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Swallowtail model for predicting the global bifurcation behavior of co oxidation reactions

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Science China Chemistry 2011年第7期54卷 1072-1077页

作者： CUI Tao TANG ShunLin ZHANG Lei YU DaRen School of Energy Science and Engineering Harbin Institute of Technology Harbin 150001 China Pharmaceutical college Heilongjiang University of Chinese Medicine Institution Harbin 150040 China

Catalytic co oxidation on platinum group metals exhibits nonlinear phenomena such as hysteresis and *** of the nonlinear mechanisms is important for catalyst design and control of reaction *** studies have offered initial insights into the local bifurcation behavior of co ***,since the bifurcation behavior of co oxidation is determined by multiple parameters such as temperature,total flux,and co fraction,it is difficult to predict the global bifurcation behavior in the resulting high-dimensional parameter *** is for this reason that the observed nonlinear phenomena reflect just the local bifurcation features of co *** this paper,an elementary chemical law(topological invariance) concerning the bifurcation behavior of co oxidation on platinum group metals such as Pd(111) is found from a topological *** the elementary law,we put forward a topological approach to model the critical criteria for the reaction hysteresis and *** model may be applied to predict the global bifurcation behavior of co oxidation in the high-dimensional parameter *** topological approach and the model results may be useful as a guide in thinking about the complex reaction mechanism,designing reaction routes,and actively controlling the bifurcation behavior of the co oxidation reaction.

关键词： co oxidation bifurcation hysteresis

Effect of Support Calcination Temperature on Ag Structure and Catalytic Activity for co oxidation

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Chemical Research in Chinese Universities 2016年第3期32卷 455-460页

作者： ZHANG Xiaodong DONG Han ZHAO Di WANG Yin WANG Yangang CUI Lifeng Environment and Low-carbon Research Center School of Environment and Architecture University of Shanghai for Science and Technology Shanghai 200093 P. R. China

SiO2 with different nanostructures, namely hexagonal mesoporous silica（HMS）, and three unordered commercial silica, were used as supports to fabricate silver catalysts using an incipient wetness impregnation method. It was found that Ag/HMS catalyst showed a high catalytic activity. Next, the HMS support was calcined at different temperatures before impregnation of AgNO3. The effect of calcination temperature of HMS support was investigated in terms of structure and catalytic activity of Ag catalysts. The support and catalysts were characterized by N2 ad- sorption-desorption isotherms, Thermogravimetric-differential thermal analyzer, X-ray diffraction, Hz-temperature program reduction and transmission electron microscopy. The results showed that calcination of HMS at an appropriate temperature（750 ℃） before catalyst preparation would benefit the formation of highly dispersive small sized Ag particles on the HMS support and markedly enhance the catalytic activity of Ag/HMS catalyst toward co oxidation.

关键词： Ag catalyst co oxidation SiO2 Calcination Support

Immobilizing ultrafine bimetallic PtAg alloy onto uniform MnO_(2) microsphere as a highly active catalyst for co oxidation

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Chinese Chemical Letters 2021年第6期32卷 2057-2060页

作者： Shengpeng Mo Peng Peng Yinchang Pei Taiming Shen Qinglin Xie Mingli Fu Yunfa Chen Daiqi Ye college of Environment Science and Engineering Guilin University of TechnologyGuilin 541004China School of Environment and Energy South China University of TechnologyGuangzhou 510006China Guangxi Key Laboratory of Theory and Technology for Environmental Pollution control Guilin University of TechnologyGuilin 541004China State Key Laboratory of Multi-Phase complex Systems Institute of Process EngineeringChinese Academy of SciencesBeijing 100190China

Herein,a facile glycol reduction route is successful employed to synthesize bimetallic Pt Ag alloys with homogeneous distribution of sizes and *** studies reveal that the ultrafine Pt Ag alloys with well-defined sizes from around 3.3 nm to 5.8 nm are immobilized onto MnO_(2)microsphere,which remarkably enhances the catalytic performances for co ***,quasi in-situ X-ray photoelectron spectroscopy(XPS)result reveals that both Mn and Pt ions on the surface of catalysts would realize alternating reduction-oxidation by co and O_(2)molecules,and the oxygen vacancy sites could be replenished and excited by gas-phase O_(2).

