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deactivation mechanism of CaO in a flow type dimethyl carbonate synthesis process

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Resources Chemicals and Materials 2024年第1期3卷 46-53页

作者： Jianing Liu Peng Zheng Zizhen Yan Yuxin Wang Zhanguo Zhang Guangwen Xu Jianjun Guo Lei Shi Key Laboratory on Resources Chemicals and Materials of Ministry of Education Shenyang University of Chemical TechnologyShenyang 110142China Shinghwa Advanced Material Group Co. ltdDongying 257000China Institute of Industrial Chemistry and Energy Technology Shenyang University of Chemical TechnologyShenyang 110142China

It is well known that calcium oxide (CaO) has better catalytic efficiency than most heterogeneous catalysts in many transesterification reactions. However, the gradual deactivation problem prevents its large-scale application in industry. In this paper, the deactivation mechanism of CaO in a fixed-bed reactor is investigated based on the transesterification reaction of propylene carbonate and methanol. The leaching amount of CaO during the reaction was estimated by the concentration of Ca in the products. The pretreated and recovered catalysts were characterized by FT-IR, XRD, TG-MS and SEM-EDS. It is evident from experiments and characterization that the deactivation process of CaO is accompanied by the leaching of calcium species and the generation of CaCO3, which are also verified by DFT calculations. At high temperature and high weight hourly space velocity, the deactivation was attributed to the formation of dense CaCO3 shell, which prevents the contact between the feedstock and the active species inside.

关键词： Calcium oxide Dimethyl carbonate deactivation mechanism Fixed-bed reactor Transesterification

Lean methane combustion over zeolite-supported Pd catalysts:Structure-performance relationship and deactivation mechanism

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Journal of Environmental Sciences 2024年第11期145卷 128-138页

作者： Xingyu Liu Jingkun Chen Bowen Han Renna Li Le Shi Zhongbiao Wu Xiaole Weng Key Laboratory of Environment Remediation and Ecological Health Ministry of EducationCollege of Environmental and Resource SciencesZhejiang UniversityHangzhou 310058China ZJU-Hangzhou Global Scientific and Technological Innovation Center Zhejiang UniversityHangzhou 311200China Zhejiang Provincial Engineering Research Centre of Industrial Boiler&Furnace Flue Gas Pollution Control Hangzhou 310058China

Zeolites are a promising support for Pd catalysts in leanmethane(CH_(4))***,three types of zeolites(H-MOR,H-ZSM-5 and H-Y)were selected to estimate their structural effects and deactivation mechanisms in CH_(4)*** show that variations in zeolite structure and surface acidity led to distinct changes in Pd ***/H-MOR with external high-dispersing Pd nanoparticles exhibited the best apparent activity,with activation energy(Ea)at 73 kJ/mol,while Pd/H-ZSM-5 displayed the highest turnover frequency(TOF)at 19.6×10^(−3)sec^(−1),presumably owing to its large particles with more step sites providing active sites in one particle for CH_(4)***/H-Y with dispersed PdO within pore channels and/or Pd2+ions on ion-exchange sites yielded the lowest apparent activity and ***,Pd/H-MOR and Pd/H-ZSM-5 were both stable under a dry condition,but introducing 3 vol.%H_(2)O caused the CH_(4)conversion rate on Pd/H-MOR drop from 100%to 63%and that on Pd/H-ZSM-5 decreased remarkably from 82%to 36%.The former was shown to originate fromzeolite structural dealumination,and the latter principally owed to Pd aggregation and the loss of active PdO.

关键词： Methane combustion Pd catalysts Zeolite Structure-performance relationship deactivation mechanism

Reconstruction of Cu-ZnO catalyst by organic acid and deactivation mechanism in liquid-phase hydrogenation of dimethyl succinate to 1,4-butanediol

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Frontiers of Chemical Science and Engineering 2023年第9期17卷 1311-1319页

作者： Fan Sun Huijiang Huang Wei Liu Lu Wang Yan Xu Yujun Zhao Key Laboratory for Green Chemical Technology of Ministry of Education Collaborative Innovation Center of Chemical Science and EngineeringSchool of Chemical Engineering and TechnologyTianjin UniversityTianjin300072China

