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  Subjects -> MATHEMATICS (Total: 864 journals)
    - APPLIED MATHEMATICS (69 journals)
    - GEOMETRY AND TOPOLOGY (19 journals)
    - MATHEMATICS (642 journals)
    - MATHEMATICS (GENERAL) (40 journals)
    - NUMERICAL ANALYSIS (19 journals)
    - PROBABILITIES AND MATH STATISTICS (75 journals)

MATHEMATICS (642 journals)                  1 2 3 4 | Last

Showing 1 - 200 of 538 Journals sorted alphabetically
Abakós     Open Access   (Followers: 4)
Abhandlungen aus dem Mathematischen Seminar der Universitat Hamburg     Hybrid Journal   (Followers: 2)
Academic Voices : A Multidisciplinary Journal     Open Access   (Followers: 2)
Accounting Perspectives     Full-text available via subscription   (Followers: 6)
ACM Transactions on Algorithms (TALG)     Hybrid Journal   (Followers: 16)
ACM Transactions on Computational Logic (TOCL)     Hybrid Journal   (Followers: 4)
ACM Transactions on Mathematical Software (TOMS)     Hybrid Journal   (Followers: 6)
ACS Applied Materials & Interfaces     Full-text available via subscription   (Followers: 21)
Acta Applicandae Mathematicae     Hybrid Journal   (Followers: 1)
Acta Mathematica     Hybrid Journal   (Followers: 10)
Acta Mathematica Hungarica     Hybrid Journal   (Followers: 2)
Acta Mathematica Scientia     Full-text available via subscription   (Followers: 5)
Acta Mathematica Sinica, English Series     Hybrid Journal   (Followers: 5)
Acta Mathematica Vietnamica     Hybrid Journal  
Acta Mathematicae Applicatae Sinica, English Series     Hybrid Journal  
Advanced Science Letters     Full-text available via subscription   (Followers: 5)
Advances in Applied Clifford Algebras     Hybrid Journal   (Followers: 3)
Advances in Calculus of Variations     Hybrid Journal   (Followers: 2)
Advances in Catalysis     Full-text available via subscription   (Followers: 5)
Advances in Complex Systems     Hybrid Journal   (Followers: 7)
Advances in Computational Mathematics     Hybrid Journal   (Followers: 15)
Advances in Decision Sciences     Open Access   (Followers: 4)
Advances in Difference Equations     Open Access   (Followers: 1)
Advances in Fixed Point Theory     Open Access   (Followers: 5)
Advances in Geosciences (ADGEO)     Open Access   (Followers: 9)
Advances in Linear Algebra & Matrix Theory     Open Access   (Followers: 1)
Advances in Materials Sciences     Open Access   (Followers: 16)
Advances in Mathematical Physics     Open Access   (Followers: 6)
Advances in Mathematics     Full-text available via subscription   (Followers: 10)
Advances in Numerical Analysis     Open Access   (Followers: 3)
Advances in Operations Research     Open Access   (Followers: 11)
Advances in Porous Media     Full-text available via subscription   (Followers: 4)
Advances in Pure and Applied Mathematics     Hybrid Journal   (Followers: 5)
Advances in Pure Mathematics     Open Access   (Followers: 4)
Advances in Science and Research (ASR)     Open Access   (Followers: 6)
Aequationes Mathematicae     Hybrid Journal   (Followers: 2)
African Journal of Educational Studies in Mathematics and Sciences     Full-text available via subscription   (Followers: 5)
African Journal of Mathematics and Computer Science Research     Open Access   (Followers: 4)
Afrika Matematika     Hybrid Journal   (Followers: 1)
Air, Soil & Water Research     Open Access   (Followers: 7)
AKSIOMA Journal of Mathematics Education     Open Access   (Followers: 1)
Algebra and Logic     Hybrid Journal   (Followers: 2)
Algebra Colloquium     Hybrid Journal   (Followers: 4)
Algebra Universalis     Hybrid Journal   (Followers: 2)
Algorithmic Operations Research     Full-text available via subscription   (Followers: 5)
Algorithms     Open Access   (Followers: 9)
Algorithms Research     Open Access   (Followers: 1)
American Journal of Biostatistics     Open Access   (Followers: 9)
American Journal of Computational and Applied Mathematics     Open Access   (Followers: 3)
American Journal of Mathematical Analysis     Open Access  
American Journal of Mathematics     Full-text available via subscription   (Followers: 7)
American Journal of Operations Research     Open Access   (Followers: 5)
American Mathematical Monthly     Full-text available via subscription   (Followers: 6)
An International Journal of Optimization and Control: Theories & Applications     Open Access   (Followers: 7)
Analele Universitatii Ovidius Constanta - Seria Matematica     Open Access   (Followers: 1)
Analysis     Hybrid Journal   (Followers: 2)
Analysis and Applications     Hybrid Journal   (Followers: 1)
Analysis and Mathematical Physics     Hybrid Journal   (Followers: 4)
Analysis Mathematica     Full-text available via subscription  
Annales Mathematicae Silesianae     Open Access  
Annales mathématiques du Québec     Hybrid Journal   (Followers: 4)
Annales UMCS, Mathematica     Open Access   (Followers: 1)
Annales Universitatis Paedagogicae Cracoviensis. Studia Mathematica     Open Access  
Annali di Matematica Pura ed Applicata     Hybrid Journal   (Followers: 1)
Annals of Combinatorics     Hybrid Journal   (Followers: 3)
Annals of Data Science     Hybrid Journal   (Followers: 8)
Annals of Discrete Mathematics     Full-text available via subscription   (Followers: 6)
Annals of Mathematics     Full-text available via subscription  
Annals of Mathematics and Artificial Intelligence     Hybrid Journal   (Followers: 6)
Annals of Pure and Applied Logic     Open Access   (Followers: 2)
Annals of the Alexandru Ioan Cuza University - Mathematics     Open Access  
Annals of the Institute of Statistical Mathematics     Hybrid Journal   (Followers: 1)
Annals of West University of Timisoara - Mathematics     Open Access  
Annuaire du Collège de France     Open Access   (Followers: 5)
Applicable Algebra in Engineering, Communication and Computing     Hybrid Journal   (Followers: 2)
Applications of Mathematics     Hybrid Journal   (Followers: 1)
Applied Categorical Structures     Hybrid Journal   (Followers: 2)
Applied Computational Intelligence and Soft Computing     Open Access   (Followers: 12)
Applied Mathematics     Open Access   (Followers: 3)
Applied Mathematics     Open Access   (Followers: 4)
Applied Mathematics & Optimization     Hybrid Journal   (Followers: 4)
Applied Mathematics - A Journal of Chinese Universities     Hybrid Journal  
Applied Mathematics Letters     Full-text available via subscription   (Followers: 1)
Applied Mathematics Research eXpress     Hybrid Journal   (Followers: 1)
Applied Numerical Mathematics     Hybrid Journal   (Followers: 5)
Applied Spatial Analysis and Policy     Hybrid Journal   (Followers: 4)
Arab Journal of Mathematical Sciences     Open Access   (Followers: 2)
Arabian Journal of Mathematics     Open Access   (Followers: 2)
Archive for Mathematical Logic     Hybrid Journal   (Followers: 1)
Archive of Applied Mechanics     Hybrid Journal   (Followers: 4)
Archive of Numerical Software     Open Access  
Archives of Computational Methods in Engineering     Hybrid Journal   (Followers: 4)
Arkiv för Matematik     Hybrid Journal   (Followers: 1)
Arnold Mathematical Journal     Hybrid Journal   (Followers: 1)
Artificial Satellites : The Journal of Space Research Centre of Polish Academy of Sciences     Open Access   (Followers: 17)
Asia-Pacific Journal of Operational Research     Hybrid Journal   (Followers: 3)
Asian Journal of Algebra     Open Access   (Followers: 1)
Asian Journal of Current Engineering & Maths     Open Access  
Asian-European Journal of Mathematics     Hybrid Journal   (Followers: 2)
Australian Mathematics Teacher, The     Full-text available via subscription   (Followers: 7)
Australian Primary Mathematics Classroom     Full-text available via subscription   (Followers: 2)
Australian Senior Mathematics Journal     Full-text available via subscription   (Followers: 1)
Automatic Documentation and Mathematical Linguistics     Hybrid Journal   (Followers: 5)
Axioms     Open Access  
Baltic International Yearbook of Cognition, Logic and Communication     Open Access  
Basin Research     Hybrid Journal   (Followers: 3)
BIBECHANA     Open Access  
BIT Numerical Mathematics     Hybrid Journal  
BoEM - Boletim online de Educação Matemática     Open Access  
Boletim Cearense de Educação e História da Matemática     Open Access  
Boletim de Educação Matemática     Open Access  
Boletín de la Sociedad Matemática Mexicana     Hybrid Journal  
Bollettino dell'Unione Matematica Italiana     Full-text available via subscription   (Followers: 1)
British Journal of Mathematical and Statistical Psychology     Full-text available via subscription   (Followers: 19)
Bruno Pini Mathematical Analysis Seminar     Open Access  
Buletinul Academiei de Stiinte a Republicii Moldova. Matematica     Open Access   (Followers: 6)
Bulletin des Sciences Mathamatiques     Full-text available via subscription   (Followers: 4)
Bulletin of Dnipropetrovsk University. Series : Communications in Mathematical Modeling and Differential Equations Theory     Open Access   (Followers: 1)
Bulletin of Mathematical Sciences     Open Access   (Followers: 2)
Bulletin of the Brazilian Mathematical Society, New Series     Hybrid Journal  
Bulletin of the London Mathematical Society     Hybrid Journal   (Followers: 3)
Bulletin of the Malaysian Mathematical Sciences Society     Hybrid Journal  
Calculus of Variations and Partial Differential Equations     Hybrid Journal  
Canadian Journal of Science, Mathematics and Technology Education     Hybrid Journal   (Followers: 18)
Carpathian Mathematical Publications     Open Access   (Followers: 1)
Catalysis in Industry     Hybrid Journal   (Followers: 1)
CEAS Space Journal     Hybrid Journal  
CHANCE     Hybrid Journal   (Followers: 5)
Chaos, Solitons & Fractals     Hybrid Journal   (Followers: 3)
ChemSusChem     Hybrid Journal   (Followers: 7)
Chinese Annals of Mathematics, Series B     Hybrid Journal  
Chinese Journal of Catalysis     Full-text available via subscription   (Followers: 2)
Chinese Journal of Mathematics     Open Access  
Clean Air Journal     Full-text available via subscription   (Followers: 2)
Cogent Mathematics     Open Access   (Followers: 2)
Cognitive Computation     Hybrid Journal   (Followers: 4)
Collectanea Mathematica     Hybrid Journal  
College Mathematics Journal     Full-text available via subscription   (Followers: 1)
COMBINATORICA     Hybrid Journal  
Combustion Theory and Modelling     Hybrid Journal   (Followers: 13)
Commentarii Mathematici Helvetici     Hybrid Journal   (Followers: 1)
Communications in Contemporary Mathematics     Hybrid Journal  
Communications in Mathematical Physics     Hybrid Journal   (Followers: 1)
Communications On Pure & Applied Mathematics     Hybrid Journal   (Followers: 3)
Complex Analysis and its Synergies     Open Access   (Followers: 2)
Complex Variables and Elliptic Equations: An International Journal     Hybrid Journal  
Complexus     Full-text available via subscription  
Composite Materials Series     Full-text available via subscription   (Followers: 9)
Comptes Rendus Mathematique     Full-text available via subscription   (Followers: 1)
Computational and Applied Mathematics     Hybrid Journal   (Followers: 2)
Computational and Mathematical Methods in Medicine     Open Access   (Followers: 2)
Computational and Mathematical Organization Theory     Hybrid Journal   (Followers: 2)
Computational Complexity     Hybrid Journal   (Followers: 4)
Computational Mathematics and Modeling     Hybrid Journal   (Followers: 8)
Computational Mechanics     Hybrid Journal   (Followers: 4)
Computational Methods and Function Theory     Hybrid Journal  
Computational Optimization and Applications     Hybrid Journal   (Followers: 7)
Computers & Mathematics with Applications     Full-text available via subscription   (Followers: 5)
Concrete Operators     Open Access   (Followers: 4)
Confluentes Mathematici     Hybrid Journal  
COSMOS     Hybrid Journal  
Cryptography and Communications     Hybrid Journal   (Followers: 12)
Cuadernos de Investigación y Formación en Educación Matemática     Open Access  
Cubo. A Mathematical Journal     Open Access  
Czechoslovak Mathematical Journal     Hybrid Journal   (Followers: 1)
Demographic Research     Open Access   (Followers: 11)
Demonstratio Mathematica     Open Access  
Dependence Modeling     Open Access  
Design Journal : An International Journal for All Aspects of Design     Hybrid Journal   (Followers: 28)
Developments in Clay Science     Full-text available via subscription   (Followers: 1)
Developments in Mineral Processing     Full-text available via subscription   (Followers: 3)
Dhaka University Journal of Science     Open Access  
Differential Equations and Dynamical Systems     Hybrid Journal   (Followers: 2)
Discrete Mathematics     Hybrid Journal   (Followers: 7)
Discrete Mathematics & Theoretical Computer Science     Open Access  
Discrete Mathematics, Algorithms and Applications     Hybrid Journal   (Followers: 2)
Discussiones Mathematicae Graph Theory     Open Access   (Followers: 1)
Doklady Mathematics     Hybrid Journal  
Duke Mathematical Journal     Full-text available via subscription   (Followers: 1)
Edited Series on Advances in Nonlinear Science and Complexity     Full-text available via subscription  
Electronic Journal of Graph Theory and Applications     Open Access   (Followers: 2)
Electronic Notes in Discrete Mathematics     Full-text available via subscription   (Followers: 2)
Elemente der Mathematik     Full-text available via subscription   (Followers: 3)
Energy for Sustainable Development     Hybrid Journal   (Followers: 9)
Enseñanza de las Ciencias : Revista de Investigación y Experiencias Didácticas     Open Access  
Ensino da Matemática em Debate     Open Access  
Entropy     Open Access   (Followers: 4)
ESAIM: Control Optimisation and Calculus of Variations     Full-text available via subscription   (Followers: 1)
European Journal of Combinatorics     Full-text available via subscription   (Followers: 4)
European Journal of Mathematics     Hybrid Journal   (Followers: 1)
European Scientific Journal     Open Access   (Followers: 2)
Experimental Mathematics     Hybrid Journal   (Followers: 3)
Expositiones Mathematicae     Hybrid Journal   (Followers: 2)
Facta Universitatis, Series : Mathematics and Informatics     Open Access  
Fasciculi Mathematici     Open Access  
Finite Fields and Their Applications     Full-text available via subscription   (Followers: 4)
Fixed Point Theory and Applications     Open Access   (Followers: 1)
Formalized Mathematics     Open Access   (Followers: 2)
Foundations and Trends® in Econometrics     Full-text available via subscription   (Followers: 4)
Foundations and Trends® in Networking     Full-text available via subscription   (Followers: 1)

