Regioselective hydrogenolysis of alga-derived squalane over silica-supported ruthenium-vanadium catalyst

Addition effect of 2nd metal to Ru catalysts in hydrogenolysis of squalane was investigated. Addition of V gave lower methane selectivity and higher C14-C16 selectivity and the effect was the most remarkable over SiO2 support. However, addition of V decreased the catalyst activity and increased the deposited amount of carbonaceous species. From hydrogenolysis of n-hexadecane, addition of V suppressed the formation of methane via terminal C-C bond dissociation, but the formation via fragmentation was not suppressed. Ru and V valences in Ru-VOx/SiO2 (V/Ru = 0.25) after reduction were 0 and +III, respectively. The size of Ru particles was about 4 nm from XRD even in changing V/Ru ratio. H-2 chemisorption showed that V covered the Ru particles and reduced the size of Ru ensemble. In reuse test, it was difficult to retain the catalyst performance for hydrogenolysis of squalane even with various treatments of the recovered catalyst such as washing with n-hexane, heating in N-2 flow or calcination in air. From XAS analysis, the contact of Ru particles with air caused the aggregation of Ru metal especially when calcined in air.