Aqueous-phase reforming of glycerol using Ni–Cu catalysts prepared from hydrotalcite-like precursors

Abstract

Ni–Cu catalysts derived from hydrotalcite-like compounds were prepared with 20 wt% of NiO and 0, 5 and 10 wt% of CuO, and evaluated in the aqueous-phase reforming of glycerol. The catalysts were characterized by chemical composition, textural analysis, crystalline structure, reducibility and acidity. The reaction was performed in a continuous flow reactor with a solution of 10 vol% glycerol, at 250 °C/35 atm and 270 °C/50 atm. The maximum glycerol conversion at 250 °C/35 atm was 70% and total conversion of glycerol was achieved at 270 °C/50 atm with Cu-containing catalysts. In the gas phase, the H₂ selectivity was around 40% and CO selectivity was very low at 250 °C/35 atm. The addition of Cu decreased the CH₄ formation. The main products formed in the liquid phase were acetol and lactic acid and a small quantity of propanoic acid. The Cu-containing catalysts showed higher formation of acetol, which was correlated with their higher acidity. Characterization of the spent catalysts revealed a sintering of the metal particles, although no deactivation was observed during 6 h of reaction.