        1 2 3 4 | Last

Journal Cover Chinese Journal of Catalysis
  [SJR: 0.6]   [H-I: 29]   [2 followers]  Follow
    
   Full-text available via subscription Subscription journal  (Not entitled to full-text)
   ISSN (Print) 1872-2067
   Published by Elsevier Homepage  [3030 journals]
  • Engineering vacancies for solar photocatalytic applications
    • Abstract: Publication date: April 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 4
      Author(s): Mingce Long, Longhui Zheng
      In contrast to the exploration of novel photocatalytic materials, vacancy engineering of traditional photocatalysts comprising earth-abundant elements represents an effective method for enhancing photocatalytic performance without introducing alien elements. This minireview analyzes the latest progress in engineering vacancies in photocatalysts, remarks on state-of-the-art characterization techniques for vacancies, and reviews the formation chemistry and fundamental benefits of anion and cation vacancies in typical photocatalysts. Although knowledge of these vacancies is increasing, challenges remain in this field, and possible further research is therefore also discussed.
      Graphical abstract image

      PubDate: 2017-04-24T03:30:11Z
       
  • Selective aerobic oxidation promoted by highly efficient multi-nitroxy
           organocatalysts
    • Abstract: Publication date: April 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 4
      Author(s): Kexian Chen, Haiying Xie
      Selective oxidation with molecular oxygen as the sole oxidant under mild conditions is of crucial importance for the long-term sustainable exploitation of available feedstocks and the formation of required intermediates for organic synthesis and industrial processes. Among the developed oxidation protocols, innovative strategies using hydroxyimide organocatalysts in combination with metallic or metal-free cocatalysts have attracted much attention because of the good activities and selectivities of such catalysts in the oxo functionalization of hydrocarbons. This method is based on the reaction using N-hydroxyphthalimide, which was first reported by Ishii's group in the 1990s. Although the important and wide-ranging applications of such catalysts have been summarized recently, there are no reviews that focus solely on oxidation strategies using multi-nitroxy organocatalysts, which have interesting properties and high reactivities. This review covers the concise synthetic methods and mechanistic profiles of known multi-nitroxy organocatalysts and summarizes significant advances in their use in efficient aerobic oxidation. Based on a combination of experimental and theoretical results, guidelines for the future rational design of multi-nitroxy organocatalysts are proposed, and the properties of various model multi-nitroxy organocatalysts are predicted. The present overview of the advantages, limitations, and potential applications of multi-nitroxy organocatalysts can provide useful tools for researchers in the field of selective oxidation.
      Graphical abstract image

      PubDate: 2017-04-24T03:30:11Z
       
  • Supercritical synthesis of platinum-modified titanium dioxide for solar
           fuel production from carbon dioxide
    • Abstract: Publication date: April 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 4
      Author(s): Susana Tostón, Rafael Camarillo, Fabiola Martínez, Carlos Jiménez, Jesusa Rincón
      This paper investigates the properties of TiO2-based photocatalysts synthesised under supercritical conditions. Specifically, the characteristics of Pt dispersed on TiO2 catalysts obtained in supercritical CO2 are discussed and compared with those of commercial TiO2. The photocatalytic activity of the synthesised catalysts in the CO2 photoreduction reaction to produce solar fuel is tested. The main conclusion of the study is that photocatalysts with better or similar features, including high surface area, crystallisation degree, hydroxyl surface concentration, pore volume, absorbance in the visible range and methane production rate, to those of commercial TiO2 may be produced for the reduction of CO2 to fuel by synthesis in supercritical media.
      Graphical abstract image

      PubDate: 2017-04-24T03:30:11Z
       
  • Simple synthesis of sub-nanometer Pd clusters: High catalytic activity of
           Pd/PEG-PNIPAM in Suzuki reaction
    • Abstract: Publication date: April 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 4
      Author(s): Zhe Chen, Yu Liang, Da-Shuang Jia, Zhi-Min Cui, Wei-Guo Song
      Ultra-small metal nanoclusters have high surface energy and abundant active sites, and therefore their catalytic activities are usually significantly higher than those of larger nanoparticles. A temperature-responsive copolymer, namely poly(ethylene glycol)-co-poly(N-isopropylacrylamide) (PEG-PNIPAM) was synthesized as the first step, and then ultra-small Pd clusters stabilized within PEG-PNIPAM copolymer micelles were formed by direct reduction. Pd nanoclusters of size less than 2 nm showed outstanding catalytic activity in the Suzuki coupling reaction. The reaction between iodobenzene and phenylboronic acid was completed in as little as 10 s (turnover frequency = 4.3 × 104 h−1). A yield of 64% was achieved in 5 min in the reaction between chlorobenzene and phenylboronic acid. The catalyst showed significant deactivation during three consecutive runs. However, this composite catalyst consisting of Pd/PEG-PNIPAM can be easily recycled based on the reversible phase transition of temperature-responsive PEG-PNIPAM. This catalyst therefore has good potential for practical applications.
      Graphical abstract image

      PubDate: 2017-04-24T03:30:11Z
       
  • Cu2O/SiC as efficient catalyst for Ullmann coupling of phenols with aryl
           halides
    • Abstract: Publication date: April 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 4
      Author(s): Yibing Wang, Xiaoning Guo, Manqian Lü, Zhaoyang Zhai, Yingyong Wang, Xiangyun Guo
      A Cu2O/SiC heterogeneous catalyst was prepared via a two-step liquid-phase method using diethylene glycol as both the solvent and the reducing agent. The catalyst was characterized using X-ray diffraction, X-ray photoelectron spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM), and H2 temperature-programmed reduction. All the results indicate that Cu is present on the SiC support primarily as Cu2O. The SEM and TEM results show that cubic Cu2O nanoparticles are uniformly dispersed on the β-SiC surface. The reaction conditions, namely the temperature, reaction time, and amounts of base and catalyst used, for the Ullmann-type C–O cross-coupling reaction were optimized. A model reaction was performed using iodobenzene (14.0 mmol) and phenol (14.0 mmol) with Cu2O/SiC (5 wt% Cu) as the catalyst, Cs2CO3 (1.0 equiv.) as the base, and tetrahydrofuran as the solvent at 150 °C for 3 h; a yield of 97% was obtained and the turnover frequency (TOF) was 1136 h−1. The Cu2O/SiC catalyst has a broad substrate scope and can be used in Ullmann-type C–O cross-coupling reactions of aryl halides and phenols bearing a variety of different substituents. The catalyst also showed high activity in the Ullmann-type C–S cross-coupling of thiophenol with iodobenzene and substituted iodobenzenes; a TOF of 1186 h−1 was achieved. The recyclability of the Cu2O/SiC catalyst in the O-arylation of phenol with iodobenzene was investigated under the optimum conditions. The yield decreased from 97% to 64% after five cycles. The main reason for the decrease in the catalyst activity is loss of the active component, i.e., Cu2O.
      Graphical abstract image

