cases, with a consequent poor pollutant removal. This can be attributed to the recombination of HO radicals into non-reactive species −scavenging effects, promoted by the hydrophilicity of the catalyst.Graphical abstractGraphical abstract for this article
       
  • ZnO and Pt-ZnO photocatalysts: Characterization and photocatalytic
           activity assessing by means of three substrates
    • Abstract: Publication date: 1 September 2018Source: Catalysis Today, Volume 313Author(s): C.A. Jaramillo-Páez, J.A. Navío, M.C. Hidalgo, M. MacíasZnO nanoparticles have been previously synthesized by a facile precipitation procedure by mixing aqueous solutions of Zn(II) acetate and dissolved Na2CO3 at pH ca. 7.0 without the addition of a template. The as-prepared ZnO material was anealed at 400 °C in air for 2 h. The Pt-ZnO catalysts (0.5 or 1.0 Pt wt.%) were obtained by photochemical deposition method on the surface of the prepared ZnO sample, using hexachloroplatinic acid (H2PtCl6). It has been shown that Zn2+ is lost from the photocatalyst to the medium and a replacement of the cationic vacancies of Zn2+ by Pt4+ cations occurs during the platinization process of the ZnO samples, regardless of whether the platinum metal photodeposition process. The as-prepared catalysts were characterized by XRD, BET, FE-SEM, TEM, XPS and diffuse reflectance spectroscopy (DRS). Three different probe molecules were used to evaluate the photocatalytic properties under UV-illumination: Methyl Orange and Rhodamine B were chosen as dye substrates and Phenol as a transparent substrate. High conversion values (ca. 100%) and a total organic carbon (TOC) removal of 90–96%, were obtained over these photocatalysts after 160 min of UV illumination. In general, it was observed that the presence of Pt on ZnO affects the lattice parameters and the crystallite size. Although ZnO can completely degrade RhB, MO and Phenol totally in ca. 60 min, the process is more efficient for Pt–ZnO photocatalysts.Graphical abstractGraphical abstract for this article
       
  • Sustainable Fe-BTC catalyst for efficient removal of mehylene blue by
           advanced fenton oxidation
    • Abstract: Publication date: 1 September 2018Source: Catalysis Today, Volume 313Author(s): Fernando Martínez, Pedro Leo, Gisela Orcajo, Manuel Díaz-García, Manuel Sanchez-Sanchez, Guillermo CallejaFe-based metal organic framework (MOF) materials −such as Fe-BTC and MIL-100(Fe)- have been explored as catalyst for advanced Fenton oxidation processes. Unlike the analogous commercial forms of these materials (Basolite F300 and KRICT F100, respectively), Fe-BTC and MIL-100(Fe) were prepared under environmentally and economically sustainable conditions (water as synthesis solvent and room temperature). These materials were tested for the degradation of methylene blue (MB) as model pollutant through Fenton oxidation. The Fe-BTC material prepared under sustainable conditions (SUST/Fe-BTC) evidenced the best catalytic performance, even at circumneutral pH, with a remarkable structural stability compared to the commercial Basolite F300 and MIL-100(Fe) samples. The influence of the reaction temperature, initial pH and hydrogen peroxide concentration was studied for the SUST/Fe-BTC material, achieving a MB removal close to 100% and a TOC reduction about 55% in 60 min for several reaction cycles using a low dosage of hydrogen peroxide, 40 °C and initial pH of 4.Graphical abstractGraphical abstract for this article
       
  • Preparation of Sn-doped semiconducting Fe2O3 (hematite) layers by aerosol
           pyrolysis
    • Abstract: Publication date: 1 September 2018Source: Catalysis Today, Volume 313Author(s): T. Kotrla, Š. Paušová, M. Zlámal, M. Neumann-Spallart, J. KrýsaFe2O3 films were deposited on transparent conductive substrates (fluorine doped tin oxide (FTO) on glass) by aerosol pyrolysis. The intrinsic nature of as-deposited films requires the addition of a suitable metal dopant. Sn proved to be well adapted to this task, as it increased photocurrents in junctions with an aqueous electrolyte by one order of magnitude as compared to undoped films. The maximum IPCE value (incident photon to current conversion efficiency) was 0.21 at 400 nm for a 120 nm thick film and a maximum photocurrent of 1630 μA/cm2 at 0.65 V vs. Ag/AgCl under simulated solar irradiation.Graphical abstractHematite on FTO, deposition temperature 650 °C, thickness 120 nm.Graphical abstract for this article
       
  • Antibiotics abatement in synthetic and real aqueous matrices by
           H2O2/natural magnetite
    • Abstract: Publication date: 1 September 2018Source: Catalysis Today, Volume 313Author(s): Macarena Munoz, Javier Conde, Zahara M. de Pedro, Jose A. CasasThe removal of micropollutants in wastewater treatment plants (WTTPs) is a challenging issue which requires the development of effective but also green and low-cost strategies. In this work, we explore the capability of naturally-occurring magnetite combined with H2O2 for the degradation of the highly persistent antibiotic sulfamethoxazole (SMX). A complete operating condition study has been performed to evaluate the effect of initial pH (3–7), temperature (15–50 °C), magnetite concentration (0.5–2 g L−1) and H2O2 dose (12.5–100 mg L−1), using an initial SMX amount of 5 mg L−1. Remarkably, complete removal of the target pollutant and the aromatic intermediates was achieved operating under ambient-like conditions (25 °C) and circumneutral pH (pH0 = 5) using the stoichiometric dose of H2O2 (25 mg L−1) and a catalyst load of 1 g L−1. The mineralization yield was above 50%, being the final oxidation products short-chain organic acids. The oxidation pathway of SMX was accordingly proposed. The stability of magnetite was confirmed upon three sequential runs, where a similar catalytic activity and negligible iron leaching (
       
  • Highly catalytic oxidative desulfurization and denitrogenation of diesel
           using anchored-silica-gel vanadium-substituted Dawson-type polyoxometalate
           
    • Abstract: Publication date: Available online 5 July 2018Source: Catalysis TodayAuthor(s): F. Banisharif, M.R. Dehghani, M.C. Capel-Sanchez, J.M. Campos-MartinThe aim of this article is to study the extractive-catalytic oxidative desulfurization (ECODS) of the model oil containing several model S-containing compounds as well as N-containing compound using a heterogeneous vanadium substituted Dawson-type polyoxometalate catalyst under atmospheric pressure and temperature lower than 100 °C. The catalyst was prepared by ion exchange with alkyl ammonium derivatives covalently anchored to silica gel. The potential of this methodology was illustrated by oxidation of 100% quinoline and 80% of total sulfur in model oil containing 500 ppmw sulfur and 70% of total sulfur in model oil 1500 ppmw in less than 30 min of reaction, in the absence of solvent. However, when acetonitrile was employed as an extractive solvent, the desulfurization was increased considerably. Under the reaction conditions, activated catalyst and acetonitrile, solvent to oil ratio 1:6, could remove approximately 100% of quinoline, 95% of sulfur from 500-ppmw model oil, 87% of sulfur from 1500-ppmw model oil in less than 30 min. The catalyst is very active in ECODS and can be reused fifth times from 500-ppmw model oil and third times from 1500-ppmw model oil without an important decrease in activity. The ECODS could remove 83% of total sulfur from 1235-ppmw-S real diesel.Graphical abstractGraphical abstract for this article
       
  • Production of 1,3-butadiene in one step catalytic dehydration of
           2,3-butanediol
    • Abstract: Publication date: Available online 5 July 2018Source: Catalysis TodayAuthor(s): N.T.T Nguyen, F. Matei-Rutkovska, M. Huchede, K. Jaillardon, G. Qingyi, C. Michel, J.M.M. MilletCatalysts able to selectively dehydrate 2,3-butanediol into butadiene have been designed. These catalysts, based on rare-earth orthophosphates showed that 58% selectivity to butadiene could be obtained at total conversion at only 300 °C, and were relatively stable. While the deactivation could be delayed by addition of water to the gas feeds, it could not be avoided and a regeneration was necessary. This regeneration was achieved by a simple heat treatment under air for a few hours at 450 °C. All results showed that Lewis acid sites corresponding to the rare earth cations are involved in the dehydration of 2,3-butanediol into butadiene. This dehydration occurs with the intermediate formation of 3-buten-2ol, probably over acid-base concerted sites and the subsequent dehydration of 3BDOL to butadiene over weak Brønsted acid sites. All types of sites appear present on the catalysts surface and distributed in a relatively optimal way.Graphical abstractGraphical abstract for this article
       