A reconstructed Cu-ZnO catalyst with improved stability was fabricated by organic acid treatment method for the liquid-phase hydrogenation of dimethyl succinate to 1,*** to the characterization results of the fresh Cu-ZnO and reconstructed Cu-ZnO,three different forms of ZnO were suggested to be presented on the catalysts:ZnO having strong interaction with Cu species,ZnO that weakly interacted with Cu species and isolated *** first form of ZnO was believed to be beneficial to the formation of efficient active site Cu^(+),while the latter two forms of ZnO took the main responsibility for the deactivation of Cu-ZnO catalysts in the liquid-phase hydrogenation of *** reconstruction of the Cu-ZnO catalyst by the organic acid treatment method resulted in a new Cu-ZnO catalyst with more Cu^(+)and less ZnO species that leads to ***,the deactivation mechanism of Cu-ZnO catalysts in liquid-phase diester hydrogenation in continuous flow system was proposed:the deposition of the polyesters on the catalysts via transesterification catalyzed by weakly interacted ZnO and isolated ZnO leads to the *** results provided meaningful instructions for designing highly efficient Cu-Zn catalysts for similar ester hydrogenation systems.

关键词： liquid phase hydgonenation Cu-ZnO deactivation mechanism 1,4-butanediol diester

Recent progress in the deactivation mechanism of zeolite catalysts in methanol to olefins

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Science China Chemistry 2024年第12期67卷 3934-3943页

作者： Sheng Fan Han Wang Sen Wang Mei Dong Weibin Fan State Key Laboratory of Coal Conversion Institute of Coal ChemistryChinese Academy of SciencesTaiyuan 030001China University of Chinese Academy of Sciences Beijing 100049China

Methanol to olefins(MTO)as an important reaction in C1 chemistry can effectively transform non-petroleum carbon resources into value-added *** have been widely used as MTO ***,they usually suffer from a rapid deactivation due to bulky coke species production,and thus require continuous regenerations in industrial *** key to design and develop highly stable zeolite catalysts for MTO process is to unravel the deactivation mechanism and clarify the structure–performance relationship of ***,in this mini-review,we investigate the critical intermediate species inducing zeolite deactivation and analyze the formation and evolution pathways of polycyclic aromatic hydrocarbons(PAHs)that are the precursors of carbonaceous *** addition,some methods to alleviate the coking mainly including acid regulation,morphology modification and process optimization,are also summarized.

关键词： methanol to olefins zeolites deactivation mechanism polycyclic aromatic hydrocarbons

deactivation mechanism of acetone to isobutene conversion over Y/Beta catalyst

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Chinese Journal of Catalysis 2024年第9期64卷 133-142页

作者： Chang Wang Tingting Yan Weili Dai School of Materials Science and Engineering Nankai UniversityTianjin 300350China College of Science Civil Aviation University of ChinaTianjin 300300China

The conversion of acetone derived from biomass to isobutene has attracted extensive *** comparison with Brønsted acidic catalyst,Lewis acidic catalyst could exhibit a better catalytic performance with a higher isobutene ***,the catalyst stability remains a key problem for the long-running acetone conversion and the reasons for catalyst deactivation are poorly understood up to ***,the deactivation mechanism of Lewis acidic Y/Beta catalyst during the acetone to isobutene conversion was investigated by various characterization techniques,including acetone-temperature-programmed surface reaction,gas chromatography-mass spectrometry,in situ ultraviolet-visible,and ^(13)C cross polarization magic angle spinning nuclear magnetic resonance spectroscopy.A successive aldol condensation and cyclization were observed as the main side-reactions during the acetone conversion at Lewis acidic Y *** comparison with the low reaction temperature,a rapid formation and accumulation of the larger cyclic unsaturated aldehydes/ketones and aromatics could be observed,and which could strongly adsorb on the Lewis acidic sites,and thus cause the catalyst deactivation *** a simple calcination,the coke deposits could be easily removed and the catalytic activity could be well restored.

关键词： deactivation mechanism Acetone to isobutene Lewis acid sites Y/Beta Spectroscopy

Epidemic Spread in Networks Induced by deactivation mechanism

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Communications in Theoretical Physics 2008年第5期49卷 1357-1360页

作者： YU Xiao-Ling WU Xiao ZHANG Duan-Ming LI Zhi-Hao LIANG Fang WANG Xiao-Yu Department of Physics Huazhong University of Science and Technology Wuhan 430074 China

We have studied the topology and epidemic spreading behaviors on the networks in which deactivation mechanism and long-rang connection are coexisted. By means of numerical simulation, we find that the clustering coefficient C and the Pearson correlation coefficient r decrease with increasing long-range connection μ and the topological state of the network changes into that of BA model at the end （when μ = 1）. For the Susceptible-Infect-Susceptible model of epidemics, the epidemic threshold can reach maximum value at μ = 0.4 and presents two different variable states around μ= 0.4.

