Effects of Anion Substitution in (Mo,V)(5)O-14 on Catalytic Performance in Selective Propene Oxidation to Acrolein

摘要

Molybdenum-based mixed oxides represent well-known model catalysts for the selective oxidation of light alkenes. Here, the anion lattice of (Mo,V)(5)O-14 was for the first time modified by substituting oxygen ions with nitrogen ions. Investigations by XRD analysis, X-ray absorption spectroscopy, and FTIR spectroscopy revealed that the incorporation of nitrogen in the structure of Mo5O14 proceeded without changing the average valence of metal centers. Additionally, impedance spectroscopy confirmed the formation of oxygen vacancies. Significant changes in conductivities remained after the removal of nitrogen. Temperature-programmed reduction measurements were performed to investigate oxygen mobility. The enhanced reducibility of oxide nitrides correlated with the increased conductivity. Catalytic performance in selective propene oxidation was determined by online mass spectrometry und gas chromatography at different temperatures. Selectivity towards acrolein increased with increasing conductivity whereas the formation of total oxidation products COx decreased.