  • SCILLs as selective catalysts for the oxidation of aromatic alcohols
    • Abstract: Publication date: Available online 5 July 2018Source: Catalysis TodayAuthor(s): Iunia Podolean, Octavian D. Pavel, Haresh G. Manyar, S. F. Rebecca Taylor, Kathryn Ralphs, Peter Goodrich, Vasile I. Pârvulescu, Christopher HardacreThe cryptomelane form of manganese oxide, OMS-2, has been used a pure material as well as a 5 wt % Pt/OMS-2 catalyst for the oxidation of benzyl alcohol. In addition, these catalysts have been modified with ionic liquids via a thin layer of [Bmim][NTf2] or [Bmpyr][NTf2]. These catalysts were characterized using a series of techniques: NMR, XRD, DRIFT, Raman, BET, Dynamic Light Scattering, XPS, TEM, SEM. The Weisz–Prater criterion has also been considered to inform whether the reactions were under diffusional control. The presence of platinum on the OMS-2 surface results in the support transforming to form Mn3O4 during reaction. In contrast, in the presence of the ionic liquid, the catalysts exhibited an increased phase stability. Efficient oxidation of benzyl alcohol was observed with a conversion of 80% and 82% selectivity to aldehyde for 5 wt% Pt/OMS-2/[Bmim][NTf2] in air. As expected an increase of the oxygen pressure led to an increase in the conversion to the detriment of aldehyde selectivity. The catalytic tests also showed an important effect on the conversion and selectivity of benzyl alcohol as a function of the diluent gas comparing inert (N2, He, Ar) or (CO2) reactive gases. This effect was influenced by the nature of the ionic liquid present.Graphical abstractGraphical abstract for this article
       
  • Light-driven synthesis of sub-nanometric metallic Ru catalysts on
           TiO2
    • Abstract: Publication date: Available online 5 July 2018Source: Catalysis TodayAuthor(s): Joanna Wojciechowska, Elisa Gitzhofer, Jacek Grams, Agnieszka M. Ruppert, Nicolas KellerA one-step room temperature photo-assisted synthesis has been implemented in liquid phase and under solar light for preparing highly dispersed TiO2 supported metallic Ru catalysts, with no need of final thermal treatment, external hydrogen, or chemical reductant. Whether RuCl3 chloride or Ru(acac)3 acetylacetonate precursor salt was used, sub-nanometric metallic Ru nanoparticles were synthesized on TiO2 with a sharp size distribution, the high dispersion and the metallic nature of the nanoparticles being evidenced by transmission electron microscopy and X-ray photoelectron spectroscopy. However, the use of the chloride salt was proposed to be more suitable for preparing Ru/TiO2 catalysts, due to the lower photodeposition efficiency observed with acetylacetonate, that did not allow to synthesize Ru nanoparticles with a loading higher than 1 wt.%. Different reaction mechanisms have been proposed for explaining the behaviour of both TiO2-salt systems during the Ru nanoparticle synthesis, involving respectively, both holes and electrons charge carriers in oxidation and reduction steps with acetylacetonate, and the sole photogenerated electrons with chloride.Graphical abstractGraphical abstract for this article
       
  • Au/Rod-like MnO2 catalyst via thermal decomposition of manganite precursor
           for the catalytic oxidation of toluene
    • Abstract: Publication date: Available online 5 July 2018Source: Catalysis TodayAuthor(s): Hua Sun, Xiaolin Yu, Xueqin Yang, Xiuyun Ma, Mengya Lin, Changfang Shao, Yao Zhao, Fuyi Wang, Maofa GeAu/Rod-like MnO2 catalyst was prepared via thermal decomposition of Au/MnOOH precursor. Au nanoparticles (NPs) with an average size of about 3.05 nm were highly dispersed on the MnOOH supports. Au/MnO2-300 catalyst exhibited the best catalytic activity for toluene oxidation due to the abundant surface Mn4+ species, large specific surface area, good low-temperature reducibility and high oxygen species mobility. The further increase of thermal decomposition temperature resulted in the severe sintering of Au NPs, causing the decrease of toluene catalytic activity. The T50 and T90 values for Au/MnO2-300, 400 and 500 catalysts were 202, 207, 210 °C and 205, 210, 215 °C, respectively. The apparent activation energy of Au/MnO2-300 catalyst (61 kJ/mol) was obviously lower than those of Au/MnO2-400 (107.8 kJ/mol) and 500 (141.5 kJ/mol) catalysts. The reaction rates at 185 °C had a decrease tendency from 0.37 to 0.16 mol s−1 gcat−1 with the growth of Au NPs for Au/MnO2-300, 400 and 500 catalysts.Graphical abstractGraphical abstract for this article
       
  • Formation of CeMnxOy/OMS-2 nanocomposite significantly enhances
           UV–vis-infrared light-driven catalytic activity
    • Abstract: Publication date: Available online 5 July 2018Source: Catalysis TodayAuthor(s): Huihui Liu, Yuanzhi Li, Yi Yang, Zhengkang Shi, Qian Zhang, Shaowen Wu, Xiujian ZhaoThe CeMnxOy/OMS-2 nanocomposites were prepared by depositing different amounts of amorphous CeMnxOy on the pure OMS-2 sample by the hydrothermal redox reaction of Ce(NO3)3 and KMnO4. The formation of the CeMnxOy/OMS-2 nanocomposites causes a significant enhancement in the photothermocatalytic activity of OMS-2 for the gas-phase oxidation of benzene under the UV–vis-infrared illumination from a Xe lamp. The optimum CeMnxOy/OMS-2-5.0% nanocomposite exhibits very effective photothermocatalytic activity and very good durability under the UV–vis-infrared illumination. It also exhibits effective photothermocatalytic activity under the visible-infrared and infrared illumination. The significantly enhanced photothermocatalytic activity of the CeMnxOy/OMS-2-5.0% nanocomposite as compared to the pure OMS-2 sample is attributed to the much higher thermocatalytic activity of the former than the latter due to a significant improvement in the reducibility upon the formation of the CeMnxOy/OMS-2-5.0% nanocomposite. A novel photoactivation quite unlike the photocatalysis on the semiconductor photocatalyst such as anatase TiO2 is found to obviously promote the solar-light-driven thermocatalytic activity.Graphical abstractGraphical abstract for this article
       
  • Support effects on NiO-based catalysts for the oxidative dehydrogenation
           (ODH) of ethane
    • Abstract: Publication date: Available online 5 July 2018Source: Catalysis TodayAuthor(s): D. Delgado, R. Sanchís, J.A. Cecilia, E. Rodríguez-Castellón, A. Caballero, B. Solsona, J.M. López NietoWe report on the effect of NiO-support interactions in the chemical nature of Ni species on a series of supported NiO catalysts for the ODH of ethane. SiO2, TiO2-anatase, a high surface area TiO2 and a porous clay heterostructure (PCH) with TiO2 and SiO2 pillars were used as supports, which led to a selectivity to ethylene in the range 30-90 % over supported NiO catalysts. The catalysts were characterized by means of XRD, N2-Adsorption, H2-TPR, XPS and in-situ (under H2 reductive atmosphere) and ex-situ XAS spectroscopy. The catalytic performance of supported materials is discussed in terms of their reducibility and specific reduction kinetics, but also taking into account the specific chemical nature of Ni species on each catalyst. The influence of the particle size and the presence of Ni and O vacancies on the catalytic performance in the ODH of ethane is inferred.Graphical abstractGraphical abstract for this article
       