关键词： epidemic threshold deactivation mechanism long-rang connection

deactivation mechanisms and anti-deactivation strategies of molecular sieve catalysts for NO_(x)reduction

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Chinese Chemical Letters 2024年第3期35卷 8-18页

作者： Fuli Wang Penglu Wang Jin Zhang Dengchao Peng Mengmeng Wei Dengsong Zhang School of Environmental and Chemical Engineering State Key Laboratory of Advanced Special SteelInternational Joint Laboratory of Catalytic ChemistryCollege of SciencesShanghai UniversityShanghai 200444China

Molecular sieve catalysts,owing to their unique chemical properties,are widely used as catalysts among various catalytic *** Br?nsted acid sites in molecular sieve catalysts usually enable active components to disperse well on the catalyst surface,and help to adsorb a large number of gas molecules to achieve maximum catalytic ***,a variety of molecular sieve catalysts have been developed and used in the selective catalytic reduction of NO_(x)by NH_(3)(NH_(3)-SCR).For example,Cu molecular sieve catalysts such as Cu-SSZ-13 and Cu-SAPO-34 with wide temperature windows and stable structure are considered and applied as commercial catalysts for NO_(x)removal in diesel vehicles for a long *** molecular sieve catalysts possess many advantages,they still cannot avoid the serious deactivation caused by various factors in practical *** this review,reasons leading to the deactivation of molecular sieve catalysts for NO_(x)reduction in actual working conditions were *** deactivation mechanisms of molecular sieve catalysts for NO_(x)reduction were analyzed and the corresponding anti-deactivation strategies were ***,challenges and prospects of molecular sieve catalysts for NO_(x)reduction were also proposed.

关键词： Environmental catalysis NO_(x) reduction Molecular sieve catalysts deactivation mechanism Anti-deactivation

Recent advances in catalytic decomposition of ozone

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Journal of Environmental Sciences 2020年第8期32卷 14-31页

作者： Xiaotong Li Jinzhu Ma Hong He State Key Joint Laboratory of Environment Simulation and Pollution Control Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China Center for Excellence in Regional Atmospheric Environment Institute of Urban EnvironmentChinese Academy of SciencesXiamen 361021China University of Chinese Academy of Sciences Beijing 100049China

Ozone(O3),as a harmful air pollutant,has been of wide ***,efficient,and economical O3 removal methods urgently need to be *** decomposition is the most promising method for O3 removal,especially at room temperature or even subzero *** efforts have been made to develop high-efficiency catalysts for O3 decomposition that can operate at low temperatures,high space velocity and high ***,this review describes the general reaction mechanism of O3 decomposition on noble metal and transition metal oxide ***,progress on the O3 decomposition performance of various catalysts in the past 30 years is summarized in *** main focus is the O3 decomposition performance of manganese oxides,which are divided into supported manganese oxides and non-supported manganese *** to improve the activity,stability,and humidity resistance of manganese oxide catalysts for O3 decomposition are also *** deactivation mechanisms of manganese oxides under dry and humid conditions are *** O3 decomposition performance of monolithic catalysts is also summarized from the perspective of industrial ***,the future development directions and prospects of O3 catalytic decomposition technology are put forward.

关键词： Ozone Catalysis Manganese oxides deactivation mechanism

Enhanced recycling performance of bimetallic Ir-Re/SiO_(2) catalyst by amberlyst-15 for glycerol hydrogenolysis

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Chinese Journal of Chemical Engineering 2022年第5期35卷 171-181页

作者： Xin Ren Li Leng Yueqiang Cao Jing Zhang Xuezhi Duan Xueqing Gong Jinghong Zhou Xinggui Zhou State Key Laboratory of Chemical Engineering East China University of Science and TechnologyShanghai 200237China Key Laboratory for Advanced Materials Centre for Computational Chemistry and Research Institute of Industrial CatalysisEast China University of Science and TechnologyShanghai 200237China

Recycling performance of heterogeneous catalysts is of crucial importance especially for a batch reaction *** this work,we demonstrate a strategy for enhancing recycling performance of Ir-Re/SiO_(2) catalyst synergized with amberlyst-15 in glycerol hydrogenolysis to produce 1,*** characterization results reveal that the Re sites in the Ir-Re/SiO_(2) catalyst undergo irreversible segregation and *** hinder the formation of active ReAOH species and thus contribute to a complete and irreversible ***,the introduction of amberlyst-15 into the reactant mixture can restrain the oxidation process of Re sites and favor the formation of ReAOH species,and thus significantly enhance the catalytic recycling *** results demonstrated here could guide the development of excellent bimetallic catalysts with the desirable recycling performances for the reaction.

关键词： Glycerol hydrogenolysis Ir-Re/SiO_(2)catalyst deactivation mechanism Recycling performance Amberlyst-15 promoter