Crystal-facet-dependent activity and N2 yield of Ag/CeO2 catalysts for catalytic oxidation of N, N-Dimethylformamide

Abstract

Shape-controlled CeO2 with different exposed crystal facets, CeO2 nanorods (110) and (100), nanocubes (100) and nano-octahedrons (111), were prepared as supports of Ag and then the catalytic oxidation of N, N-dimethylformamide (DMF) was investigated. Ag/CeO2 nanorod (Ag/r-Ce) catalyst exhibits better dispersion of Ag species due to the abundant oxygen vacancies of CeO2 (110) with outstanding anchoring effect, meanwhile, more Ag-O-Ce interfaces and Ag+ species are achieved because of the strong metal-support interaction and easy migration of oxygen species between Ag and CeO2 (110). Ag/r-Ce catalyst exhibits excellent catalytic activity (T90 =158 °C), 100% yield of CO2 at 240 °C, 80% yield of N2 in the temperature range of 237–400 °C, unexceptionable H2O-resistance, high stability at 240 °C for 120 h. In situ DRIFTS reveals that the dissociation of (O)C-N bond is firstly involved in DMF oxidation, and then the stepwise and repeated dehydrogenation of -N(CH3)2 and the insertion reaction of surface lattice oxygen occurs. Meanwhile the formed -HCO is completely oxidized into CO2 and H2O by surface adsorbed oxygen species and the two adjacent -NH2 species combines into N2.