  • Cu and Pt clusters deposition on TiO2 powders by DC magnetron sputtering
           for photocatalytic hydrogen production
    • Abstract: Publication date: Available online 5 July 2018Source: Catalysis TodayAuthor(s): Massimo Bernareggi, Gian Luca Chiarello, Glen West, Marina Ratova, Anna Maria Ferretti, Peter Kelly, Elena SelliABSTRACTTitanium dioxide-based photocatalyst powders were obtained by deposition of copper and/or platinum clusters by means of pulsed direct current magnetron sputtering with different deposition times and plasma composition during Cu/Pt sputtering. A top-down configuration was employed with the sputtering source facing the powder holder mounted on a shaker mechanism, which continuously mixed the powder during the sputtering process. HRTEM analyses revealed the presence of well dispersed, subnanometric sized metal clusters, even for long deposition times, while XRPD analysis showed no modification of the TiO2 crystal structure upon metal deposition. The so obtained powders were tested as photocatalysts in methanol photo-steam reforming for hydrogen production. The presence of Pt clusters increased the photoactivity with respect to that of bare TiO2. The plasma composition during Cu sputtering was found to strongly affect the photoactivity of the obtained materials, Cu alone deposited as co-catalyst in an Ar-only atmosphere imparting better photoactivity than Cu sputtered in Ar/O2. When the deposition of Cu clusters was coupled with the deposition of Pt clusters, an additive effect of the two metals in increasing TiO2 photoactivity was observed if Cu clusters were sputtered in the absence of oxygen.Graphical Graphical abstract for this article
       
  • Mo-doped BiVO4@reduced graphene oxide composite as an efficient photoanode
           for photoelectrochemical water splitting
    • Abstract: Publication date: Available online 5 July 2018Source: Catalysis TodayAuthor(s): Palyam Subramanyam, T. Vinodkumar, Devadutta Nepak, Melepurath Deepa, Challapalli SubrahmanyamMonoclinic Bismuth vanadate (BiVO4) nanomaterial is an attractive, efficient photoanode for photoelectrochemical (PEC) water splitting due to excellent visible light activity and good photo-chemical stability. However, poor charge separation and low charge carrier mobility hinder the improvement of PEC performance of BiVO4. In this work, molybdenum (Mo)-doped BiVO4@reduced graphene oxide (rGO) nanocomposites are fabricated and their potential to serve as photoanodes for PEC water splitting is evaluated. This composite, by the introduction of Mo-dopant and rGO in BiVO4 enhances the PEC performance for water oxidation for they assist in reducing charge recombination and enhancement of photocurrent. As a result, the Mo-BiVO4@rGO composite photoanode exhibited a photocurrent density of 8.51 mA cm−2 at 1.23 V versus reversible hydrogen electrode (RHE), which is two and four times greater than that of Mo-BiVO4 (5.3 mA cm-2 at 1.23 V versus RHE) and pristine BiVO4 (2.01 mA cm−2 at 1.23 V versus RHE) photoactive electrodes. In addition, good photo-conversion efficiency, low charge transfer resistance and good external quantum efficiency (EQE) are achieved for this ternary nanocomposite. These studies reveal the improved PEC activity for water splitting by the Mo-doped BiVO4@rGO, and indicated that this approach can be used to design more efficient photoanodes for PEC water splitting.Graphical abstractGraphical abstract for this article
       
  • Large-scale pattern fabrication of 3D rGO-Ag@Ag3PO4 hydrogel composite
           photocatalyst with the excellent synergistic effect of adsorption and
           photocatalysis degradation
    • Abstract: Publication date: Available online 5 July 2018Source: Catalysis TodayAuthor(s): Zengyuan Li, Tong Chen, Sen Liu, Mengyu Zhao, Kai Chen, Daimei Chen, Jie ChenA novel visible-light driven 3D porous network structure rGO-Ag@Ag3PO4 (RAA) hydrogel composite photocatalyst with a synergistic effect of adsorption enrichment and photocatalysis degradation has been synthesized by a facile method and characterized by XRD, SEM, TEM, EDS, FTIR, DRS, UV–vis, TG, Raman, and XPS. RAA hydrogel photocatalyst with 3D porous network structure is not only favorable to increasing the absorption property for organic pollutants owing to a larger surface area and π-π conjunction property, but also promotes the separation and transformation of electron-hole pairs due to the good conductivity performance. The RAA hydrogel composite photocatalyst has exhibited the excellent removal capacity of organic pollutants which were about 1.94 and 1.10 times higher than those of bare Ag3PO4 for the removal of MB and 2, 4-CDP in the dynamic system, respectively. The enhancement of removal efficiency was due to a synergistic effect of adsorption enrichment and photocatalysis degradation. The removal rate of RAA hydrogel composite photocatalyst has only a little decrease from 76.04% to 68.51% for 60 h of the photoreaction, showing the relatively good stability. The trapping experiment and ESR showed the main active species were holes.Graphical abstractGraphical abstract for this article
       
  • The production of furfural directly from hemicellulose in lignocellulosic
           biomass: A review
    • Abstract: Publication date: Available online 5 July 2018Source: Catalysis TodayAuthor(s): Yiping Luo, Zheng Li, Xiaoling Li, Xiaofeng Liu, Jiajun Fan, James H. Clark, Changwei HuAs one main component of lignocellulosic biomass, hemicellulose is a promising alternative for the replacement of limited fossil resources to produce furfural, thus preserving a high atom efficiency. However, the complex structure of hemicellulose and the interaction between the other two components in lignocellulosic biomass (cellulose and lignin) make the effective utilization of naturally formed structure of hemicellulose challenging. This review presents an overview of the production of furfural directly from hemicellulose in lignocellulosic biomass with special emphasis on achieving the effective utilization of hemicellulose, which includes the selective dissolution of hemicellulose from lignocellulosic biomass and the selective formation of furfural from hemicellulose derivatives. Whereas the cellulose and lignin structures are retained, which can be utilized separately. Solvents and catalysts are considered as two main factors in this valorization process of hemicellulose.Graphical abstractGraphical abstract for this articleSolvents and catalysts played important roles on the selective dissolution and conversion of hemicellulose in actual biomass to produce furfural with high yield and selectivity.
       
  • Morphological transformations during Fischer-Tropsch synthesis on a
           titania-supported cobalt catalyst
    • Abstract: Publication date: Available online 4 July 2018Source: Catalysis TodayAuthor(s): C.E. Kliewer, S.L. Soled, G. KissDeactivation mechanisms for a rhenium-promoted titania-supported cobalt catalyst are investigated during Fischer-Tropsch (FT) synthesis. Bench-scale reactor tests, chemisorption studies, thermogravimetric analyses (TG), and transmission electron microscopy (TEM) are used to probe environmental effects on catalytic activity.Bench-scale reactor studies show a steady decrease in activity with time. While a fraction of this loss can be recovered with a low temperature reduction (rejuvenation) inside the reactor, multiple data indicate this phenomenon is primarily attributable to water-induced oxidation of small cobalt particles.Data from long-term FT runs indicate the presence of three non-rejuvenable deactivation mechanisms: metal agglomeration, strong metal-support interaction (SMSI), and mixed metal oxide formation. High conversion studies implicate byproduct water in the agglomeration process, and ex-situ TEM data conclusively reveals that growth occurs via a coalescence mechanism. Combined kinetic and chemisorption studies reveal that SMSI results from the gradual buildup of titania decoration on the surface of the active cobalt and is exacerbated with multiple rejuvenation cycles. TGA data indicate that mixed metal oxide formation occurs in long-duration, pilot plant runs. In all cases, the aggregate of reactor kinetic, chemisorption, TG, and TEM results point to chemically-assisted deactivation phenomena attributable to the byproduct water.Graphical abstractGraphical abstract for this articleFour deactivation mechanisms are observed in long duration (~ 6 month) FT synthesis runs involving a Co-Re/TiO2 catalyst: rejuvenable deactivation via small metal particle oxidation and non-rejuvenable deactivation by metal particle growth, strong metal-support interaction (SMSI), and mixed metal oxide formation. Of these, metal particle growth via a chemically-assisted byproduct water-based oxidation is the dominant reason for activity loss.
       
