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Detrimental role of residual surface acid ions on ozone decomposition over Ce-modified γ-MnO2under humid conditions

查看全文 作　　者：Xiaotong [1,3]Li;Jinzhu [1,2,3]Ma;Changbin [1,3]Zhang;Runduo [4]Zhang;Hong [1,2,3]He 高影响力作者 机构地区：[1]State Key Joint Laboratory of Environment Simulation and Pollution Control,Research Center for Eco-Environmental Sciences,Chinese Academy of Sciences,Beijing 100085,China;[2]Center for Excellence in Regional Atmospheric Environment,Institute of Urban Environment,Chinese Academy of Sciences,Xiamen 361021,China;[3]University of Chinese Academy of Sciences,Beijing 100049,China;[4]State Key Laboratory of Chemical Resource Engineering,Beijing University of Chemical Technology,Beijing 100029,China高影响力机构 出　　处：《Journal of Environmental Sciences》索引2020年第32卷第5期,共11页高影响力期刊 基　　金：supported by the National Key R&D Program of China(Nos.2016YFC0207104 and 2017YFC0211802);the National Natural Science Foundation of China(NSFC)(No.21876191);the Youth Innovation Promotion Association,CAS(No.2017064) 摘　　要：In the study,the catalyst precursors of Ce-modifiedγ-MnO2 were washed with deionized water until the pH value of the supernatant was 1,2,4 and 7,and the obtained catalysts were named accordingly.Under space velocity of 300,000 hr-1,the ozone conversion over the pH=7 catalyst under dry conditions and relative humidity of 65%over a period of 6 hr was 100%and 96%,respectively.However,the ozone decomposition activity of the pH=2 and 4 catalysts distinctly decreased under relative humidity of 65%compared to that under dry conditions.Detailed physical and chemical characterization demonstrated that the residual sulfate ions on the pH=2 and 4 catalysts decreased their hydrophobicity and then restrained humid ozone decomposition activity.The pH=2 and 4 catalysts had inferior resistance to high space velocity under dry conditions,because the residual sulfate ion on their surface reduced their adsorption capacity for ozone molecules and increased their apparent activation energies,which was proved by temperature programmed desorption of O2 and kinetic experiments.Long-term activity testing,X-ray photoelectron spectroscopy and density functional theory calculations revealed that there were two kinds of oxygen vacancies on the manganese dioxide catalysts,one of which more easily adsorbed oxygen species and then became deactivated.This study revealed the detrimental effect of surface acid ions on the activity of catalysts under humid and dry atmospheres,and provided guidance for the development of highly efficient catalysts for ozone decomposition. 关 键 词：Ozone decomposition Manganese dioxide Surface acid ions Moisture-resistant property Oxygen vacancy
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