      PubDate: 2017-04-24T03:30:11Z
       
  • Purification and characterization of alkaline chitinase from Paenibacillus
           pasadenensis CS0611
    • Abstract: Publication date: April 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 4
      Author(s): Xiaoxiao Guo, Pei Xu, Minhua Zong, Wenyong Lou
      An extracellular chitinase produced by Paenibacillus pasadenensis CS0611 was purified by ammonium sulfate precipitation, HiTrap DEAE FF and HiLoad 26/600 Superdex 200pg column chromatography. The apparent molecular mass determined by sodium dodecyl sulfate polyacrylamide gel electrophoresis was 69 kDa. The optimum pH and optimum temperature of the chitinase were 5.0 and 50 °C, respectively. The enzyme showed high stability at alkaline pH values and temperatures below 40 °C. Additionally, the metal ions Mn2+, Mg2+, and Co2+ inhibited activity of the chitinase. The chitinase was active on colloidal chitin with an apparent K m of 4.41 mg/mL and V max of 1.08 mg/min. Substrate spectrum analysis indicated that the chitinase reacted preferentially with the glucosidic bond between GlcNAc-GlcNAc. The enzymatic hydrolysate was analyzed by high-performance liquid chromatography and thin layer chromatography, and clearly showed that a subunit of (GlcNAc)2 was the main hydrolysis product.
      Graphical abstract image

      PubDate: 2017-04-24T03:30:11Z
       
  • Fe, N, S-doped porous carbon as oxygen reduction reaction catalyst in
           acidic medium with high activity and durability synthesized using CaCl2 as
           template
    • Abstract: Publication date: April 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 4
      Author(s): Chi Chen, Zhiyou Zhou, Yucheng Wang, Xue Zhang, Xiaodong Yang, Xinsheng Zhang, Shigang Sun
      Proton exchange membrane fuel cells suffer from the sluggish kinetics of the oxygen reduction reaction (ORR) and the high cost of Pt catalysts. In the present work, a high-performance ORR catalyst based on Fe, N, S-doped porous carbon (FeNS-PC) was synthesized using melamine formaldehyde resin as C and N precursors, Fe(SCN)3 as Fe and S precursors, and CaCl2 as a template via a two-step heat treatment without a harsh template removal step. The results show that the catalyst treated at 900 °C (FeNS-PC-900) had a high surface area of 775 m2/g, a high mass activity of 10.2 A/g in an acidic medium, and excellent durability; the half-wave potential decreased by only 20 mV after 10000 potential cycles. The FeNS-PC-900 catalyst was used as the cathode in a proton exchange membrane fuel cell and delivered a peak power density of 0.49 W/cm2. FeNS-PC-900 therefore has good potential for use in practical applications.
      Graphical abstract image

      PubDate: 2017-04-24T03:30:11Z
       
  • Correlation between H-ZSM-5 crystal size and catalytic performance in the
           methanol-to-aromatics reaction
    • Abstract: Publication date: April 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 4
      Author(s): Lingzhi Yang, Zhiyuan Liu, Zhi Liu, Wenyong Peng, Yunqi Liu, Chenguang Liu
      The porosity of H-ZSM-5 zeolite is known to facilitate the diffusion of molecules in the methanol-to-aromatics (MTA) reaction. The activity and selectivity of the H-ZSM-5 catalyst in the MTA reaction has been studied as a function of crystal size. ZSM-5 zeolites with different crystal sizes were successfully synthesized by conventional hydrothermal methods. Tailoring ZSM-5 particle size was easily controlled by changes to the sol-gel composition, and in particular, the deionized water to tetrapropylammonium hydroxide ratio, and crystallization time. The structure of the H-ZSM-5 zeolites were characterized by X-ray diffraction and the morphology of the zeolite particles was determined by scanning electron microscopy. N2 adsorption-desorption measurements established changes to the textural properties, and compositional properties were characterized by X-ray fluorescence spectroscopy. Acidity measurements of the catalysts were measured by pyridine-adsorbed Fourier transform infrared spectroscopy and the temperature-programmed desorption of ammonia. After subjecting the catalysts to the MTA reaction, the total amount of coke formed on the spent deactivated catalysts was determined by thermal gravimetric analysis. The results show that the SiO2/Al2O3 molar ratios and acidic properties of the H-ZSM-5 samples are similar, however, the nano-sized hierarchical ZSM-5 zeolite with an additional level of auxiliary pores possesses a higher surface area, larger mesopore volume and larger macropore volume, resulting in more effective mass transportation properties. The H-ZSM-5 zeolite catalysts were evaluated for their activity towards the MTA reaction as a function of crystal size. The nano-sized H-ZSM-5 catalyst having shorter diffusion path lengths, substantial mesoporosity and a high external surface area showed excellent selectivity toward aromatics (average > 42%) and benzene, toluene and xylenes (37% at 180 min). Furthermore, lower coking levels were observed on the nano-sized H-ZSM-5 catalyst when compared with the H-ZSM-5 catalysts possessing larger particle sizes and is attributed to a reduction in polyaromatic hydrocarbons being deposited within the internal surface area.
      Graphical abstract image

      PubDate: 2017-04-24T03:30:11Z
       
  • Porous Rh/BINAP polymers as efficient heterogeneous catalysts for
           asymmetric hydroformylation of styrene: Enhanced enantioselectivity
           realized by flexible chiral nanopockets
    • Abstract: Publication date: April 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 4
      Author(s): Tao Wang, Wenlong Wang, Yuan Lyu, Kai Xiong, Cunyao Li, Hao Zhang, Zhuangping Zhan, Zheng Jiang, Yunjie Ding
      A new chiral monomer, (S)-5,5′-divinyl-BINAP, was successfully synthesized and embedded into two different porous organic polymers (Poly-1 and Poly-2). After loading a Rh species, the catalysts were applied for the heterogeneous asymmetric hydroformylation of styrene. Compared with the homogeneous BINAP analogue, the enantioselectivity of Rh/Poly-1 catalyst was drastically increased by approximately 70%. The improved enantioselectivity of the porous Rh/BINAP polymers was attributed to the presence of flexible chiral nanopockets resulting from the increased bulk of the R groups near the catalytic center.
      Graphical abstract image

      PubDate: 2017-04-24T03:30:11Z
       
  • Influence of supports for selective production of 2,5-dimethylfuran via
           
    • Abstract: Publication date: April 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 4
      Author(s): Sanjay Srivastava, G.C. Jadeja, Jigisha Parikh
      The hydrogenolysis of carbon–oxygen bonds is an important model reaction in upgrading biomass-derived furanic compounds to transportation fuels. One of these model reactions, namely conversion of 5-hydroxymethylfurfural (HMF) to the gasoline additive 2,5-dimethylfuran (DMF), is especially attractive. In this study, bimetallic Cu-Co catalysts supported on CeO2, ZrO2, and Al2O3 were used for the selective hydrogenolysis of HMF to DMF. The structures of the fresh and used catalysts were studied using X-ray diffraction, the Brunauer-Emmett-Teller method, transmission electron microscopy, temperature-programmed reduction by H2, temperature-programmed desorption of NH3, and CHNS analysis. The structures were correlated with the catalytic activities. The Cu-Co/CeO2 catalyst produced mainly 2,5-bis(hydroxymethyl)furan via reduction of C=O bonds on large Cu particles. The Cu-Co/Al2O3 catalyst gave the best selectivity for DMF, as a result of a combination of highly dispersed Cu, mixed copper–cobalt oxides, and suitable weak acidic sites. Cu-Co/ZrO2 had low selectivity for DMF and produced a combination of various over-hydrogenolysis products, including 2,5-dimethyltetrahydrofuran and 5,5-oxybis(methylene)-bis(2-methylfuran), because of the presence of strong acidic sites. The reaction pathways and effects of various operating parameters, namely temperature, H2 pressure, and time, were studied to enable optimization of the selective conversion of HMF to DMF over the Cu-Co/Al2O3 catalyst.
      Graphical abstract image

      PubDate: 2017-04-24T03:30:11Z
       
  • Synthesis, characterization and application of BiVO4 photoanode for
           photoelectrochemical oxidation of chlorate
    • Abstract: Publication date: April 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 4
      Author(s): Seyed Ghorban Hosseini, Saeid Safshekan
      A high-quality polycrystalline bismuth vanadate (BiVO4) film was prepared on a fluorine-doped tin oxide substrate via a facile two-step strategy involving electrodeposition and annealing processes. The morphology and structural characterization of the resulting film were investigated by different methods including scanning electron microscopy, transmission electron microscopy, X-ray diffraction (XRD), and Fourier transform infrared, ultraviolet-visible (UV-vis) absorption, and Raman spectroscopies. XRD patterns as well as optical measurements revealed that BiVO4 film crystallized with a pure monoclinic scheelite structure. The prepared BiVO4 film was used for heterogeneous oxidation of chlorate ions in aqueous solution via electrochemical (EC), photochemical (PC), and photoelectrochemical (PEC) processes. The decrease in concentration of chlorate was monitored using UV-vis absorption spectroscopy. The results revealed that BiVO4 could effectively perform chlorate oxidation under light irradiation through a PEC method. The kinetics of chlorate oxidation was consistent with a first-order reaction, and the rate constant for the PEC process was found to be much higher than those of EC and PC. Furthermore, a possible photocatalytic oxidation mechanism for chlorate mainly based on the formation of perchlorate ions is proposed.
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      PubDate: 2017-04-24T03:30:11Z
       