  • Photocatalytic properties of TiO2-loaded porous silica with hierarchical
           macroporous and mesoporous architectures in the degradation of gaseous
           organic molecules
    • Abstract: Publication date: Available online 3 July 2018Source: Catalysis TodayAuthor(s): Takashi Kamegawa, Yasushi Ishiguro, Hiromi YamashitaAs an advanced support of TiO2 photocatalyst, mesoporous silica (MS) with hierarchical macroporous architecture (MMS) was prepared by applying templating synthesis techniques. Colloidal crystal of spherical poly(methyl methacrylate) (PMMA) particles and organic surfactant was used for construction of two types of pores with different size scales. The porous structure and state of TiO2 was investigated by various characterization techniques. Mesoporous and macroporous structure of MMS with interconnecting networks was maintained even after loading of TiO2 particles. The unique properties of macroporous structure were observed in the adsorption of acetone gas and 2-propanol gas. In comparison of TiO2-loaded MMS and MS (denoted as TiO2/MMS and TiO2/MS), TiO2/MMS showed a high adsorption rate and a large adsorbed amount in the case of 2-propanol at low and high relative pressure, respectively. However, each profile in the case of acetone was almost same in both samples. Based on the advantageous porous structure, TiO2/MMS also exhibited a good photocatalytic performance in the degradation of 2-propanol in gas phase under UV light irradiation.Graphical abstractGraphical abstract for this article
       
  • Micropore diffusivities of NO and NH3 in Cu-ZSM-5 and their
           effect on NH3-SCR
    • Abstract: Publication date: Available online 2 July 2018Source: Catalysis TodayAuthor(s): Yuta Nakasaka, Takumi Kanda, Ken-ichi Shimizu, Kenichi Kon, Gen Shibata, Takao MasudaMicropore diffusivities of NO and NH3 were experimentally measured for Cu-ZSM-5 using constant volumetric method at a temperature range from 373 K to 423 K. Intracrystalline diffusivities and effective diffusivities of NO were lower than those of NH3, and the activation energy for intracrystalline diffusivity of NO (21 kJ mol-1) was higher than that of NH3 (6.3 kJ mol-1). The intracrystalline diffusivity of NO in Cu-ZSM-5 catalysts at 373 K was independent of Cu content and Si/Al ratio of Cu-ZSM-5. We proposed an equation for calculation of effective diffusivity of NO in Cu-ZSM-5 which was validated by the experimental data. Kinetic studies for NH3-SCR and NH3 oxidation were carried out using Cu-ZSM-5 with different crystal thickness. The apparent reaction rate of NH3-SCR at 523 K depended on the zeolite crystal thickness; the rates by a small Cu-ZSM-5 (0.088 μm) was 2.75 times higher than that by a large crystal catalyst (2.7 μm), corresponding to the effectiveness factor of 0.36. The apparent reaction rate of NH3 oxidation did not depend on the zeolite crystal size. It is concluded that NH3-SCR is controlled by intracrystalline diffusion of NO, or in other words, the active sites in zeolite crystal are not fully utilized due to the NO diffusion limitation. The effective diffusivity of NO in Cu-ZSM-5 estimated by the catalytic study was close to that calculated using the NO diffusivity results, which supported our conclusion.Graphical abstractGraphical abstract for this article
       
  • 1D-Co3O4, 2D-Co3O4, 3D-Co3O4 for catalytic oxidation of toluene
    • Abstract: Publication date: Available online 2 July 2018Source: Catalysis TodayAuthor(s): Quanming Ren, Zhentao Feng, Shengpeng Mo, Chunlei Huang, Shujun Li, Weixia Zhang, Limin Chen, Mingli Fu, Junliang Wu, Daiqi YeA facile template-free hydrothermal method was applied to successfully synthesize a series of bulk cobalt oxides with different morphologies (1D-Co3O4 nanoneedle, 2D-Co3O4 nanoplate, and 3D-Co3O4 nanoflower). The catalytic activity for the toluene combustion over various types of catalysts was investigated. The 3D-Co3O4 nanoflower performed the excellent activity and the temperature required for achieving a toluene conversion of 90 % (T90%) at approximately 238 °C with the activity energy (Ea) of 71.6 KJ mol−1, which was 19 ℃ lower than that of 1D-Co3O4 nanoneedle with Ea of 97.1 KJ mol−1 at a space velocity (WHSV = 48, 000 mL g−1  h−1). The effect of shape on the physicochemical properties of the Co3O4 catalysts were characterized by various analytical techniques. It has been found that large specific surface area, low temperature reducibility, highly defective structure with abundant surface active oxygen species and rich Co3+ cationic species were responsible for the excellent catalytic performance of 3D-Co3O4 nanoflower. In addition, complete conversion of toluene had remained the same after 3D-Co3O4 nanoflower was observed for 120 h, suggesting it exhibited the long-term stability for toluene combustion. Therefore, 3D-Co3O4 nanoflower might be a potential non-noble catalyst in practical application.Graphical abstractGraphical abstract for this article
       
  • The effect of metal (Nb, Ru, Pd, Pt) supported on SBA-16 on the
           hydrodeoxygenation reaction of phenol
    • Abstract: Publication date: Available online 2 July 2018Source: Catalysis TodayAuthor(s): Agnieszka Feliczak-Guzik, Paulina Szczyglewska, Izabela NowakOrdered silica materials of SBA-16 type were synthesized, characterized as to their physicochemical properties and used as supports of the active phases which were niobium, ruthenium, palladium or platinum ions. Physicochemical properties of the systems obtained were determined by XRD, N2 sorption and TEM methods. Then the materials were used as catalytic systems in the process of phenol hydrodeoxygenation. The reaction was carried out in the range 90-130 °Cunder hydrogen pressure of 2,5-6 MPa. The effects of three variables on the course of the process were evaluated:(i) temperature, (ii) hydrogen pressure, (iii) type of active phase (metal). The main product of the reaction with the use of catalysts SBA-16/Ru, SBA-16/Pd, SBA-16/Pt was 2,4-dimethylhexane, while when using SBA-16/Nb, the main product was 1-methoxy-2-hexene. In the reaction conditions applied, 100% of phenol conversion was achieved. Direct effect of the reaction conditions, i.e., temperature and hydrogen pressure on the course of the process was observed.Graphical abstractGraphical abstract for this article
       
  • Syntheses and Characterization of α-Keggin- and α2-Dawson-type
           Diplatinum(II)-coordinated Polyoxotungstates: Effects of Skeletal
           Structure, Internal Element, and Nitrogen-containing Ligand Coordinated to
           the Platinum Center for Hydrogen Production from Water under Light
           Irradiation
    • Abstract: Publication date: Available online 2 July 2018Source: Catalysis TodayAuthor(s): Chika Nozaki Kato, Shunsaku Suzuki, Takayuki Mizuno, Yuki Ihara, Akihiro Kurihara, Shunpei NagataniThe tetramethylammonium and cesium salts of diplatinum(II) complexes composed of mono-lacunary α-Keggin- and α2-Dawson-type polyoxotungstates, [(CH3)4N]4H[α-AlW11O39{cis-Pt(NH3)2}2]⋅11H2O (TMA-AlW11-Pt-NH3), [(CH3)4N]4H[α-BW11O39{cis-Pt(NH3)2}2]⋅9H2O (TMA-BW11-Pt-NH3), Cs4[α-GeW11O39{Pt(bpy)}2]∙10H2O (bpy = 2,2’-bipyridine; Cs-GeW11-Pt-bpy), Cs3.5H0.5[α-GeW11O39{Pt(phen)}2]∙3H2O (phen = 1,10-phenanthroline; Cs-GeW11-Pt-phen), and Cs6[α2-P2W17O61{cis-Pt(NH3)2}2]∙13H2O (Cs-P2W17-Pt-NH3), were synthesized and characterized by X-ray crystallography, elemental analysis, TG/DTA, FTIR, and solution {1H and 31P} NMR spectroscopy. The characterization results showed that the two platinum(II) moieties, [cis-Pt(NH3)2]2+, [Pt(bpy)]2+, and [Pt(phen)]2+, were coordinated to the mono-vacant site of [XW11O39](12−n)− (Xn+ = Al3+, B3+, and Ge4+) and [α2-P2W17O61]10−. When the eight platinum(II) compounds, [(CH3)4N]3[α-PW11O39{cis-Pt(NH3)2}2]⋅10H2O (TMA-PW11-Pt-NH3), [(CH3)4N]4[α-SiW11O39{cis-Pt(NH3)2}2]·13H2O (TMA-SiW11-Pt-NH3), [(CH3)4N]4[α-GeW11O39{cis-Pt(NH3)2}2]·11H2O (TMA-GeW11-Pt-NH3), TMA-AlW11-Pt-NH3, TMA-BW11-Pt-NH3, Cs-GeW11-Pt-bpy, Cs-GeW11-Pt-phen, and Cs-P2W17-Pt-NH3 were used as photocatalysts for hydrogen evolution from aqueous triethanolamine (TEOA) solution under the light irradiation, Cs-P2W17-Pt-NH3 exhibited the highest activities among the eight diplatinum(II) compounds.Graphical abstractGraphical abstract for this article
       
