Vapor-Phase Hydrogenolysis of Glycerol to 1,2-Propanediol over Cu/Al2O3 Catalyst at Ambient Hydrogen Pressure

Abstract

In this paper, we report that the hydrogenolysis of glycerol can be carried out at atmospheric pressure and low temperature with high selectivity to 1,2-propanediol (1,2-PDO) over reduced copper catalyst. The vapor-phase reaction was carried out over the copper-based catalysts supported on alumina at ambient pressure, and the effects of temperature, space time, and H2 molar fraction in the feed were analyzed. The textural and structural characteristics of the catalysts with increasing copper loading were determined by N2 sorptometry (BET), inductively coupled plasma-atomic spectroscopy (ICP-AES), powder X-ray diffraction (PXRD), temperature-programmed reduction (TPR), and N2O chemisorption (metallic area). On the basis of both characterization and activity results, it was possible to conclude that the hydrogenolysis of glycerol to 1,2-propanediol in vapor phase at atmospheric pressure over copper-based catalysts is a structure sensitive reaction. Activity results suggests that the most probable pathway for the glycerol conversion into 1,2-propanediol under the employed conditions is glycerol is dehydration to hydroxyacetone (acetol), followed by its hydrogenation into 1,2-propanediol. Complete glycerol conversion and a selectivity of 60% to 1,2-propanediol was achieved, using a catalyst with 15 wt % CuO at 200°C, H2 molar fraction of 61%, and atmospheric pressure.