Selective hydrogenolysis of glycerol to 1,2-propanediol over highly active copper-magnesia catalysts: reaction parameter, catalyst stability and mechanism study

BACKGROUNDThe surplus amount of glycerol (>1 million tons per year) from the biodiesel industry has received much attention in recent years for the production of alternative chemicals. The performance of x%Cu/MgO (x=5-50%) catalysts was investigated for selective hydrogenolysis of glycerol to 1,2-propanediol (1,2-PDO). The primary emphasis was given to the optimization of reaction parameters, reaction mechanism and catalyst stability. RESULTSThe 35%Cu/MgO catalyst exhibited the maximum glycerol conversion of 96.6% with 92.6% selectivity to 1,2-PDO at 210 degrees C and 4.5 MPa H-2 pressure. The high catalytic activity was attributed to the presence of bifunctional acidic-basic sites, and the synergetic interaction between copper nanoparticles and MgO support. To understand the reaction mechanism, the role of intermediates (1,2-PDO, acetol, ethylene glycol) was investigated. Catalytic stability and reusability experiments were performed by repeating the reaction three times. The results of characterization of fresh and used catalysts demonstrated negligible deactivation of 35%Cu/MgO catalyst after successive reuse. CONCLUSIONCu/MgO catalyst played a significant role in enhancing the hydrogenolysis activity. The results demonstrated that glycerol conversion was rapidly increased with increasing reaction temperature, pressure and copper metal loading. The conversion of glycerol to 1,2-PDO followed the dehydration-hydrogenation pathway and hydrogenolysis of C-C bonds was almost negligible. (c) 2015 Society of Chemical Industry