  • Tungstophosphoric acid supported on mesoporouus niobiumoxophosphate: An
           efficient solid acid catalyst for etherification of
           5-hydroxymethylfurfural to 5-ethoxymethylfurfural
    • Abstract: Publication date: Available online 2 July 2018Source: Catalysis TodayAuthor(s): P. Krishna Kumari, B. Srinivasa Rao, D. Dhana Lakshmi, N. Ruthwik Sai Paramesh, C. Sumana, N. LingaiahTungstophosphoric (TPA) supported on mesoporouus niobiumoxophosphate (NbP) catalysts were prepared with different loadings. The synthesized materials employed as heterogeneous solid acid catalysts for selective etherification of 5-hydroxymethylfurfural to 5-ethoxymethylfurfural. Physico-chemical properties of the catalysts were obtained by different spectroscopic techniques and their results exposed that TPA was a highly dispersed state on NbP and acidity of the catalyst enhanced due to its dispersion. The higher catalytic performance can be allied to the total acidity of the catalysts with appropriate number of Brønsted-Lewis acid sites which were directed by the contact and dispersion of TPA on support. Different reaction parameters were premeditated and 25 wt% TPA/NbP catalyst exhibited highest catalytic activity with 95% of HMF conversion and 89% of EMF yield. The catalyst is reusable without noticeable turn down in catalytic performance up to five cycles. A kinetic model for etherification of HMF was also derived.Graphical abstractGraphical abstract for this article
       
  • In-situ FTIR-DRS investigation on shallow trap state of Cu-doped
           TiO2 Photocatalyst
    • Abstract: Publication date: Available online 2 July 2018Source: Catalysis TodayAuthor(s): Lihong Zhang, Bing Han, Peifu Cheng, Yun Hang HuIt is important to characterize photocatalysts by in-situ techniques. In this work, the high pressure temperature-programmed in-situ Fourier Transform Infrared Diffuse Reflection Spectroscopy (FTIR-DRS) was employed to evaluate shallow trap states in Cu-doped TiO2 photocatalyst. It was demonstrated that the formation of the shallow trap state by reduction is much easier for CuO/TiO2 than pure TiO2. Furthermore, the formation temperature of the shallow trap state for CuO/TiO2 is the same as its starting reduction temperature of Cu2+ to Cu+, which indicates that the generated shallow trap state might be Cu+.Graphic Graphical abstract for this articleIn-situ FTIR shows that the reduction of CuO/TiO2 by hydrogen can generate the shallow trap state of Cu+.
       
  • Pt x Co/meso-MnO y : Highly efficient catalysts for low-temperature
           methanol combustion
    • Abstract: Publication date: Available online 2 July 2018Source: Catalysis TodayAuthor(s): Jun Yang, Yuxi Liu, Jiguang Deng, Shaohua Xie, Zhiquan Hou, Xingtian Zhao, Kunfeng Zhang, Zhuo Han, Hongxing DaiThe KIT-6-templating and polyvinyl alcohol-protected NaBH4 reduction methods were adopted to prepare the mesoporous manganese oxide (meso-MnOy) and its supported Co, Pt, and PtxCo catalysts, respectively. Numerous techniques were used to characterize the physicochemical properties of the materials. Catalytic performance of the samples was evaluated for methanol combustion. All of the samples possessed a three-dimensionally ordered mesoporous structure and a surface area of 94–110 m2/g. The Co, Pt, and PtxCo nanoparticles (NPs) with an average size of 2.2–3.1 nm were uniformly dispersed on the surface of meso-MnOy. The 0.70 wt% Pt2.42Co/meso-MnOy sample performed the best: the T50% and T90% (temperatures required for achieving methanol conversions of 50 and 90 %, respectively) were 50 and 86 °C at a space velocity of 80,000 mL/(g h). The partial deactivation of the 0.70Pt2.42Co/meso-MnOy sample due to water vapor or carbon dioxide introduction was reversible. It is concluded that the excellent catalytic activity of 0.70 wt% Pt2.42Co/meso-MnOy was associated with its highly dispersed Pt2.42Co alloy NPs, high adsorbed oxygen species concentration, good low-temperature reducibility, and strong interaction between Pt2.42Co alloy NPs and meso-MnOy.Graphical Graphical abstract for this articleMesoporous manganese oxide (meso-MnOy) and its supported Co, Pt, and PtxCo catalysts are prepared via the KIT-6-templating and PVA-protected reduction routes, respectively. The excellent catalytic activity of 0.70 wt% Pt2.42Co/meso-MnOy is associated with its highly dispersed Pt2.42Co alloy NPs, high adsorbed oxygen species concentration, good low-temperature reducibility, and strong interaction between Pt2.42Co NPs and meso-MnOy.
       
  • Tailoring the Crystallite Size of Co3O4/SiO2 Catalyst Using Organic-Metal
           Matrix Method
    • Abstract: Publication date: Available online 2 July 2018Source: Catalysis TodayAuthor(s): Xiaoqin Qin, Benzhen Yao, Sergio Gonzalez-Cortes, Yongxiang Zhao, Tiancun XiaoIn this work, a series of SiO2 supported Co catalyst have been prepared by adding urea or ruthenium to the cobalt precursor solution compared with the catalysts prepared without using urea. The characterization results show that cobalt is present as Co3O4 over the silica supports. The addition of urea to the catalyst precursor helps to generate smaller crystallite even at very high cobalt loading, while impregnation without using urea results in larger crystallite size as Co loading increases. Likewise, the addition of Ru to the catalyst precursor leads to a more uniform crystallite of Co3O4, and can help to lower the Co3O4 crystallite size to some extent, which has the similar effect on the catalyst prepared with urea. We have also shown that the support pore size and volume do have significant effect on the crystallite size of the cobalt oxide. The catalytic performances of the Co/SiO2 catalysts prepared with and without adding urea have been evaluated for Fischer Tropsch synthesis and the catalyst prepared using urea demonstrates significantly improved catalyst activity as well as selectivity to C5+.Graphical abstractGraphical abstract for this articleComparison of the change of Co3O4 crystallite size with the cobalt loading over SiO2 supports prepared using different method.
       
  • Ferric porphyrin–based polymers for electrochemical oxygen reduction
    • Abstract: Publication date: Available online 2 July 2018Source: Catalysis TodayAuthor(s): Subhabrata Banerjee, Yuta NabaeElectrochemical oxygen reduction reaction (ORR) is a very important reaction for green and sustainable chemistry. Herein, we report the design and synthesis of a semi-crystalline metallopolymer consisting of ferric porphyrin–based building blocks immobilized by organic linkers (viz. various dialdehydes) through rigid imine bonds. All the materials thus obtained showed moderate to high ORR performance in rotating ring-disk electrode voltammetry with oxygen-saturated 0.5 M H2SO4 and 0.1 M KOH.Graphical abstractGraphical abstract for this article
       
  • Perovskite-based photocatalysts for organic contaminants removal: Current
           status and future perspectives
    • Abstract: Publication date: Available online 30 June 2018Source: Catalysis TodayAuthor(s): Jiejing Kong, Ting Yang, Zebao Rui, Hongbing JiThe development of new generation photocatalytic materials for the organic contaminants removal has been a research focus. Perovskite and perovskite-related structures offer a broad scope in designing novel photocatalysts for this process. The present review summarizes and highlights the state-of-the-art progress of third-generation photocatalysts perovskite and perovskite-related semiconductors, and their application for the photocatalytic decomposition of both waterborne and airborne organic contaminants. Special attention is paid to the design strategies for promoting the photocatalytic performance of perovskite and perovskite-related materials, including ion doping/substitution, noble metal decoration, heterojunctions formation and morphology regulation. Future perspectives of perovskite-related photocatalysts are also included in this review.Graphical abstractGraphical abstract for this article
       
