Selective Hydrogenolysis of Glycerol to 1,2-Propylene Glycol on Ultrafine Copper Particles

Abstract

Hydrogenolysis of glycerol to 1,2-propylene glycol at 200°C in the presence of Cu/Al2O3 catalysts prepared by coprecipitation from copper nitrate and aluminum nitrate using NaOH and NH4OH has been studied. The kinetics of the reaction is described by the first-order rate law. It has been found that the selectivity for the target product for all catalyst samples is 98% and the activity of the catalysts depends on their synthesis conditions. By using X-ray diffraction analysis, transmission electron microscopy, energy dispersive X-ray analysis, and X-ray photoelectron spectroscopy, it has been revealed that the active phase of Cu/Al2O3 samples is made of particles with an average size of 20 to 140 nm, whose surface consisted of CuO and Cu2O. The catalysts with different particle sizes the active phase but close chemical composition exhibits comparable activity (67.5 ± 5 h–1mol—1). This finding indicates that the hydrogenolysis reaction run in the presence of Cu/Al2O3 is not structure-responsive. A decrease in concentration of the Cu2O phase of the catalyst leads to a decrease in the hydrogenolysis rate, thereby this indicating a higher activity of the Cu2O phase in comparison with the CuO phase.