关键词： Bimetallic alloys PtAg NPs MnO_(2) Quasi in-situ XPS co oxidation

Nanoclusters Au19Pd and Au19Pt Catalyzing co oxidation: a Density Functional Study

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Chinese Journal of Structural Chemistry 2018年第12期37卷 1849-1859,1843页

作者： ZHANG Jing YU Wei-Ling ZHOU Sheng-Hua LI Yi ZHANG Yong-Fan CHEN Wen-Kai Department of Chemistry Fuzhou UniversityFuzhou 350116China State Key Laboratory of Photocatalysis on Energy and Environment Fuzhou 350116China Fujian Provincial Key Laboratory of Theoretical and computational Chemistry Xiamen UniversityXiamen 610005China

The gold atoms on the Au20 cluster had been substituted by the palladium and platinum atoms to obtain the doped clusters with more stable geometries as a function of the bind energy and interaction energy in the previous study. Therefore, we investigated the catalytic activities of the Au_(19)Pd and Au_(19)Pt clusters for co oxidation along the Langmuir-Hinshelwood mechanism. It is found that the coadsorption of co and O2 on the doped clusters is obviously stronger than on the Au20 cluster, especially on the doped atom, which makes potential energy of the transition state lower than the total energy of the reactants so that it can promote co oxidation. The reaction on these doped clusters with the heteroatom on the vertex is more difficult. However, the Au_(19)Pd(S) is more prone to catalyzing the co oxidation, in which the rate-limiting step has the lower energy barrier of 38.84 kJ/mol for this study. Therefore, the single atom can be modified to change the catalytic activity of the cluster for the co oxidation. Meanwhile, the different sites on the clusters have different strengths of activity for the reaction.

关键词： bimetallic cluster catalytic activity co oxidation density functional theory

Synthesis of Li-doped co_3O_4 truncated octahedra with improved performances in co oxidation and lithium ion batteries

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Science China(Technological Sciences) 2013年第1期56卷 8-12页

作者： JIN Hong CUI ZhiMin ZHOU Wei GUO Lin YANG ShiHe School of Chemistry and Environment Beihang University Department of Chemistry Hong Kong University of Science and TechnologyClear Water BayKowloon

Single-crystalline Li-doped co3O4 truncated octahedra with different doping contents were synthesized by a simple combustion method with the fuel of multi-walled carbon nanotubes(MWCNTs).controlled experiments showed that the pristine well-defined co3O4 octahedra were obtained with exposed surfaces of {111} planes without lithium *** comparison with the octahedra,the truncated co3O4 octahedra were composed of original {111} planes and extra {100} *** could be attributable to the selective adsorption of lithium ions on the {100} planes,making these planes with higher surface energy coexist with the crystal faces of {111}.Furthermore,the Li-doped truncated octahedra and undoped octahedra were used as catalysts in co oxidation and as anode materials for Li-ion batteries(LIBs).The measurements exhibited that the Li-doped octahedra with added {100} crystal faces showed improved catalytic activity and electrochemical property because of the exposure of the higher energy faces of {100} and enhanced conductivity by Li doping.

关键词： truncated octahedron high-energy face doping co oxidation Li-ion battery

Relationships between the activities and Ce^(3+)concentrations of CeO_(2)(111)for co oxidation:A first-principle investigation

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Chinese Chemical Letters 2021年第3期32卷 1127-1130页

作者： Jiyuan Liu Xueqing Gong Key Laboratory for Advanced Materials Centre for Computational Chemistry and Research Institute of Industrial CatalysisSchool of Chemistry and Molecular EngineeringEast China University of Science and TechnologyShanghai 200237China

co oxidation at ceria surfaces has been studied for decades,and many efforts have been devoted to understanding the effect of surface reduction on the catalytic *** this work,we theoretically studied the co oxidation on the clean and reduced CeO_(2)(111)surfaces using different surface cells to dete rmine the relationships between the reduction degrees and calculated reaction *** is found that the calculated barrier for the direct reaction between co and surface lattice O drastically decreases with the increase of surface reduction *** electronic analysis,we found that the surface reduction can lead to the occurrence of localized electrons at the surface Ce,which affects the charge distribution at surface *** the result,the surface O becomes more negatively charged and therefore more active in reacting with *** work then suggests that the localized 4 f electron reservoir of Ce can act as the"pseudo-anion"at reduced CeO_(2) surfaces to activate surface lattice O for catalytic oxidative reactions.

