Glycerol hydrogenolysis to 1, 2 propanediol over Ru/C catalyst

Abstract

Optimal experimental conditions for catalytic conversion of glycerol to 1,2 propanediol over catalyst Ru/C are investigated. Results indicate that glycerol hydrogenolysis is the result of two reaction stages: dehydration to acetol and hydrogenation to 1,2 propanediol. Use of a cationic exchange resin improves the dehydration stage, providing higher conversion and selectivity to 1,2 propanediol. Division of the reaction time into a dehydration period (under a nitrogen atmospheric pressure) and a hydrogenation period (under a hydrogen atmosphere of 60 bar) is essayed. This sequential stage reaction process provides lower glycerol conversion but increases the selectivity ratio between 1,2 propanediol and the main liquid by-product, ethylenglycol. The influence of two relevant variables in this process, H2/glycerol ratio and initial glycerol concentration, is analysed. Increasing the H2/glycerol ratio increases glycerol conversion, although it also causes higher production of unfavourable ethylenglycol. Ethylenglycol production is reduced when the glycerol concentration increases. A balance between conversion and selectivity is necessary in order to select optimal reaction conditions.