Liquid-phase glycerol hydrogenolysis to 1,2-propanediol under nitrogen pressure using 2-propanol as hydrogen source

2-Propanol was studied as a hydrogen donor molecule in the transfer hydrogenation process to selectively convert glycerol into 1,2-propanediol under N-2 pressure and using Ni or/and Cu supported on Al2O3 catalysts. The results were compared to those obtained under the same operating conditions but under H-2 pressure. The results of the activity tests and catalyst characterization techniques (N-2-physisorption, H-2-chemisorption, TPD of NH3, TPR. TPO and XPS) suggest that glycerol hydrogenolysis to yield 1,2-propanediol occurred through a different mechanism regarding the origin of the hydrogen species. When atomic hydrogen came from dissolved molecular hydrogen dissociation, glycerol was first dehydrated to acetol and then hydrogenated to 1,2-propanediol. On the other hand, when the hydrogen atoms were produced from 2-propanol dehydrogenation, glycerol was directly converted to 1,2-propanediol through intermediate alkoxide formation. (C) 2011 Elsevier Inc. All rights reserved.