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

A salt of ruthenium-containing polyoxomolybdate anion ([Ru2Mo14O50]10− or [Ru2Mo14O52]14−; Ru2Mo14) was synthesized by mixing ruthenium chloride and sodium molybdate in a buffer solution (acetic acid–ammonium acetate) at pH 5. The polyanion, Ru2Mo14, was loaded on a silica carrier chemically modified with a silane coupling agent having a 1,2-diaminoethyl group (DAPS–SiO2). X-ray diffraction, FT-IR and surface area measurements revealed that Ru2Mo14 was highly dispersed on DAPS–SiO2 up to 20 wt.% loading. The highly dispersed Ru2Mo14 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 Ru2Mo14 and ruthenium catalyst supported on a SiO2 carrier.