  • Insights into the reaction pathway of hydrodeoxygenation of dibenzofuran
           over MgO supported noble-metals catalysts
    • Abstract: Publication date: Available online 28 June 2018Source: Catalysis TodayAuthor(s): Jie Zhang, Chuang Li, Xiao Chen, Weixiang Guan, Changhai LiangConversion of oxygen-containing compounds derived from lignin arises wide interest due to fossil-derived resources consumption and growing environmental concerns. In this work, hydrodeoxygenation (HDO) of dibenzofuran (DBF) was studied over high-surface-area MgO supported Pt, Pd and Ru catalysts at 370 °C and 1.0 MPa. It was determined that the active metals not only affect the catalytic activity, but also change the reaction pathway of HDO of DBF. The intrinsic activity (TOF) of MgO supported catalysts follows the trend: Pt/MgO (0.36 s−1)> Ru/MgO (0.29 s−1)> Pd/MgO (0.09 s−1), companied by the increasing activate barrier. Pt has a high activity in the hydrogenation of DBF, and exhibits a perfect deoxygenation activity followed by hydrogenation (HYD) pathway. Ru shows better cleavage ability of CaromaticO bond and the removal of oxygen from DBF mainly occurs via direct deoxygenation (DDO) pathway. The increased Pt loadings largely promote the conversion of DBF by enhancing both HYD and DDO pathways. In addition, more direct cleavage of CaromaticO bond occurs at higher temperature and the production of aromatics by the DDO pathway prefers the relatively low reaction pressure. Based on the pseudo-first-order kinetics, the analysis of the fitted reaction rate constant shows that the DDO selectivity follows the order: Ru/MgO > Pd/MgO > Pt/MgO, which depends on the capacity of active metals to the cleavage of CaromaticO bond and the hydrogenation of aromatic ring.Graphical abstractGraphical abstract for this article
       
  • Esterification of oleic acid to biodiesel catalyzed by a highly acidic
           carbonaceous catalyst
    • Abstract: Publication date: Available online 28 June 2018Source: Catalysis TodayAuthor(s): Yi-Tong Wang, Zhen Fang, Fan ZhangCarbonaceous catalyst, with a variety of acid sites, was successfully synthesized by a two-step method at low temperature. The synthesized catalyst (Zr-SO3H@CMC) was characterized by elemental analysis, XRD, ICP-OES, FT-IR, BET, SEM-EDX and Boehm titration. It had high total acid content (8.45 mmol/g) for oleic acid esterification with high biodiesel yields (> 99%) at 40-90 °C. Under conditions of 90 °C, 20/1 methanol/oleic acid molar ratio, 5 wt% catalyst and 2 h reaction time, biodiesel yield of> 87% was achieved after 10 cycles of use. At lower temperatures (40, 50 and 60 °C), biodiesel yield still reached 82 %, 93 % and 90 % after 3 cycles, respectively. The high activity of Zr-SO3H@CMC benefited from low activation energy of 24.7 KJ/mol. It shows potential application for esterification of free fatty acids or pretreatment of oils with high acid value for the green production of biodiesel.Graphical abstractGraphical abstract for this articleCarbonaceous acid catalyst with high acid content was synthesized by metal (Zr) ion chelation and sulfonation of sodium carboxymethylcellulose. It catalyzed the esterification of oleic acid, with biodiesel yield> 99% at 40-90 °C (activation energy of 24.7 KJ/mol).
       
  • Photocatalytic properties of layer-by-layer thin films of hexaniobate
           nanoscrolls
    • Abstract: Publication date: Available online 26 June 2018Source: Catalysis TodayAuthor(s): Barbara N. Nunes, Christoph Haisch, Alexei V. Emeline, Detlef W. Bahnemann, Antonio Otavio T. PatrocinioHigh efficient photocatalytic surfaces were obtained through the layer-by-layer (LbL) deposition of hexaniobate nanoscrolls on conductive glasses. These films were deposited by alternative immersions of the substrate into exfoliated hexaniobated suspensions (pH = 8) and poly(allylamine hydrochloride) solutions (pH = 4). The organic species were further removed by thermal treatment leading to a fuzzy assembly of hexaniobate nanoscrolls. Pre-adsorption of [Pt(NH3)4]2+ cations on the niobate layers allows the production of metallic Pt nanoclusters on the film layers. The Pt-modified films exhibited apparent quantum yields of (4.0 ± 0.5) % for H2 evolution from water/methanol mixtures under UV-A irraditation. The H2 evolution rates varied linearly with the number of deposited bilayers, indicating that no active sites are lost as the film is grown. The photoelectrochemical properties of the films reveal that the small size of the hole scavenger and its easy diffusion into the hexaniobate layers are key aspects for the photocatalytic activity. In the absence of alcohols as hole scavengers, irradiation of the hexaniobate LbL films in aqueous solutions leads to the production of surface-bound peroxides that limit the photocatalytic water splitting ability of these materials. The results presented here provide evidence for the effectiveness of the LbL technique to deposit thin films of layered materials retaining their interesting adsorption chemistry. This methodology can be further employed for the development of highly active photocatalytic surfaces.Graphical abstractGraphical abstract for this article
       
  • Tuning the composition of porous resin-templated TiO2 macrobeads for
           optimized photocatalytic performance
    • Abstract: Publication date: Available online 25 June 2018Source: Catalysis TodayAuthor(s): Q.A. Naqvi, M. Ratova, R. Klaysri, P.J. Kelly, M. Edge, S. Potgieter-Vermaak, L. ToshevaTiO2 in the form of macroscopic beads was prepared by resin templating. Anion-exchange macroporous resin beads were treated with a synthesis gel containing titanium isopropoxide, iso-propanol and diluted (0–5 wt.%) tetrapropylammonium hydroxide (TPAOH) aqueous solutions. The Ti-resin composite obtained was calcined at 600 °C to remove the resin. The presence of TPAOH in the precursor solution was essential for producing intact TiO2 beads. The use of 1–1.5 wt.% TPAOH resulted in anatase beads, whereas further increase in the TPAOH content promoted the anatase to rutile phase transformations. Decreasing the heating rate used during calcination also resulted in changes in the TiO2 composition from pure anatase (16 °C min−1 heating rate) to anatase with rutile impurities (0.5 °C min−1 heating rate). The photocatalytic activity of the TiO2 beads was evaluated for the degradation of acetone under ultraviolet irradiation. A high activity was displayed by the TiO2 samples composed of anatase with rutile impurities, whereas the activity was lower for pure anatase samples or samples containing mainly rutile. The TiO2 beads showed higher rates of charge carrier generation and slower charge trapping/recombination rates compared to a reference Cristal ACTiV™ PC500. In addition, the TiO2 beads could be used in at least five consecutive catalytic cycles without any in-between cycle treatment, without significant changes in their activity. The TiO2 beads prepared in this work are beneficial for photocatalytic applications in the gas-phase compared to powders due to easy handling, reduced pressure drop and attrition resistance.Graphical abstractGraphical abstract for this article
       
  • Facile synthesis of high-surface area platinum-doped ceria for low
           temperature CO oxidation
    • Abstract: Publication date: Available online 23 June 2018Source: Catalysis TodayAuthor(s): Suresh Gatla, Daniel Aubert, Valérie Flaud, Rémi Grosjean, Thomas Lunkenbein, Olivier Mathon, Sakura Pascarelli, Helena KaperUsing a simple slow decomposition method of nitrate precursors, high-surface area platinum-doped ceria with a crystallite size of 9 nm can be prepared. The catalytic performance of the compound can be tuned by changing the reduction temperature under hydrogen (300 °C, 500 °C and 700 °C). The catalyst treated at 300 °C shows the best catalytic performance, being active at room temperature. The materials were analysed using a combination of structural characterization methods (X-ray diffraction (XRD), nitrogen physisorption, high angle annular dark field scanning transmission electron microscopy (HAADF-STEM)), surface sensitive methods (X-ray photoelectron spectroscopy (XPS), H2-chemisorption and H2-temperature-programmed reduction (TPR)) and X-ray absorption fluorescence spectroscopy (XAFS). HAADF-STEM and XAFS analysis suggests successful doping of platinum in the ceria lattice. After pretreatment at 300 °C, the situation is slightly different. While no defined platinum nanoparticles can be identified on the surface, some platinum is in a reduced state (XPS, H2-chemisorption).Graphical abstractGraphical abstract for this article
       