关键词： co oxidation CeO_(2)(111) Mars-van krevelen mechanism DFT+U Surface reduction

Nanoceria Supported Gold Catalysts for co oxidation

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Chinese Journal of Chemistry 2018年第7期36卷 639-643页

作者： Zhao Jin Yang-Yang Song Xin-Pu Fu Qi-Sheng Song Chun-Jiang Jia Key Laboratory for colloid and interface Chemistry Key Laboratory of Special Aggregated Materials School of Chemistry and Chemical Engineering Shandong University Jinan Shandong 250100 China

Two types of CeO2 nanocubes （average size of 5 and 20 nm, respectively） prepared via the hydrothermal process were selected to load gold species via a deposition-precipitation （DP） method. Various measurements, including X-ray diffraction （XRD）, Raman spectra, high resolution transmission electron microscopy （HRTEM）, in situ diffuse reflectance infrared Fourier transform spectroscopy （in situ DRIFTS）, and temperature-programmed reduction by hydrogen （H2-TPR）, were applied to characterize the catalysts. It is found that the sample with ceria size of 20 nm （Au/CeO2-20） was covered by well dis ersed both Au^3＋ and Au^δ＋（0〈δ〈1）. For the other sample with ceria size of 5 nm （Au/CEO2-5）, Au^3＋ is the dominant gold species. Au/CeO2-20 performed better catalytic activity for co oxidation because of the strong co adsorption of Au^δ＋ in the catalysts. The catalytic activity of Au/CeO2-5 was improved due to the transformation of Au^3＋ to Au^δ＋. Based on the co oxidation and in situ DRIFTS results, Au^δ＋ is likely to play a more important role in catalyzing co oxidation reaction.

关键词： gold catalysts nanoceria co oxidation active species

Size Effect of Gold Sol/γ-Alumina on the Catalytic Activities of co oxidation

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Chinese Journal of Chemistry 2006年第6期24卷 817-821页

作者：王卫华曹更玉 Hefei National Laboratory for Physical Sciences at Microscale Laboratory of Bond Selective Chemistry Department of Chemical Physics University of Science and Technology of China Hefei Anhui 230026 China

The relationship between particle size and catalytic activity of gold nanoparticle catalysts with γ-Al2O3 as support has been investigated. The catalysts were prepared via the gold sol with different particle sizes by micelle method, and their structures were characterized by HRTEM and XRD, respectively. Furthermore, the catalytic activities were tested by co oxidation. Experimental results showed that the catalytic activity became much weaker when gold particles were increased from 3.2 to 6.6 nm. Additionally, the particle size was also a key factor to govern catalytic activity with regard to gold supported on TiO2 prepared by the methods of deposition-precipitation.

关键词： supported catalyst gold sol γ-alumina co oxidation

Dual-template synthesis of defect-rich mesoporous co_(3)O_(4) for low temperature co oxidation

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Chinese Chemical Letters 2023年第7期34卷 368-372页

作者： Shuhua Song Jian Liang Wei Xiao Dong Gu The Institute for Advanced Studies Wuhan UniversityWuhan 430072China college of Chemistry and Molecular Sciences Wuhan UniversityWuhan 430072China

co oxidation is a benchmark in heterogeneous catalysis for evaluation of redox catalysts due to its practical relevance in many applications and the fundamental problems associated with its very high activity at low *** which,co_(3)O_(4) is one of the most active non-precious metal *** crystal planes and cobalt sites are considered to be important for its high catalytic ***,we demonstrate an enhanced co oxidation activity by a defect-rich mesoporous co_(3)O_(4) that prepared by a designed dual-template *** different kinds of silicas are used as hard-templates at the same time,resulting in a defect-rich mesoporous co_(3)O_(4) with a surface area as high as 169 m^(2)/*** catalyst exhibited a very high catalytic activity for low temperature co oxidation with a light-off temperature at -73℃ under the space velocity of 80,000 mL h^(-1)g^(-1)_(cat).Further studies reveal that the high surface area promotes the lattice oxygen mobility,surface rich of co^(2+)species and active oxygen species are crucial for the high catalytic ***,the dual-template approach paves a way towards the design and construction of high-surface-area mesoporous metal oxides for various applications.

关键词： Mesoporous Dual-template co_(3)O_(4) co oxidation Defect