Clarification of copper species over Cu-SAPO-34 catalyst by DRIFTS and DFT study of CO adsorption  

作　　者：Zheng Qu Ying Li Shouying Huang Pengzhen Chen Xinbin Ma 

机构地区：[1]Key Laboratory for Green Chemical Technology of Ministry of Education,Collaborative Innovation Center of Chemical Science and Engineering,School of Chemical Engineering and Technology,Tianjin University,Tianjin 300072,China

出　　处：《Science China Chemistry》2017年第7期912-919,共8页中国科学（化学英文版）

基　　金：supported by the National Natural Science Foundation of China(21325626,21406120)

摘　　要：In this work, the nature, location and evolution of Cu+ ions in Cu-SAPO-34 are investigated by diffuse reflectance infrared Fourier transform spectrum(DRIFTS) of CO adsorption and density functional theory(DFT) calculation. By combination with DFT results, characteristic Cu+–CO bands located at 2154 and 2136 cm.1 are attributed to CO adsorbed on Cu+ ions located at sites I(in the plane of six-membered ring connected to the large cages) and site II(in the eight-membered ring cages near the tilted four membered ring) in the framework of H-SAPO-34 zeolite. Subsequently, both the influences of Cu loading and preparation method are considered and discussed. By varying the Cu loading, the site-occupation preference of Cu+ ions on site I is confirmed,especially at low Cu loadings. Through elevating the desorption temperature, migration of Cu+ ions is revealed because of the adsorption-induced effect. Furthermore, a facile and more efficient approach to introduce Cu+ ions into CHA zeolite, compared with solid-state ion exchange with CuCl and conventional ion exchange in aqueous solution, and the different preparation methods also result in different occupations of Cu+ ions.In this work, the nature, location and evolution of Cu＋ ions in Cu-SAPO-34 are investigated by diffuse reflectance infrared Fourier transform spectrum（DRIFTS） of CO adsorption and density functional theory（DFT） calculation. By combination with DFT results, characteristic Cu＋–CO bands located at 2154 and 2136 cm.1 are attributed to CO adsorbed on Cu＋ ions located at sites I（in the plane of six-membered ring connected to the large cages） and site II（in the eight-membered ring cages near the tilted four membered ring） in the framework of H-SAPO-34 zeolite. Subsequently, both the influences of Cu loading and preparation method are considered and discussed. By varying the Cu loading, the site-occupation preference of Cu＋ ions on site I is confirmed,especially at low Cu loadings. Through elevating the desorption temperature, migration of Cu＋ ions is revealed because of the adsorption-induced effect. Furthermore, a facile and more efficient approach to introduce Cu＋ ions into CHA zeolite, compared with solid-state ion exchange with CuCl and conventional ion exchange in aqueous solution, and the different preparation methods also result in different occupations of Cu＋ ions.

关 键 词：Cu-SAPO-34 CO adsorption DRIFTS DFT 

分 类 号：O643.36[理学—物理化学] O647.3[理学—化学]