  • Thermally stable Ag/Al2O3 confined catalysts with high diffusion-induced
           oxidation activity
    • Abstract: Publication date: Available online 23 June 2018Source: Catalysis TodayAuthor(s): Houlin Wang, Shuting Luo, Xinghao Li, Wei Liu, Xiaodong Wu, Duan Weng, Shuang LiuDeveloping catalysts with high cost-efficiency, good oxidation activities and strong thermal resistance is an ongoing task. Herein, we present the design and synthesis of confined catalysts with Ag protected by alumina. Thermal treatment at 800 °C for 10 h caused neither silver loss nor deactivation of this catalyst. Instead, nano-particles of Ag formed because of the heat/O2-derived ripening. These highly dispersed silver species and the catalyst’s mesoporous structure worked in tandem to achieve good catalytic performance for oxidation reactions, which made the aged sample a good candidate as CO elimination and gasoline particulate filter catalysts.Graphical abstractGraphical abstract for this article
       
  • Deactivation behavior on VPO and VPO-Zr catalysts in the aldol
           condensation of methyl acetate and formaldehyde
    • Abstract: Publication date: Available online 22 June 2018Source: Catalysis TodayAuthor(s): Dan Yang, Gang Wang, Hui Wu, Xinpeng Guo, Suojiang Zhang, Zengxi Li, Chunshan LiImprovement in activity for the Zr doped VPO catalyst appears to be a general observation in aldol condensation of methyl acetate and formaldehyde to methyl acrylate. The deactivation behavior significantly differs between VPO and VPO-Zr catalysts. In this work, the deactivation/reactivation behavior and carbon formation in aldol condensation on VPO and VPO-Zr catalysts were investigated. After partial deactivation of the conversion of methyl acetate and formaldehyde to methyl acrylate with a fixed-bed reactor, the deactivated catalysts were fractionated from the reactor. The samples were then analyzed by spectroscopic techniques, gas adsorption measurements and thermogravimetry. The VPO-Zr catalyst showed differences in deactivation/reactivation behavior from the VPO catalyst under same reaction conditions. This finding could be partially ascribed to different coke locations in the deactivated catalysts with varied porosity. The IV4+/IV5+ ratio of V atom remarkably differed among fresh, used, and refreshed catalysts, which could be a key factor affecting catalyst deactivation. The relations of carbon formation and reaction time were fitted by empirical Voorhies equation over VPO and VPO-Zr catalysts. 1Graphical abstractGraphical abstract for this article
       
  • Formaldehyde CWO with gold nanoparticles in a forced through flow
           catalytic-membrane reactor
    • Abstract: Publication date: Available online 20 June 2018Source: Catalysis TodayAuthor(s): B. Martínez-Barrera, M. Gutiérrez-Arzaluz, J.A. Montoya de la Fuente, M. Romero-Romo, M. Torres-RodríguezAbstractA forced through flow membrane-reactor was used to study the formaldehyde catalytic oxidation process, dissolved in oxygen-saturated aqueous solution. The commercial support was modified layer by layer with polycations and polyanions; the active phase of the catalytic membrane was gold nanoparticles dispersed over the macroporous surfaces of the membrane. Formaldehyde oxidation was performed at 30 and 60 °C with three different formaldehyde concentrations, namely: 100, 300 and 500 ppm. The best performance 59% conversion was achieved for an initial 500 ppm after 240 reaction minutes. The reaction products were determined by GC. The catalytic membrane reactor shows good performance for the removal of formaldehyde at low temperature.
       
  • Comparative study of acid-basic properties of MCF impregnated with niobium
           and cerium species
    • Abstract: Publication date: Available online 20 June 2018Source: Catalysis TodayAuthor(s): Katarzyna Stawicka, Piotr Decyk, Anna Wojtaszek-Gurdak, Maria ZiolekNiobium and cerium dopants of mesoporous cellular foams, MCF, have been recently considered as promoters enhancing the basicity of amino-organosilanes anchored to the supports. Thus, the knowledge of acid-basic properties of niobium and cerium containing MCFs is important. Therefore, in this work monometallic (Ce and Nb) and bimetallic (Ce+Nb) materials based on MCF were investigated by means of NO and pyridine adsorption combined with infrared (FTIR) and electron spin resonance (ESR) spectroscopies as well as test reactions. The properties of bimetallic materials strongly depended on the method of impregnation (one-pot vs. step-by-step procedure). If niobium was included in step-by-step method (first niobium and next cerium sources – Ce/Nb/MCF) the Nb species were incorporated to silica skeleton and ceria surrounded some of the framework niobium species (NbO-) enhancing the acidic strength of tetra-coordinated niobium cations playing the role of Lewis acid sites (LAS). One-pot modification (simultaneous impregnation with Nb and Ce sources – CeNb/MCF) resulted in the formation of niobium and cerium oxides showing synergistic interaction. In this system ceria was more defected than in Ce/Nb/MCF sample and acidic strength of niobium species (LAS) was lower.Graphical abstractGraphical abstract for this article
       
  • Effect of chlorine elimination from Pt-Sn catalyst on the behavior of
           hydrocarbon reconstruction in propane dehydrogenation
    • Abstract: Publication date: Available online 20 June 2018Source: Catalysis TodayAuthor(s): Haijuan Zhang, Hai Wan, Yue Zhao, Weiqiang WangThe effect of chlorine elimination from Pt-Sn catalyst on the behavior of hydrocarbon reconstruction in propane dehydrogenation was investigated. The results showed that the chlorine elimination significantly affects multiple characteristics of the catalysts, the type of Pt active phases, and the behavior of hydrocarbon reconstruction. There was no apparent change in catalyst structure. In contrast, the acidity of the catalyst, its specific surface area, and pore volume remarkably decreased whereas its mean pore diameter increased under the same conditions. The degree of Pt sintering, which is disadvantageous to the reaction, was also aggravated. The chlorine elimination also influenced the behavior of hydrocarbon reconstruction in propane dehydrogenation and demonstrated a crucial function in determining selectivity as evidenced by coking experiments. In this work, a strong correlation was established to demonstrate the relation between the structure of Pt active phase and the behavior of hydrocarbon reconstruction in propane dehydrogenation. It is an optimum progress that the chlorine elimination conditions of the Pt active phases centered on the Pt(100) surfaces and the PtSnK/Al2O3 exhibited the best catalytic performance and a low coking rate. Finally, a new model was established to describe the influence of chlorine elimination on the interactions between Pt and SnOx.Graphical Graphical abstract for this article
       
  • Hydrogen production through hydrocarbon fuel reforming processes over Ni
           based catalysts
    • Abstract: Publication date: Available online 20 June 2018Source: Catalysis TodayAuthor(s): Z.R. Ismagilov, E.V. Matus, I.Z. Ismagilov, O.B. Sukhova, S.A. Yashnik, V.A. Ushakov, M.A. KerzhentsevHydrogen production through autothermal reforming (ATR) of hydrocarbon fuels (ethanol, methane) over Ni-based catalysts was studied with a special focus on the role of metal-support interaction. The strength of Ni-support interaction was regulated by means of tailored modification of cerium oxide and aluminum oxide supports. The electronic, redox and structural properties of pre- and post-reaction Ni/Ce1-xMxOy and Ni/Ce1-xMxOy/Al2O3 (M = Zr, Gd, La, Mg) catalysts were studied in detail by TG-DTA, BET, XRD, HRTEM-EDX, HAADF-STEM, TPR, XPS and UV–vis DRS methods. It was found that the mode of Ni-support interaction controls the state, dispersion, and reducibility of Ni active component, and consequently, catalyst performance in ATR of hydrocarbon fuels. Among the tested modifiers (M = Zr, Gd, La, Mg), La has a more pronounced positive effect on the state and functionality of Ni/Ce1-xMxOy and Ni/Ce1-xMxOy/Al2O3 catalysts. The introduction of La as a modifier in the support composition enhances the metal-support interaction, which leads to a diminution of Nin+ reducibility. On the other hand, the improvement of the Ni dispersion and catalyst stability under the ATR reactions is achieved. The addition of a Pd-promoter makes it possible to optimize the reducibility of Nin+ strongly interacting with the support and provides the ability of Ni catalysts to the self-activation. The optimal support composition for Ni nanoparticles was designed that provides hydrogen yields which are close to the thermodynamic equilibrium values: ∼55% (Ce0.8La0.2O1.9, АTP C2H5OH at 600оC) and ∼65% (30Ce0.2Zr0.2La0.6O1.7/Al2O3, АTP CH4 at 850оC).Graphical abstractGraphical abstract for this article
       
