Direct catalytic conversion of glycerol to liquid-fuel classes over Ir–Re supported on W-doped mesostructured silica

Abstract

Glycerol was converted to liquid fuels through a one-pot process catalyzed by mesostructured Ir–Re–W/SiO2. The reaction was performed over 0.4g of catalyst suspended in an aqueous solution of glycerol (4.72mmol/ml) at 553K under a hydrogen pressure of 6.0MPa for 50h. A hydrocarbon-enriched organic phase was self-separated from the aqueous solution after the reaction. The total yield of oil products was greater than 40%, and the selectivity toward hydrocarbons was approximately 90%. The conversion proceeds through a complicated mechanism that involves a CC coupling reaction and hydrodeoxygenation. Doped tungsten oxide species in a silica matrix are active acidic sites for acid-catalyzed dehydration. Supported iridium species are catalytic active sites for hydrodeoxygenation and CC coupling reactions. The evolution of their chemical states during the catalytic process was detected by X-ray photoelectron spectroscopy. Rhenium species are important co-catalysts for iridium species. These active catalytic species work together to achieve the direct conversion of glycerol in aqueous solution to liquid fuels under a hydrogen atmosphere.