Modified hydrotalcites as precursors for catalysts effective in the hydrogenolysis of glycerol to 1,2-propanediol

A series of hydrotalcite-like materials containing Al, Cu and one other bivalent metal, selected from the group Ni, Fe, Co and Zn, were prepared in the frame of this study. These hydrotalcite-like structures were used as precursors of the catalysts for the hydrogenolysis of glycerol. The hydrotalcites were converted to active forms of catalysts by calcination at a programmed temperature, increasing with the speed of 2 °C/min, up to 350 °C and reduction by hydrogen at 350 °C and 7 MPa. The catalysts were characterized by XRD, TGA, TPR, TPD, HRTEM, Hg porosity and N2 physisorption. The catalyst containing Zn exhibited the highest activity and selectivity to 1,2-propanediol in the hydrogenolysis of glycerol despite the fact that it had lowest internal surface area from all the catalysts studied. Its activity was attributed to its specific pore volume distribution with highest fraction of wider macropores in the range between 1 and 10 µm, remarkably distinguishing this catalyst from all the other catalysts studied.