  • Single-phase mixed molybdenum-tungsten carbides: Synthesis,
           characterization and catalytic activity for toluene conversion
    • Abstract: Publication date: Available online 20 June 2018Source: Catalysis TodayAuthor(s): Ali Mehdad, Rolf E. Jentoft, Friederike C. JentoftA series of single-phase mixed metal carbides of molybdenum and tungsten (Mo2-xWxC, 0 
       
  • Effect of CeO2 morphologies on toluene catalytic combustion
    • Abstract: Publication date: Available online 20 June 2018Source: Catalysis TodayAuthor(s): Zhentao Feng, Quanming Ren, Ruosi Peng, Shengpeng Mo, Mingyuan Zhang, Mingli Fu, Limin Chen, Daiqi YeCatalytic combustion is an efficient and economic technology to eliminate toluene, and CeO2 shows very good performance in this kind of reactions. In this work, three kinds of CeO2 catalysts with different morphologies (rod, hollow sphere and cube) have been prepared, and there performances for toluene catalytic combustion were compared. It is found that CeO2-HS shows the best catalytic activities for toluene degradation. Toluene conversion could get 90% at 207 °C. That’s because CeO2-HS catalyst have largest surface area and most oxygen vacancies, which are vital for toluene catalytic oxidation. CeO2-HS also shows very good catalyst stability, reusability and excellent tolerance to water.Graphical abstractGraphical abstract for this article
       
  • On developing ferrisilicate catalysts supported on silicon carbide (SiC)
           foam catalysts for continuous catalytic wet peroxide oxidation (CWPO)
           reactions
    • Abstract: Publication date: Available online 19 June 2018Source: Catalysis TodayAuthor(s): Xiaoxia Ou, Fotios Pilitsis, Ninghui Xu, S. F. Rebecca Taylor, John Warren, Arthur Garforth, Jinsong Zhang, Christopher Hardacre, Yilai Jiao, Xiaolei FanFe supported catalysts show great promise for enabling practical environmental catalysis, exemplified by the catalytic wet peroxide oxidation (CWPO) process. In order to mitigate the Fe leaching issue, a strategy of assembling zeolitic coatings with intraframework Fe (ferrisilicate) on SiC foams was developed, showing a good stability in CWPO and a low Fe leaching of 2.0 mg l−1. Direct hydrothermal synthesis of ferrisilicate/SiC foam composites was systematically studied, showing that their characteristics depend on the growth time, pH value and iron concentration of the growth solution. Selected ferrisilicate/SiC foam composite was evaluated using the continuous CWPO of phenolic aqueous solution at 60 °C. The open-cell size of SiC foam was varied between 800 and 2,000 μm and showed insignificant effect on the hydrodynamics of the flow process at 1 ml min −1, but the process efficiency in terms of phenol and total-organic-carbon (TOC) conversions was favored by a high surface-to-volume ratio (i.e. small open-cell sizes). Ferrisilicate/SiC foam catalysts (average open-cell size = 800 μm) showed good stability in the model system with the stable conversions of phenol (97%), H2O2 (84%) and TOC (37%) over 24 h time-on-stream.Graphical abstractGraphical abstract for this article
       
  • Methanolysis of Simarouba Glauca DC oil with hydrotalcite-type
           ZnCuAl catalysts
    • Abstract: Publication date: Available online 19 June 2018Source: Catalysis TodayAuthor(s): Pastora Salinas Hernández, Fernando Morales Anzures, Raúl Pérez Hernández, Francisco Tzompzntzi Morales, Mario A. Romero RomoThe methanolysis of Simarouba Glauca DC oil, was studied using ZnCuAl layered double hydroxides catalysts prepared through urea hydrolysis. The influence of calcination temperature was investigated over the textural properties and catalytic activity of the ZnCuAl catalysts. The solids were pretreated at different calcination temperatures, followed by their characterization by means of XRD, SEM, FT-IR, CO2-TPD, decomposition of 2-propanol and their textural properties assessed with the aid of N2 adsorption and elemental analysis with ICP-MS. The reaction products were studied through FT-IR and gas chromatography.The XRD results showed formation of a hydrotalcite-type material after drying at 100 °C, although thermal treatment at temperatures greater than 200 °C led to formation of a metal oxides mixture. FT-IR allowed checking the evolution of the OH–, CO32– and NO3– groups after thermal treatment, which caused main changes on the basic propeties of the catalysts, evidenced through the CO2-TPD and decomposition of 2-propanol results. The catalyst calcined at 300 °C rendered a larger yield toward biodiesel production during methanolysis of the Simarouba Glauca DC oil, which is atributed to the presence of a larger concentration of medium strength basic sites. The ZnCuAl-300 catalyst showed a 6% decrease in the yield toward biodiesel production after being subjected to three reaction cycles, which was attributed to the partial segregation of metallic Cu to the catalyst surface, corroborated by XRD.Graphical abstractGraphical abstract for this articleProduction of biodiesel from the methanolysis of Simarouba Glauca DC oil via heterogeneous catalysis using ZnCuAl hydrotalcite type catalysts.
       
  • Tantalum vs Niobium MCF nanocatalysts in the green synthesis of
           chromene derivatives
    • Abstract: Publication date: Available online 19 June 2018Source: Catalysis TodayAuthor(s): Agata Smuszkiewicz, Jesús López-Sanz, Izabela Sobczak, Rosa M. Martín-Aranda, Maria Ziolek, Elena Pérez-MayoralTaMCF silicas modified with alkaline metals can be considered a novel family of highly efficient bifunctional catalysts involved in the synthesis of chromene derivatives, from salicylaldehyde 2 and acetonitrile compounds, under mild conditions, showing enhanced catalytic performance than their NbMCF analogues. The observed reactivity was mainly attributed to the higher basicity of the Me/TaMCF but also the texture of the samples. The Me/TaMCF silicas showed higher Brønsted basicity than the Nb ones as indicated by the stronger interaction between alkali metals and Ta in the UV–vis and the test reaction experiments.On the other hand, the basicity of Me/TaMCF together the reactivity degree and steric hindrance of the starting acetonitriles are key factors influencing the reaction selectivity. In conclusion, the basicity of the samples plays an important role initiating the reaction by activation of nucleophile but also a compromise between alkaline cation size and basicity is required.Graphical abstractGraphical abstract for this article
       
  • Oxygen Pathways in Oxidative Coupling of Methane and Related Processes.
           Case Study: NaWMn/SiO2 Catalyst
    • Abstract: Publication date: Available online 18 June 2018Source: Catalysis TodayAuthor(s): Mikhail Sinev, Ekaterina Ponomareva, Ilya Sinev, Vladimir Lomonosov, Yury Gordienko, Zukhra Fattakhova, Dmitry ShashkinThe chemical complexity of processes that accompany the oxygen turnover during the high-temperature selective oxidation processes, such as oxidative coupling of methane (OCM), oxidative dehydrogenation and oxidative cracking of light alkanes is analyzed. Particularly, chemical reactions and phase transitions in the complex oxide OCM catalyst NaWMn/SiO2 are studied using the X-ray photoelectron spectroscopy, X-ray powder diffraction, and scanning electron microscopy combined with local elemental analysis. It was found that during oxygen desorption crystalline Na2WO4 and Mn2O3 phases disappear, and newly-formed compounds solidify in the form of crystalline MnWO4 and the glue-like matter. The latter contains sodium and most likely Mn2+ ions. Its localization on the grain boundaries of the SiO2 (α-cristobalite) bulbs and morphology indicate that this matter is amorphous and has a high adhesion to the silica surface. After re-oxidation, the phase composition of the sample restores, although the size and location of the restored Na2WO4 and Mn2O3 particles evidence for their formation from the glue-like matter or its molten precursor. It was concluded that the supported components are present during the oxygen turnover in a molten state, in which all chemical and mass-transfer processes are accelerated.Graphical abstractGraphical abstract for this article
       
 
 
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