  • CO2 hydrogenation to methanol over Cu/Zn/Al/Zr catalysts prepared by
           liquid reduction
    • Abstract: Publication date: April 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 4
      Author(s): Xiaosu Dong, Feng Li, Ning Zhao, Yisheng Tan, Junwei Wang, Fukui Xiao
      Cu/Zn/Al/Zr catalysts containing Cu in three valence states (Cu2+, Cu+ and Cu0) were prepared using a liquid reduction method and subsequently calcined at different temperatures. The effects of the calcination temperature on the catalyst structure, interactions among components, reducibility and dispersion of Cu species, surface properties and exposed Cu surface area were systematically investigated. These materials were also applied to the synthesis of methanol via the hydrogenation of CO2. The results show that a large exposed Cu surface area promotes catalytic CO2 conversion and that there is a close correlation between the Cu+/Cu0 ratio and the selectivity for methanol. A calcination temperature of 573 K was found to produce a Cu/Zn/Al/Zr catalyst exhibiting the maximum activity during the synthesis of methanol.
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      PubDate: 2017-04-24T03:30:11Z
       
  • Ordered mesoporous Sn-SBA-15 as support for Pt catalyst with enhanced
           performance in propane dehydrogenation
    • Abstract: Publication date: April 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 4
      Author(s): Bing Li, Zhenxin Xu, Wei Chu, Shizhong Luo, Fangli Jing
      A series of Sn-incorporated SBA-15 materials with high specific surface areas and highly ordered mesoporous structures were synthesized by a facile one-pot method and used as catalyst supports. A reference sample was also prepared using a conventional impregnation method. The catalysts were characterized using various methods, and their activities in propane dehydrogenation were investigated. The incorporation of Sn into the SBA-15 matrix led to strong interactions between Sn species and the support, and these helped to maintain the oxidation states of Sn species during the reaction. Substitution with Sn changed the interfacial properties of the Pt species and improved the function and effect of the Sn promoter. The catalytic activities and stabilities of the Pt catalysts supported on Sn-incorporated SBA-15 were better than those of the impregnated sample. However, the catalytic performance deteriorated when an excessive amount of Sn was introduced and the interactions among Pt, Sn species, and the support became weaker. The Pt/0.5Sn-SBA-15 catalyst gave the best propene selectivity, i.e., 98.5%, with a corresponding propane conversion of about 43.8%.
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      PubDate: 2017-04-24T03:30:11Z
       
  • Transformation of carbon dioxide into valuable chemicals over bifunctional
           metallosalen catalysts bearing quaternary phosphonium salts
    • Abstract: Publication date: April 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 4
      Author(s): Wuying Zhang, Rongchang Luo, Qihang Xu, Yaju Chen, Xiaowei Lin, Xiantai Zhou, Hongbing Ji
      The chemical transformation of CO2 under mild conditions remains a great challenge because of its exceptional kinetic and thermodynamic stability. Two important reactions in the transformation of CO2 are the N-formylation reaction of amines using hydrosilanes and CO2, and the cycloaddition of CO2 to epoxides. Here, we report the high efficiency of bifunctional metallosalen complexes bearing quaternary phosphonium salts in catalyzing both of these reactions under solvent-free, mild conditions without the need for co-catalysts. The catalysts' bifunctionality is attributed to an intramolecular cooperative process between the metal center and the halogen anion. Depending on the reaction, this activates CO2 by permitting either the synergistic activation of Si–H bond via metal–hydrogen coordinative bond (M–H) or the dual activation of epoxide via metal–oxygen coordinative bond (M–O). The one-component catalysts are also shown to be easily recovered and reused five times without significant loss of activity or selectivity. The current results are combined with previous work in the area to propose the relevant reaction mechanisms.
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      PubDate: 2017-04-24T03:30:11Z
       
  • Nanoscale graphene oxide sheets as highly efficient carbocatalysts in
           green oxidation of benzylic alcohols and aromatic aldehydes
    • Abstract: Publication date: April 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 4
      Author(s): Alireza Sedrpoushan, Masoud Heidari, Omid Akhavan
      Nanoscale graphene oxide (NGO) sheets were synthesized and used as carbocatalysts for effective oxidation of benzylic alcohols and aromatic aldehydes. For oxidation of alcohols in the presence of H2O2 at 80 °C, the NGOs (20% mass fraction) as carbocatalysts showed selectivity toward aldehyde. The rate and yield of this reaction strongly depended on the nature of substituents on the alcohol. For 4-nitrobenzyl alcohol, <10% of it was converted into the corresponding carboxylic acid after 24 h. By contrast, 4-methoxybenzyl alcohol and diphenylmethanol were completely converted into the corresponding carboxylic acid and ketone after only 9 and 3 h, respectively. The conversion rates for oxidation of aromatic aldehydes by NGO carbocatalysts were higher than those for alcohol oxidation. For all the aldehydes, complete conversion to the corresponding carboxylic acids was achieved using 7% (mass fraction) of NGO at 70 °C within 2–3 h. Possible mechanisms for NGO carbocatalyst structure-dependent oxidation of benzyl alcohols and structure-independent oxidation of aromatic aldehydes are discussed.
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      PubDate: 2017-04-24T03:30:11Z
       
  • Zirconium triflate grafted on SBA-15 as a highly efficient solid acid
           catalyst for ring opening of epoxides by amines and alcohols
    • Abstract: Publication date: April 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 4
      Author(s): Kamlesh N. Tayade, Lianyue Wang, Sensen Shang, Wen Dai, Manish Mishra, Shuang Gao
      Metal (Al, Ti, Zr) triflate grafted mesoporous SBA-15 (AlTf/S, TiTf/S, ZrTf/S) samples were synthesized as inexpensive solid acid materials by a simple one-pot-two-step synthesis methodology. These materials were characterized by X-ray diffraction, N2-sorption, thermogravimetric analysis, Fourier transform infrared spectroscopy (FT-IR), in-situ pyridine FT-IR spectroscopy, and elemental analysis. ZrTf/S was found to be a highly efficient and reusable solid acid catalyst for ring opening of epoxides with amines and alcohols and produced β-amino alcohols and β-alkoxy alcohols respectively under ambient reaction conditions. The ZrTf/S catalyst showed the highest activity, which was attributed to its high acidity compared with that of the Ti and Al containing samples.
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      PubDate: 2017-04-24T03:30:11Z
       
  • Preface to Special Column on Novel Catalysts for Energy and Environmental
           Issues
    • Abstract: Publication date: March 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 3
      Author(s): Atsushi Fukuoka


      PubDate: 2017-04-10T02:08:53Z
       
  • Conversion of glycerol to acrolein by mesoporous sulfated zirconia-silica
           catalyst
    • Abstract: Publication date: March 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 3
      Author(s): Hirokazu Kobayashi, Shogo Ito, Kenji Hara, Atsushi Fukuoka
      A mesoporous sulfated zirconia-silica catalyst bearing only Brønsted acid sites converted glycerol to acrolein in 81% yield with 82% selectivity. Space time yield as high as 9.0 mmol h−1 gcat −1 was achieved even at a low reaction temperature of 523 K. The catalytic activity and selectivity were higher than those of typical sulfated zirconia. It is proposed that the milder acidity due to dilution of zirconium species by silica and large pore size for faster diffusion contributed towards the better catalytic performance.
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      PubDate: 2017-04-10T02:08:53Z
       
  • Preparation of Sn-β-zeolite via immobilization of Sn/choline chloride
           complex for glucose-fructose isomerization reaction
    • Abstract: Publication date: March 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 3
      Author(s): Asep Bayu, Surachai Karnjanakom, Katsuki Kusakabe, Abuliti Abudula, Guoqing Guan
      Well dispersion of tin species in an isolated form is a quite challenge since tin salts are easily hydrolyzed into (hydr)oxides during aqueous stannation of β-zeolite. In this study, immobilization of tin species on high silica commercial β-zeolite by using SnCl2/Choline chloride (ChCl) complex followed with calcination provided a convenient way to get well dispersed Sn in β-zeolite in the aqueous condition, which was observed based on electron microscopy images, UV visible spectra and X-ray diffraction pattern. The existence of ChCl facilitated tin species to incorporate into zeolite. (1−2) wt% of Sn loaded β-zeolites exhibited good catalytic activity and high selectivity for glucose-fructose isomerization reaction.
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      PubDate: 2017-04-10T02:08:53Z
       
  • Reductive transformation of CO2: Fluoride-catalyzed reactions with waste
           silicon-based reducing agents
    • Abstract: Publication date: March 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 3
      Author(s): Ken Motokura, Masaki Naijo, Sho Yamaguchi, Akimitsu Miyaji, Toshihide Baba
      CO2 is one of the most important “renewable” carbon sources. To transform CO2 to useful organic compounds, we examined the reactivity of two model silicon-based “waste” materials, disilanes and metallic Si powder, as reducing agents. In these reactions, fluoride salts were found to be active catalysts: CO2 was converted to formic acid at atmospheric pressure in the presence of H2O as a proton source and the silicon-based reducing reagents. Based on in-situ NMR and kinetics analyses, a hydrosilane and penta-coordinate Si species are proposed as the reaction intermediate and active species, respectively.
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      PubDate: 2017-04-10T02:08:53Z
       
  • Photocatalytic aerobic oxidation of toluene and its derivatives to
           aldehydes on Pd/Bi2WO6
    • Abstract: Publication date: March 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 3
      Author(s): Bo Yuan, Bao Zhang, Zhiliang Wang, Shengmei Lu, Jun Li, Yan Liu, Can Li
      The selective oxidation of toluene and its derivatives is extremely important in the chemical industry. The use of photocatalysis in organic synthesis has attracted considerable attention among synthetic chemists because of its “green” environmental characteristics. In this study, nanoscale Bi2WO6 with a flower-like morphology was found to be a highly efficient photocatalyst in the catalytic oxidation of toluene and its derivatives using O2 as the oxidant. The loading of Pd nanoparticles as a cocatalyst onto the flower-like Bi2WO6 was found to produce a significant enhancement in the catalytic activity. Mechanistic investigation showed that the superior performance of Pd/Bi2WO6 could be attributed to the improvement of both the reductive and oxidative abilities of Bi2WO6 by the loading of the cocatalyst.
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      PubDate: 2017-04-10T02:08:53Z
       
  • Preparation and characterization of ternary magnetic g-C3N4 composite
           photocatalysts for removal of tetracycline under visible light
    • Abstract: Publication date: March 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 3
      Author(s): Xu Tang, Liang Ni, Juan Han, Yun Wang
      A stable PNIPAM/Fe3O4/g-C3N4 composite photocatalyst was designed and prepared by a thermal photoinitiation technology. The structure and properties of the materials were characterized and the composite photocatalyst was found to show good stability for tetracycline degradation. The sample not only retained the magnetic properties of Fe3O4, allowing it to be recycled, but its photocatalytic properties could also be changed by controlling the temperature of the reaction system. The degradation intermediate products of tetracycline were further investigated by MS. This work provides a new facile strategy for the development of intelligent and recyclable photocatalytic materials.
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      PubDate: 2017-04-10T02:08:53Z
       
