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

• 来源期刊: 中国科学:化学（英文版）
• 年，卷（期）: 2017,（7）
• 页码范围: 912-919
• 页数: 8页
• 语种: 英文
• DOI: 10.1007/s11426-016-9063-2

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 2136cm 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 ofCu+ 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 CuC1 and conventional ion exchange in aqueous solution,and the different preparation methods also result in different occupations of Cu+ ions.