Role of surface oxygen species of mesoporous CeCu oxide catalyst in OVOCs catalytic combustion

Abstract

Mesoporous CeO2 and CeCu-composite oxide catalysts (with nCe/nCu of 2, 3, and 4) were prepared by hard-template methods using KIT-6 as template, and used to study the influence of nCe/nCu molar ratios on the surface oxygen species and catalytic activity of CeCu-HTx oxide catalysts. The surface oxygen species were studied by XPS, LRS, FT-IR, and O2-TPD, and the catalytic performance were tested in OVOCs catalytic combustion in air. The results showed that CeCu-HTx catalysts having more developed mesoporous structure and larger specific surface area than Ce-HT catalyst. And the CuO effectively dissolved into CeO2 lattice to form CeCu oxide solid solution and produce abundant surface adsorbed oxygen species in CeCu-HTx catalysts (prominently for CeCe-HT3), as well as to generate oxygen vacancies that enhanced the O2 molecules activation and oxygen mobility of catalysts. While, the CeO2 species facilitated formation of surface adsorbed OH group that can change into adsorbed oxygen species at high temperature. The CeCu-HT3 exhibited higher catalytic activity than CeCu-HT4, CeCu-HT2 and Ce-HT for ethyl acetate catalytic combustion, showing positive relationship with the surface adsorbed oxygen content and oxygen mobility. The CeCu-HT3 also showed high stability for ethyl acetate catalytic combustion, and good catalytic activity for propyl acetate, methyl acetate, and butyl acetate catalytic combustion.