  • Synthesis and characterization of PMoV/Fe3O4/g-C3N4 from melamine: An
           industrial green nanocatalyst for deep oxidative desulfurization
    • Abstract: Publication date: March 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 3
      Author(s): Ezzat Rafiee, Maryam Khodayari
      A facile approach to the preparation of a novel magnetically separable H5PMo10V2O40/Fe3O4/g-C3N4 (PMoV/Fe3O4/g-C3N4) nanocomposite by chemical impregnation is demonstrated. The prepared nanocomposite was characterized and its acidity was measured by potentiometric titration. PMoV/Fe3O4/g-C3N4 showed high catalytic activity in the selective oxidative desulfurization of sulfides to their corresponding sulfoxides or sulfones. The catalytic oxidation of a dibenzothiophene (DBT)-containing model oil and that of real oil were also studied under optimized conditions. In addition, the effects of various nitrogen compounds, as well as the use of one- and two-ring aromatic hydrocarbons as co-solvents, on the catalytic removal of sulfur from DBT were investigated. The catalyst was easily separated and could be recovered from the reaction mixture by using an external magnetic field. Additionally, the remaining reactants could be separated from the products by simple decantation if an appropriate solvent was chosen for the extraction. The advantages of this nanocatalyst are its high catalytic activity and reusability; it can be used at least four times without considerable loss of activity.
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      PubDate: 2017-04-10T02:08:53Z
       
  • Synthesis of biaryls using palladium nanoparticles immobilized on peptide
           nanofibers as catalyst and hydroxybenzotriazole as novel phenylating
           reagent
    • Abstract: Publication date: March 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 3
      Author(s): Arash Ghorbani-Choghamarani, Zahra Taherinia
      Peptide nanofibers decorated with palladium nanoparticles catalyzed direct coupling of aryl halides with hydroxybenzotriazole to afford the corresponding biaryls in good to excellent yields. The coupling reactions proceeded under simple, green, and mild conditions. The peptide nanofibers were used as recyclable supports in the coupling reactions. This approach is the first to use hydroxybenzotriazole as a phenylating agent.
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      PubDate: 2017-04-10T02:08:53Z
       
  • Pt-CeO2/SiO2 catalyst for CO oxidation in humid air at ambient temperature
    • Abstract: Publication date: March 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 3
      Author(s): Shirish S. Punde, Bruce J. Tatarchuk
      CO self-poisoning and slow surface kinetics pose major challenges to a CO oxidation catalyst that should work at ambient temperature. Furthermore, the presence of moisture would cause passivation of the catalyst. A highly active ceria promoted Pt catalyst (4%Pt-12%CeO2/SiO2; conversion ≥ 99% at low (< 500 ppm) and high (> 2500 ppm) CO concentrations was developed for CO oxidation at ambient temperature in humid air. Catalyst preparation variables such as Pt and CeO2 loading, ceria deposition method, drying and calcination conditions for the ceria and Pt precursors were optimized experimentally. The activity was correlated with surface properties using CO/H2 chemisorption, O2-H2 titration, X-ray diffraction and BET surface area analysis. The method of CeO2 deposition had a significant impact on the catalytic activity. CeO2 deposition by impregnation resulted in a catalyst that was three times more active than that prepared by deposition precipitation or CeO2 grafting. O2-H2 titration results revealed that the close association of ceria and Pt in the case of CeO2 deposition by impregnation resulted in higher activity. The catalyst support used was also crucial as a silica supported catalyst was five times more active than an alumina supported catalyst. The particle size and pore structure of the catalyst support were also crucial as the reaction was diffusion controlled. The drying and calcination conditions of the ceria and Pt precursors also played a crucial role in determining the catalytic activity. The Pt-CeO2/SiO2 catalysts with Pt > 2.5 wt% and CeO2 > 15 wt% were highly active (TOF > 0.02 s−1) and stable (conversion ≥ 99% after 15 h) at ambient conditions.
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      PubDate: 2017-04-10T02:08:53Z
       
  • Surface treatment effect on the photocatalytic hydrogen generation of
           CdS/ZnS core-shell microstructures
    • Abstract: Publication date: March 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 3
      Author(s): Jinzhan Su, Tao Zhang, Lu Wang, Jinwen Shi, Yubin Chen
      CdS/ZnS core-shell microparticles were prepared by a simple two-step method combining ultrasonic spray pyrolysis and chemical bath deposition. The core-shell structures showed enhanced photocatalytic properties compared with those of CdS or ZnS spherical particles. CdS/ZnS photocatalysts with different amount of ZnS loaded as shells were prepared by adjusting the concentrations of Zn and S precursors during synthesis. The optical properties and photocatalytic activity for hydrogen production were investigated and the amount of ZnS loaded as shell was optimized. Thermal annealing and hydrothermal sulfurization treatments were applied to the core-shell structure and both treatments enhanced the material's photocatalytic activity and stability by eliminating crystalline defects and surface states. The result showed that thermal annealing treatment improved the bulk crystallinity and hydrothermal sulfurization improved the surface properties. The sample subjected to both treatments showed the highest photocatalytic activity. These results indicate that CdS/ZnS core-shell microspheres are a simple structure that can be used as efficient photocatalysts. The hydrothermal sulfurization treatment may also be a useful surface treatment for metal sulfide photocatalysts. The simple two-step method provides a promising approach to the large-scale synthesis of core-shell microsphere catalysts.
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      PubDate: 2017-04-10T02:08:53Z
       
  • Fabrication of porous g-C3N4 and supported porous g-C3N4 by a simple
           precursor pretreatment strategy and their efficient visible-light
           photocatalytic activity
    • Abstract: Publication date: March 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 3
      Author(s): Zhenxing Zeng, Kexin Li, Kai Wei, Yuhua Dai, Liushui Yan, Huiqin Guo, Xubiao Luo
      Porous g-C3N4 and supported porous g-C3N4 were fabricated for the first time by a simple strategy using pretreated melamine as a raw material and pretreated quartz rod as a substrate. The formation of a richly porous microstructure can be attributed to the co-existence of different pore-fabricating units in the preparation system for porous g-C3N4. The richly porous microstructure endowed the as-prepared porous g-C3N4 with an excellent photocatalytic activity. The as-prepared supported porous g-C3N4 exhibited considerable stability because of the existence of chemical interaction between porous g-C3N4 and the quartz rod substrate. The photocatalytic activity of the supported porous g-C3N4 was competitive with that of porous g-C3N4 in powder form because neither the surface migration of photogenerated electrons nor the diffusion of the target organic pollutant were affected by the construction of the quartz rod reactor. The photocatalytic activity of the as-prepared porous g-C3N4 and supported porous g-C3N4 was preliminarily evaluated by the treatment of single-component organic wastewater under visible-light irradiation. Subsequently, the as-prepared porous g-C3N4 was further applied in conventional hydrogen evolution and a new system for simultaneous hydrogen evolution with organic-pollutant degradation. The hydrogen yield and degradation efficiency both increased with increasing photocatalytic activity of the as-prepared materials in the system for simultaneous hydrogen evolution with organic-pollutant degradation.
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      PubDate: 2017-04-10T02:08:53Z
       
  • Zinc-modified Pt/SAPO-11 for improving the isomerization selectivity to
           dibranched alkanes
    • Abstract: Publication date: March 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 3
      Author(s): Zhichao Yang, Yunqi Liu, Jinchong Zhao, Jianxia Gou, Kaian Sun, Chenguang Liu
      Zinc-modified Pt/SAPO-11 catalysts were prepared by incipient wetness impregnation and assessed in the hydroisomerization of n-octane. Their physicochemical properties were investigated using powder X-ray diffraction, scanning electron microscopy, nitrogen adsorption-desorption, pyridine-adsorbed infrared spectroscopy, temperature-programmed desorption of NH3, temperature-programmed reduction of hydrogen, temperature-programmed desorption of hydrogen, transmission electron microscopy, and X-ray photoelectron spectroscopy. The addition of zinc resulted in high dispersion of platinum. Zinc acted as a competitive adsorbent, changed the location of platinum. The catalyst with a zinc loading of 0.5% gave the highest selectivity to dimethylhexanes, but the conversion was lower than those achieved with the other catalysts. Dimethylhexanes have large molecular diameters, and therefore their diffusion may be difficult. This weakens the catalytic activity of the zinc-modified catalysts and lowers the n-octane conversion.
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      PubDate: 2017-04-10T02:08:53Z
       
  • One-pot synthesis of ordered mesoporous Cu-KIT-6 and its improved
           catalytic behavior for the epoxidation of styrene: Effects of the pH value
           of the initial gel
    • Abstract: Publication date: March 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 3
      Author(s): Baitao Li, Xin Luo, Jing Huang, Xiujun Wang, Zhenxing Liang
      The heterogeneously copper-catalyzed oxidative cleavage of styrene was studied using copper-doped mesoporous KIT-6 (Cu-KIT-6 x ) prepared via pH adjustment (where x is the pH: 1.43, 2.27, 3.78, 3.97, 4.24 or 6.62). Variations in the catalyst structure and morphology with pH values were characterized by X-ray power diffraction, nitrogen adsorption-desorption analysis, transmission electron microscopy and X-ray photoelectron spectroscopy. As the pH value applied during the initial synthesis, the resulting Cu-KIT-6 x exhibited different structural, textural and surface characteristics, especially in terms of specific copper species and copper content. At a pH value of 3.78, approximately 4.6 wt% copper(II) was successfully incorporated into the framework of the initial KIT-6, in the form of –Cu–O–Si– groups. The catalytic performance of each catalyst was evaluated by following the epoxidation of styrene, employing tert-butyl hydroperoxide as the oxidant and CH3CN as the solvent. A significant styrene conversion of 43.5% with 86.6% selectivity for the desired styrene epoxide was obtained over the Cu-KIT-63.78. A higher Cu content, an ordered cubic Ia3d mesoporous architecture and various specific textural characteristics all combined to endow the Cu-KIT-63.78 with high catalytic activity and good stability.
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      PubDate: 2017-04-10T02:08:53Z
       
