Coupling of glycerol-APR and in situ hydrodeoxygenation of fatty acid to produce hydrocarbons

Abstract

Glycerol valorization by coupling APR to yield hydrogen with hydrogenation of a model compound as tandem reactions is approached using Pt-Ni/Al2O3 as efficient catalyst. Oleic acid is used as a C18 fatty acid model compound for in situ hydrogenation reaction. The combination of the two catalytic transformations to a single tandem process appears particularly interesting since this protocol reduces the number of synthetic steps towards the target compound and avoids external hydrogen supply. Glycerol reforming is carried out in a catalytic fixed bed batch reactor under subcritical water condition between 175 and 275°C (2–6.21MPa as autogenous pressure). The coupled reactions were carried out using 1wt %of catalyst, adding oleic acid to the mixture of water/glycerol and without any external hydrogen supply. In APR, maximum glycerol conversion of 80.3% was achieved using Pt-Ni/Al2O3 catalyst at 200°C with H2-selectivity close to 80% and CO formation below to 3.7%. In the coupled reactions, no hydrogen is observed in the gas-off, which is associated to the hydrogen consumption by oleic acid at 275°C; reaching a hydrogenation conversion value close to 91.3% and deoxygenation conversion of 32% giving a C17 paraffinic like-hydrocarbon.