Glycerol liquid phase conversion over monometallic and bimetallic catalysts: Effect of metal, support type and reaction temperatures

Glycerol liquid conversion under catalytic aqueous steam reforming conditions was studied. For this purpose monometallic Ni and Pt and bimetallic PtNi catalysts supported on γ-Al2O3 and La2O3-modified γ-Al2O3 were employed. Activity measurements indicated that among the tested catalysts, the PtNi catalysts were, in general, the most active, whereas the Ni catalysts suffered from increasing deactivation as the temperature increased. In addition, glycerol conversion was mainly due to the production of intermediate oxygenated hydrocarbons at the reaction conditions investigated. In general, the presence of La2O3 improved this catalytic behaviour toward lighter gaseous products. The characterisation results, together with the activity results, suggested that the high activity of the PtNi catalysts can be associated with limited metal dispersion, the formation of metal Pt–Ni alloy and the spill-over phenomenon. The last two effects hindered carbon deposition. Furthermore, the deactivation of the Ni catalysts was also associated with the oxidation of metallic Ni phases in the presence of adsorbed H2O.

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► Conversion was due to the formation of intermediate liquid oxygenated hydrocarbons at different temperatures.
► Among the liquid oxygenated hydrocarbons, 1,2-propylene glycol was the main product.
► Bimetallic catalysts showed good catalytic activity related with low dispersion of metallic active sites, Pt–Ni alloy formation and H2 spill-over.
► La2O3 addition improved the H2 yield by increasing Ni0 dispersion in Ni/γ-AM catalyst and surface exposure of Ni in PtNi/γ-AM catalyst.
► Ni catalysts deactivation observed was due to oxidation by water.