  • PtSnNa/SUZ-4: An efficient catalyst for propane dehydrogenation
    • Abstract: Publication date: March 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 3
      Author(s): Hualan Zhou, Jingjing Gong, Bolian Xu, Shengcai Deng, Yuanhua Ding, Lei Yu, Yining Fan
      The structure and catalytic properties of PtSn catalysts supported on SUZ-4 and ZSM-5 zeolite have been studied by using various experimental techniques including XRD, nitrogen adsorption, NH3-TPD, TG, H2-TPR and TPO techniques combined with propane dehydrogenation tests. It has been shown that SUZ-4-supported PtSnNa (PtSnNa/SUZ-4) was determined to be a better catalyst for propane dehydrogenation than conventional catalysts supported on ZSM-5, owing to its higher catalytic activity and stability. Dibenzothiophene poisoning experiments were performed to investigate the detailed structures of the two supported catalysts. The characterization of the two catalysts indicates that the distribution of Pt on the porous support affects the activity. In contrast to ZSM-5-supported catalysts, Pt particles on the PtSnNa/SUZ-4 are primarily dispersed over the external surface and are not as readily deactivated by carbon deposition. This is because that the strong acid sites of the SUZ-4 zeolite evidently prevented the impregnation of the Pt precursor H2PtCl6 into the zeolite. In contrast, the weak acid sites of the ZSM-5 zeolite led to more of the precursor entering the zeolite tunnels, followed by transformation to highly dispersed Pt clusters during calcination. In the case of the PtSnNa/ZSM-5, the interactions between Sn oxides and the support were lessened, owing to the weaker acidity of the ZSM-5 zeolite. The dispersed Sn oxides were therefore easier to reduce to the metallic state, thus decreasing the catalytic activity for hydrocarbon dehydrogenation.
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      PubDate: 2017-04-10T02:08:53Z
       
  • Selective glycerol oxidation using platinum nanoparticles supported on
           multi-walled carbon nanotubes and nitrogen-doped graphene hybrid
    • Abstract: Publication date: March 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 3
      Author(s): Mengyuan Zhang, Yanyan Sun, Juanjuan Shi, Wensheng Ning, Zhaoyin Hou
      Selective oxidation of glycerol is a hot topic. Increased biodiesel production has led to glycerol oxidation over Au- and Pt-based catalysts being widely studied. However, Pt catalysts suffer from deactivation because of weak metal-support interactions. In this study, multi-walled carbon nanotube (MWCNTs)-pillared nitrogen-doped graphene (NG) was prepared by direct pyrolysis of melamine on MWCNTs, and the synthesized NG-MWCNT composite was used as the support for Pt. Characterization results showed that the surface area (173 m2/g) and pore volume of the NG-MWCNT composite were greater than those of bare MWCNTs and the separated melamine pyrolysis product (CN x ). Pt (1.4 ± 0.4 nm) dispersion on the NG-MWCNTs was favorable and the Pt/NG-MWCNT catalyst was highly active and selective in the oxidation of glycerol to glyceric acid (GLYA) in base-free aqueous solution. For example, the conversion of glycerol reached 64.4% with a GLYA selectivity of 81.0%, whereas the conversions of glycerol over Pt/MWCNTs and Pt/CN x were 29.0% and 31.6%, respectively. The unique catalytic activity of the Pt/NG-MWCNTs is attributed to well-dispersed Pt clusters on the NG-MWCNTs and the electron-donating effect of the nitrogen dopant in the NG-MWCNTs.
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      PubDate: 2017-04-10T02:08:53Z
       
  • Gold nanoparticle stabilization within tailored cubic mesoporous silica:
           Optimizing alcohol oxidation activity
    • Abstract: Publication date: March 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 3
      Author(s): Wei Hong, Xiaoqing Yan, Renhong Li, Jie Fan
      Stabilizing gold nanoparticles (AuNPs) within a desired size range is critical to realize their promising catalytic performance in many important reactions. Herein, we investigate the anti-sintering properties of cubic mesoporous silica (FDU-12) as a function of pore entrance size. Simple adjustments to the type of organic template and reaction temperature enable the successful synthesis of FDU-12 with controllable entrance sizes (< 3, 3–5 and 7 nm). Excellent anti-sintering properties are observed for FDU-12 with a sub-5-nm entrance size (3–5 nm) over a wide loading concentration (1.0–8.3 wt%) and the AuNPs can be stabilized within a 4.5–5.0-nm range after calcination at 550 °C in air for 5 h. Smaller entrance size (< 3 nm) prevents ingress of 3-nm AuNPs to the mesopores and results in low loading capacity and sintering. Conversely, FDU-12 possessing a larger entrance size (7 nm) shows promising anti-sintering properties at high loading concentrations, although catalytic performance is significantly lost at lower concentrations (e.g. 2.1 wt%, 14.2 ± 5.5 nm). Different anti-sintering mechanisms are proposed for each of the different FDU-12 entrance sizes. Additionally, catalytic data indicates that the obtained 4.5-nm AuNPs supported on FDU-12 with a sub-5-nm entrance size exhibit excellent mass-specific activity (1544 mmol gAu –1 h–1) and selectivity (> 99%) at 230 °C for the gas-phase selective oxidation of cyclohexanol.
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      PubDate: 2017-04-10T02:08:53Z
       
  • Promoting effects of Fe2O3 to Pt electrocatalysts toward methanol
           oxidation reaction in alkaline electrolyte
    • Abstract: Publication date: March 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 3
      Author(s): Guihua Song, Haifang Yang, Yafei Sun, Jingyi Wang, Weidong Qu, Qiang Zhang, Lingjuan Ma, Yuanyuan Feng
      Fe2O3 nanorods and hexagonal nanoplates were synthesized and used as the promoters for Pt electrocatalysts toward the methanol oxidation reaction (MOR) in an alkaline electrolyte. The catalysts were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, cyclic voltammetry and chronoamperometry. The results show that the presence of Fe2O3 in the electrocatalysts can promote the kinetic processes of MOR on Pt, and this promoting effect is related to the morphology of the Fe2O3 promoter. The catalyst with Fe2O3 nanorods as the promoter (Pt-Fe2O3/C-R) exhibits much higher catalytic activity and stability than that with Fe2O3 nanoplates as the promoter (Pt-Fe2O3/C-P). The mass activity and specific activity of Pt in a Pt-Fe2O3/C-R catalyst are 5.32 A/mgPt and 162.7 A/m2 Pt, respectively, which are approximately 1.67 and 2.04 times those of the Pt-Fe2O3/C-P catalyst, and 4.19 and 6.16 times those of a commercial PtRu/C catalyst, respectively. Synergistic effects between Fe2O3 and Pt and the high content of Pt oxides in the catalysts are responsible for the improvement. These findings contribute not only to our understanding of the MOR mechanism but also to the development of advanced electrocatalysts with high catalytic properties for direct methanol fuel cells.
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      PubDate: 2017-04-10T02:08:53Z
       
  • Catalytic performance of Ag/Co-Ce composite oxides during soot combustion
           in O2 and NOx: Insights into the effects of silver
    • Abstract: Publication date: March 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 3
      Author(s): Guchu Zou, Zeyun Fan, Xin Yao, Yi Zhang, Zhixiang Zhang, Mingxia Chen, Wenfeng Shangguan
      The composite oxides xAg/Co0.93Ce0.07 (x = Ag/(Co+Ce) molar ratio), intended for use as high performance catalytic materials, were successfully prepared via citric acid complexation. The effects of silver on the performance of these substances during soot combustion were subsequently investigated. Under O2, the 0.3Ag/Co0.93Ce0.07 catalyst resulted in the lowest ignition temperature, T 10, of 197 °C, while the minimum light-off temperature was obtained from both 0.2Ag/Co0.93Ce0.07 and 0.3Ag/Co0.93Ce0.07 in the NO x atmosphere. These materials were also characterized by various techniques, including H2, soot and NO x temperature programmed reduction, X-ray diffraction, and electron paramagnetic resonance, Raman, X-ray photoelectron, and Fourier transform infrared spectroscopic analyses. The results demonstrated that silver significantly alters the catalytic behavior under both O2 and NO x , even though the lattice structure of the mixed oxide is not affected. Surface silver oxides generated under the O2 atmosphere favor soot combustion by participating in the redox cycles between soot and the silver oxide, whereas the AgNO3 that forms in a NO x -rich atmosphere facilitates soot abatement at a lower temperature. The inferior activity of AgNO3 relative to that of Ag2O results in the different catalytic performance in the presence of NO x or O2.
      Graphical abstract image

      PubDate: 2017-04-10T02:08:53Z
       
  • SAPO-34 synthesized with n-butylamine as a template and its catalytic
           application in the methanol amination reaction
    • Abstract: Publication date: March 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 3
      Author(s): Yuyan Qiao, Pengfei Wu, Xiao Xiang, Miao Yang, Quanyi Wang, Peng Tian, Zhongmin Liu
      SAPO-34 was synthesized with n-butylamine (BA) as a template for the first time. Crystallization temperature and initial Si amount were important factors leading to successful syntheses. Lamellar AlPO-kanemite tends to form as the major phase or as an impurity of SAPO-34 at lower crystallization temperatures, though a higher initial Si amount may offer a positive effect on the crystallization of SAPO-34 that mitigates the low temperature. Higher temperature (240 °C) can effectively suppress the generation of lamellar materials and allow the synthesis of pure SAPO-34 with a wider range of Si incorporation. The crystallization processes at 200 and 240 °C were investigated and compared. We used the aminothermal method to synthesize SAPO-34-BA at 240 °C and also found n-propylamine is a suitable template for the synthesis of SAPO-34. The SAPO-34-BA products were characterized by many techniques. SAPO-34-BA has good thermal stability, crystallinity and porosity. BA remained intact in the crystals with ∼1.8 BA molecule per chabazite cage. The catalytic performance of SAPO-34 was tested in the methanol amination reaction, which showed high methanol conversion and selectivity for methylamine plus dimethylamine under the conditions investigated, suggesting that this material is a good candidate for the synthesis of methylamines.
      Graphical abstract image

      PubDate: 2017-04-10T02:08:53Z
       
  • Environmentally benign and economic synthesis of covalent triazine-based
           frameworks
    • Abstract: Publication date: March 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 3
      Author(s): Ling Zhang, Xue Liu, Rui-Xia Yang, Nian-Yu Huang, Wei-Qiao Deng
      Covalent triazine-based frameworks (CTFs) are important microporous materials with a wide range of applications. Here, we demonstrate an environmentally benign and economic synthetic pathway to CTFs. The monomers used for CTFs, aromatic nitriles, were obtained by cyanation using nontoxic potassium hexacyanoferrate(II) in place of commonly used toxic cyanides. Then, the CTFs were synthesized by trimerization of the corresponding cyano monomers in molten zinc chloride. A series of CTFs was synthesized, and the highest Brunauer-Emmett-Teller surface area measured in this series was 2404 m2/g. Among the synthesized CTFs, CTFDCP exhibited excellent CO2 adsorption properties, with a CO2 uptake of 225 mg/g at 0 °C.
      Graphical abstract image

