Oxidative dehydrogenation of methanol over a ruthenium-containing polyoxomolybdate supported on metal oxides chemically modified with silane coupling agent

摘要

A salt of ruthenium-containing polyoxomolybdate anion ([Ru_2Mo_(14)O_(50)]~(10-) or [Ru_2Mo_(14)O_(52)]~(14-);Ru_2Mo_(14)) was synthesized by mixing ruthenium chloride and sodium molybdate in a buffer solution (acetic acid-ammonium acetate) at pH 5.The polyanion,Ru_2Mo_(14),was loaded on a silica carrier chemically modified with a silane coupling agent having a 1,2-diaminoethyl group (DAPS-SiO_2).X-ray diffraction,FT-IR and surface area measurements revealed that Ru_2Mo_(14) was highly dispersed on DAPS-SiO_2 up to 20 wt.% loading.The highly dispersed Ru_2Mo_(14) exhibited a high level of activity for oxidative dehydrogenation of methanol to formaldehyde with a high selectivity,whereas combustion of methanol occurred on the bulky salt of Ru_2Mo_(14) and ruthenium catalyst supported on a SiO_2 carrier.