Hydrogenolysis of glycerol to 1,2-propanediol over nano-fibrous Ag-OMS-2 catalysts

Abstract

Increasing demand for biodiesel production would lead to tremendous supply of glycerol as a coproduct, which is almost 10% by weight. Therefore, utilization of bioglycerol into valuable chemicals is timely to reduce the cost of biodiesel. Both 1,2- and 1,3-propanediols are very useful chemicals which can be produced from glycerol. This paper describes a novel process for selective hydrogenolysis of glycerol to 1,2-propanediol over silver incorporated octahedral molecular sieve (OMS-2) catalyst. Also, the current work describes the use of silver as the catalyst for the first time for hydrogenolysis of glycerol. Both batch and continuous mode of operations have been studied to determine the stability of the catalyst. Different loadings (10–30% w/w) of Ag were incorporated in OMS-2 by the precipitation method and used in the reaction. Thirty % w/w Ag-OMS-2 was the best catalyst. It was characterized by various techniques such as SEM, TGA, XRD, N₂ adsorption–desorption, EDAX, TPD-TPR, and FTIR. It is a nano fibrous crystalline material. This Article reports a comprehensive account of this catalytic process.The initial studies were carried out in a batch reactor to optimize the reaction parameters. High conversion of glycerol (about 65–70%) with about 90% selectivity toward 1,2-propanediol was obtained within 8 h under hydrogen pressure. The time-on-stream (TOS) analysis studies were conducted in a fixed bed reactor up to 150 h, which demonstrated that the catalyst was stable and the process has a potential for commercial exploitation.