      PubDate: 2017-04-10T02:08:53Z
       
  • Palladium nanoparticles in cross-linked polyaniline as highly efficient
           catalysts for Suzuki-Miyaura reactions
    • Abstract: Publication date: March 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 3
      Author(s): Haipeng Fan, Zhengliang Qi, Dejun Sui, Fei Mao, Rizhi Chen, Jun Huang
      Palladium nanoparticles supported on cross-linked polyaniline with bulky phosphorus ligands were developed. These catalysts showed high efficiency in the Suzuki-Miyaura reaction of aryl chlorides and bromides with phenylboronic acids. Aryl chlorides and bromides with functional groups, such as CN, MeO, CHO, MeCO and NO2, were converted to the corresponding biphenyls in high yields with catalyst loading. Additionally, the catalysts combined high activity with good reusability; they could be used at least five times for the Suzuki-Miyaura coupling reaction.
      Graphical abstract image

      PubDate: 2017-04-10T02:08:53Z
       
  • Surfactant-assisted hydrothermally synthesized MoS2 samples with
           controllable morphologies and structures for anthracene hydrogenation
    • Abstract: Publication date: March 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 3
      Author(s): Min Li, Donge Wang, Jiahe Li, Zhendong Pan, Huaijun Ma, Yuxia Jiang, Zhijian Tian, Anhui Lu
      MoS2 samples with controllable morphologies and structures were synthesized using surfactant-assisted hydrothermal processes. The effects of surfactants (PEG, PVP, P123, SDS, AOT, and CTAB) on the morphologies and structures of MoS2 samples were investigated. The results revealed that spherical, bulk-like, and flower-like MoS2 particles assembled by NH4 +-intercalated MoS2 nano-sheets were synthesized. The morphologies of the MoS2 samples and their structures (including the slab length and the number of stacked layers) of MoS2 nano-sheets in these samples could be controlled by adjusting the surfactants. Mono-dispersed spherical MoS2 particles could be synthesized with PEG via the creation of MoS2 nano-sheets with slab lengths shorter than 15 nm and fewer than six stacked layers. Possible formation mechanisms of these MoS2 samples created via surfactant-assisted hydrothermal processes are proposed. Further, the catalytic activities of MoS2 samples for anthracene hydrogenation were evaluated in a slurry-bed reactor. The catalyst synthesized with the surfactant PEG exhibited the highest catalytic hydrogenation activity. Compared with the other catalysts, it had a smaller particle size, mono-dispersed spherical morphology, shorter slab length, and fewer stacked layers; these were all beneficial to exposing its active edges. This work provides an efficient approach to synthesize transition metal sulfides with controllable morphologies and structures.
      Graphical abstract image

      PubDate: 2017-04-10T02:08:53Z
       
  • Propene and CO oxidation on Pt/Ce-Zr-SO42– diesel oxidation catalysts:
           Effect of sulfate on activity and stability
    • Abstract: Publication date: March 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 3
      Author(s): Lei Gu, Xiao Chen, Ying Zhou, Qiulian Zhu, Haifeng Huang, Hanfeng Lu
      Platinum/cerium-zirconium-sulfate (Pt/Ce-Zr-SO4 2–) catalysts were prepared by wetness impregnation. Catalytic activities were evaluated from the combustion of propene and CO. Sulfate (SO4 2–) addition improved the catalytic activity significantly. When using Pt/Ce-Zr-SO4 2– with 10 wt% SO4 2–, the temperature for 90% conversion of propene and CO decreased by 75 °C compared with Pt/Ce-Zr. The conversion exceeded 95% at 240 °C even after 0.02% sulfur dioxide poisoning for 20 h. Temperature-programmed desorption of CO and X-ray photoelectron spectroscopy analyses revealed an improvement in Pt dispersion onto the Ce-Zr-SO4 2– support, and the increased number of Pt particles built up more Pt&+-(SO4 2–)&– couples, which resulted in excellent activity. The increased total acidity and new Brönsted acid sites on the surface provided the Pt/Ce-Zr-SO4 2– with good sulfur resistance.
      Graphical abstract image

      PubDate: 2017-04-10T02:08:53Z
       
  • Preface to Special Issue on the International Symposium on Environmental
           Catalysis (ISEC 2016)
    • Abstract: Publication date: February 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 2
      Author(s): Jinlin Li, Jiaguo Yu


      PubDate: 2017-03-13T00:21:57Z
       
  • Photochemical oxidation mechanism of microcystin-RR by p-n heterojunction
           Ag/Ag2O-BiVO4
    • Abstract: Publication date: February 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 2
      Author(s): Chunhong Wu, Yanfen Fang, Araya Hailu Tirusew, Miaomiao Xiang, Yingping Huang, Chuncheng Chen
      Microcystin-RR (MC-RR), a form of microcystin with two arginine moieties, is a cyanobacterial toxin that has been detected across a wide geographic range. It is a great concern globally because of its potential liver toxicity. Herein, the abilities of BiVO4, Ag-BiVO4, Ag2O-BiVO4 and Ag/Ag2O-BiVO4 to photocatalytically degrade MC-RR under visible-light irradiation (λ ≥ 420 nm) were investigated and compared. The possible degradation pathways were explored through analysis of the reaction intermediates by high-performance liquid chromatography-mass spectrometry. The results showed that the presence of Ag0 enhanced the photocatalytic efficiency of Ag/Ag2O-BiVO4 via a synergetic effect between Ag2O and Ag0 at the p-n heterojunction. Moreover, the presence of Ag0 also greatly promoted the adsorption of MC-RR on the photocatalyst surface. Toxicological experiments on mice showed that the toxicity of MC-RR was significantly reduced after photocatalytic degradation.
      Graphical abstract image

      PubDate: 2017-03-13T00:21:57Z
       
  • Effects of hierarchical structure on the performance of tin
           oxide-supported platinum catalyst for room-temperature formaldehyde
           oxidation
    • Abstract: Publication date: February 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 2
      Author(s): Yuanyuan Duan, Shaoqing Song, Bei Cheng, Jiaguo Yu, Chuanjia Jiang
      Flower-like tin oxide-supported platinum (Pt/SnO x ) with a hierarchical structure was synthesized by a hydrothermal method and characterized by XRD, SEM, TEM, high resolution TEM, XPS and nitrogen adsorption. The flower-like Pt/SnO x microspheres of 1 μm in diameter were composed of staggered petal-like nanosheets with a thickness of 20 nm. Pt nanoparticles (NPs) of 2–3 nm were well dispersed on the SnO x nanosheets. The catalyst was tested in the catalytic oxidation of gaseous formaldehyde (HCHO) at room temperature, and exhibited enhanced activity compared to Pt NPs supported on commercial SnO and ground SnO x . HCHO removal of 87% was achieved over the hierarchical Pt/SnO x after 1 h of reaction, which was 1.5 times that over the ground SnO x -supported Pt (Pt/g-SnO x ), and the high activity was maintained after six recycles, showing the high stability of this catalyst. HCHO decomposition kinetics was modeled as a second order reaction. The reaction rate constant for Pt/SnO x was 5.6 times higher than Pt/g-SnO x . The hierarchical pore structure was beneficial for the diffusion and adsorption of HCHO molecules, and the highly dispersed Pt NPs on the SnO x nanosheets were the active sites for the oxidative decomposition of HCHO into CO2 and H2O. This study provided a promising approach for designing efficient catalysts for indoor HCHO removal at ambient temperature.
      Graphical abstract image

      PubDate: 2017-03-13T00:21:57Z
       
  • Catalytic performance of cobalt oxide-supported gold-palladium
           nanocatalysts for the removal of toluene and o-xylene
    • Abstract: Publication date: February 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 2
      Author(s): Zhiwei Wang, Yuxi Liu, Tao Yang, Jiguang Deng, Shaohua Xie, Hongxing Dai
      Using the molten salt and polyvinyl alcohol-protected reduction method, we fabricated Co3O4 octahedron-supported Au-Pd (x(AuPd y )/Co3O4; x = (0.18, 0.47, and 0.96) wt%; y (Pd/Au molar ratio) = 1.85−1.97) nanocatalysts. The molten salt-derived Co3O4 sample possessed well-defined octahedral morphology, with an edge length of 300 nm. The Au-Pd nanoparticles, with sizes of 2.7−3.2 nm, were uniformly dispersed on the surface of Co3O4. The 0.96 (AuPd1.92)/Co3O4 sample showed the highest catalytic activity for toluene and o-xylene oxidation, and the temperature required for achieving 90% conversion of toluene and o-xylene was 180 and 187 °C, respectively, at a space velocity of 40000 mL/(g–h). The high catalytic performance of Co3O4 octahedron-supported Au-Pd nanocatalysts was associated with the interaction between Au-Pd nanoparticles and Co3O4 and high concentration of adsorbed oxygen species.
      Graphical abstract image

      PubDate: 2017-03-13T00:21:57Z
       
  • Heterostructured BiOI@La(OH)3 nanorods with enhanced visible light
           photocatalytic NO removal
    • Abstract: Publication date: February 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 2
      Author(s): Yanjuan Sun, Xiang Xiao, Xing'an Dong, Fan Dong, Wei Zhang
      Heterostructured BiOI@La(OH)3 nanorod photocatalysts were prepared by a facile chemical impregnation method. The enhanced visible light absorption and charge carrier separation can be simultaneously realized after the introduction of BiOI particles into La(OH)3 nanorods. The BiOI@La(OH)3 composites were applied for visible light photocatalytic oxidization of NO in air and exhibited an enhanced activity compared with BiOI and pure La(OH)3 nanorods. The results show that the energy levels between the La(OH)3 and BiOI phases matched well with each other, thus forming a heterojunctioned BiOI@La(OH)3 structure. This band structure matching could promote the separation and transfer of photoinduced electron-hole pairs at the interface, resulting in enhanced photocatalytic performance under visible light irradiation. The photocatalytic performance of BiOI@La(OH)3 is shown to be dependent on the mass ratio of BiOI to La(OH)3. The highest photocatalytic performance can be achieved when the mass ratio of BiOI to La(OH)3 is controlled at 1.5. A further increase of the mass ratio of BiOI weakened the redox abilities of the photogenerated charge carriers. A new photocatalytic mechanism for BiOI@La(OH)3 heterostructures is proposed, which is directly related to the efficient separation of photogenerated charge carriers by the heterojunction. Importantly, the as-prepared BiOI@La(OH)3 heterostructures exhibited a high photochemical stability after multiple reaction runs. Our findings demonstrate that BiOI is an effective component for the formation of a heterostructure with the properties of a wide bandgap semiconductor, which is of great importance for extending the light absorption and photocatalytic activity of wide bandgap semiconductors into visible light region.
      Graphical abstract image

