Oxidative dehydrogenation of methanol at ceria-supported vanadia oligomers

摘要

We study the adsorption and partial oxidation of methanol at a trimeric VOx species supported on ceria, which was found to be the thermodynamically most stable species under slightly reducing conditions. Results for the oxidation of methanol obtained using dispersion-corrected PBE+U and HSE are compared with a metastable monomeric VO2 species. The intrinsic barriers for monomers (103 kJ/mol), trimers (133 kJ/mop, and the pristine surface (136 kJ/mol) are compared with the corresponding values derived from temperature-programmed desorption experiments, i.e. 100, 125, and 150 kJ/mol, respectively. It was found that the VO2 trimer is more active than the pristine ceria (1 1 1) surface due to entropic effects, showing up in a higher pre-exponential factor. However, the VO2 trimer is less active than the monomer due to structural relaxation in the surface O layer of the latter. (C) 2017 Elsevier Inc. All rights reserved.