      PubDate: 2017-03-13T00:21:57Z
       
  • Heterogeneous catalytic activation of peroxymonosulfate for efficient
           degradation of organic pollutants by magnetic Cu0/Fe3O4 submicron
           composites
    • Abstract: Publication date: February 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 2
      Author(s): Gang Nie, Jia Huang, Yezhou Hu, Yaobin Ding, Xiaoyan Han, Heqing Tang
      Magnetic Cu0/Fe3O4 submicron composites were prepared using a hydrothermal method and used as heterogeneous catalysts for the activation of peroxymonosulfate (PMS) and the degradation of organic pollutants. The as-prepared magnetic Cu0/Fe3O4 submicron composites were composed of Cu0 and Fe3O4 crystals and had an average size of approximately 220 nm. The Cu0/Fe3O4 composites could efficiently catalyze the activation of PMS to generate singlet oxygen, and thus induced the rapid degradation of rhodamine B, methylene blue, orange II, phenol and 4-chlorophenol. The use of 0.1 g/L of the Cu0/Fe3O4 composites induced the complete removal of rhodamine B (20 μmol/L) in 15 min, methylene blue (20 μmol/L) in 5 min, orange II (20 μmol/L) in 10 min, phenol (0.1 mmol/L) in 30 min and 4-chlorophenol (0.1 mmol/L) in 15 min with an initial pH value of 7.0 and a PMS concentration of 0.5 mmol/L. The total organic carbon (TOC) removal higher than 85% for all of these five pollutants was obtained in 30 min when the PMS concentration was 2.5 mmol/L. The rate of degradation was considerably higher than that obtained with Cu0 or Fe3O4 particles alone. The enhanced catalytic activity of the Cu0/Fe3O4 composites in the activation of PMS was attributed to the synergistic effect of the Cu0 and Fe3O4 crystals in the composites. Singlet oxygen was identified as the primary reactive oxygen species responsible for pollutant degradation by electron spin resonance and radical quenching experiments. A possible mechanism for the activation of PMS by Cu0/Fe3O4 composites is proposed as electron transfer from the organic pollutants to PMS induces the activation of PMS to generate 1O2, which induces the degradation of the organic pollutants. As a magnetic catalyst, the Cu0/Fe3O4 composites were easily recovered by magnetic separation, and exhibited excellent stability over five successive degradation cycles. The present study provides a facile and green heterogeneous catalysis method for the oxidative removal of organic pollutants.
      Graphical abstract image

      PubDate: 2017-03-13T00:21:57Z
       
  • Enhanced visible light photocatalytic H2 production over Z-scheme g-C3N4
           nansheets/WO3 nanorods nanocomposites loaded with Ni(OH)x cocatalysts
    • Abstract: Publication date: February 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 2
      Author(s): Kelin He, Jun Xie, Xingyi Luo, Jiuqing Wen, Song Ma, Xin Li, Yueping Fang, Xiangchao Zhang
      Novel WO3/g-C3N4/Ni(OH) x hybrids have been successfully synthesized by a two-step strategy of high temperature calcination and in situ photodeposition. Their photocatalytic performance was investigated using TEOA as a hole scavenger under visible light irradiation. The loading of WO3 and Ni(OH) x cocatalysts boosted the photocatalytic H2 evolution efficiency of g-C3N4. WO3/g-C3N4/Ni(OH) x with 20 wt%defective WO3 and 4.8 wt%Ni(OH) x showed the highest hydrogen production rate of 576 μmol/(g–h), which was 5.7, 10.8 and 230 times higher than those of g-C3N4/4.8 wt%Ni(OH) x , 20 wt%WO3/C3N4 and g-C3N4 photocatalysts, respectively. The remarkably enhanced H2 evolution performance was ascribed to the combination effects of the Z-scheme heterojunction (WO3/g-C3N4) and loaded cocatalysts (Ni(OH) x ), which effectively inhibited the recombination of the photoexcited electron-hole pairs of g-C3N4 and improved both H2 evolution and TEOA oxidation kinetics. The electron spin resonance spectra of •O2 − and •OH radicals provided evidence for the Z-scheme charge separation mechanism. The loading of easily available Ni(OH) x cocatalysts on the Z-scheme WO3/g-C3N4 nanocomposites provided insights into constructing a robust multiple-heterojunction material for photocatalytic applications.
      Graphical abstract image

      PubDate: 2017-03-13T00:21:57Z
       
  • Highly efficient Z-scheme WO3–x quantum dots/TiO2 for photocatalytic
           hydrogen generation
    • Abstract: Publication date: February 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 2
      Author(s): Lun Pan, Jingwen Zhang, Xu Jia, Yu-Hang Ma, Xiangwen Zhang, Li Wang, Ji-Jun Zou
      Z-scheme semiconductors are a promising class of photocatalysts for hydrogen generation. In this work, Z-scheme semiconductors composed of WO3–x quantum dots supported on TiO2 (WO3–x QDs/TiO2) were fabricated by solvothermal and hydrogen-reduction methods. Characterization by transmission electron microscopy and X-ray diffraction indicated that the amount and size of the WO3–x QDs could be tuned by modulating the addition of the W precursor. Evidence from X-ray photoelectron spectroscopy and photoluminescence spectroscopy suggested that the hydrogen reduction of the composite induced the formation of oxygen vacancy (W5+/VO) defects in WO3. These defects led to ohmic contact between WO3-x and TiO2, which altered the charge-transfer pathway from type II heterojunction to Z-scheme, and maintained the highly reductive and oxidative ability of TiO2 and WO3–x , respectively. Therefore, the Z-scheme sample showed 1.3-fold higher photoactivity than pure TiO2 in hydrogen generation. These results suggest that the formation of W5+/VO defects at the interface is highly beneficial for the fabrication of Z-scheme photocatalysts.
      Graphical abstract image

      PubDate: 2017-03-13T00:21:57Z
       
  • Surface plasmon resonance-induced visible-light photocatalytic performance
           of silver/silver molybdate composites
    • Abstract: Publication date: February 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 2
      Author(s): Xianglong Yang, Ying Wang, Xiao Xu, Yang Qu, Xing Ding, Hao Chen
      Novel silver/silver molybdate (Ag/Ag2MoO4) composites with surface plasmon resonance (SPR)-enhanced photocatalytic performance were successfully fabricated via a facile one-pot hydrothermal route with the presence of sodium dodecyl sulfate (SDS) in this study. The as prepared silver/silver molybdate (Ag/Ag2MoO4) composites were systematically characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and ultraviolet-visible diffuse reflectance absorption spectroscopy (DRS) in order to investigate their crystal structure, morphology and optical property as well. The photocatalytic activities of the composites were subsequently evaluated by their ability to degrade rhodamine B (RhB) under visible-light irradiation. Varies of controlled experiments were then carefully operated to gain a deep insight into the assembling of Ag/Ag2MoO4 composites. It was found that preparation conditions such as pH, reaction time, and the amount of surfactant played important roles in the formation of composites with octahedral microstructures. And the composite obtained at 160 °C using 0.5 g of sodium dodecyl sulfate exhibited the highest photocatalytic performance under visible-light irradiation. Capture experiments were also conducted to clarify the function of different active species generated on the surface of Ag/Ag2MoO4 during the photocatalytic process, in which both holes and •OH radicals were found to play crucial role in photocatalytic removal of RhB under visible light irradiation. A possible photocatalytic mechanism of Ag/Ag2MoO4 was finally proposed on the basis of all the results to explain the higher photocatalytic activity of the octahedral Ag/Ag2MoO4 composites. It was inferred that the photoinduced “hot” electrons can quickly transfer from the Ag NPs to the conduction band of Ag2MoO4 and react with oxygen and H2O to generate a large quality of active radicals such as •OH and •O2 − because of the SPR effects. Besides, this SPR effects of Ag nanoparticles deposited on the surface of Ag2MoO4 can not only dramatically amplify its light absorption, especially in the visible region, but also promote the separation of photoexcited electron-hole pairs and effectively decrease electron-hole recombination.
      Graphical abstract image

      PubDate: 2017-03-13T00:21:57Z
       
  • Heterojunction between anodic TiO2/g-C3N4 and cathodic WO3/W
           nano-catalysts for coupled pollutant removal in a self-biased system
    • Abstract: Publication date: February 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 2
      Author(s): Tingting Yu, Lifen Liu, Fenglin Yang
      An anodic TiO2/g-C3N4 hetero-junction and cathodic WO3/W were used to build a self-sustained catalytic fuel cell system for oxidizing rhodamine B or triclosan and reducing NO3 −-N to N2 simultaneously. The WO3 nano-catalyst was formed in situ by heating and oxidizing a tungsten wire in air. Cyclic voltammetry and current-time curves were used to characterize the electrochemical properties of the electrodes and system. Aeration and activation of molecular oxygen by self-biased TiO2/g-C3N4 led to the formation of reactive oxidizing species in the fuel cell. The mechanism of simultaneous anodic oxidation of pollutants and cathodic reduction of nitrate was proposed. The spontaneously formed circuit and tiny current were used simultaneously in treating two kinds of wastewater in the reactor chambers, even without light illumination or an external applied voltage. This new catalytic pollution control route can lower energy consumption and degrade many other kinds of pollutants.
      Graphical abstract image

      PubDate: 2017-03-13T00:21:57Z
       
  • Enhanced photochemical oxidation ability of carbon nitride by π–π
           stacking interactions with graphene
    • Abstract: Publication date: February 2017
      Source:Chinese Journal of Catalysis, Volume 38, Issue 2
      Author(s): Qiang Hao, Simeng Hao, Xiuxiu Niu, Xun Li, Daimei Chen, Hao Ding
      A one-pot method for the preparation of g-C3N4/reduced graphene oxide (rGO) composite photocatalysts with controllable band structures is presented. The photocatalysts are characterized by Fouirer transform infrared spectroscopy, X-ray diffraction, scanning electron microscope, transmission electron microscope, and Mott-Schottky analysis. The valance band (VB) of g-C3N4 exhibits a noticeable positive shift upon hybridizing with rGO, and thus results in a strong photo-oxidation ability. The g-C3N4/rGO composites show a higher photodegradation activity for 2,4-dichlorophenol (2,4-DCP) and rhodamine B (RhB) under visible light irradiation (λ ≥ 420 nm). The g-C3N4/rGO-1 sample exhibits the highest photocatalytic activity, which is 1.49 and 1.52 times higher than that of bulk g-C3N4 for 2,4-DCP and 1.52 times degradation, respectively. The enhanced photocatalytic activity for g-C3N4 originates from the improved visible light usage, enhanced electronic conductivity and photo-oxidation ability by the formed strong π–π stacking interactions with rGO.
      Graphical abstract image

      PubDate: 2017-03-13T00:21:57Z
       
 
 
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