Aqueous-phase deoxygenation of glycerol to 1,3-propanediol over Pt/WO3/ZrO2catalysts in a fixed-bed reactor

Abstract

Deoxygenation of glycerol in aqueous medium catalyzed by Pt/WO₃/ZrO₂ at relatively low temperatures (110–140 °C) under hydrogen pressure range from 2 to 5 MPa in a fixed-bed continuous-flow reactor gives 1,3-propanediol (1,3-PDO) and n-propanol (n-PrOH) as the predominant products, indicating high selectivity for deoxygenation of the secondary hydroxyl group over the primary hydroxyl groups of the glycerol. The optimum catalyst was prepared by calcination of WO₃/ZrO₂ at 700 °C and loading of 3.0 wt% Pt with W content of 10 wt%. The effect of reaction temperature, hydrogen pressure and initial water content were evaluated to find the optimum reaction conditions. The glycerol conversion and the yield of 1,3-PDO greatly depended on these factors. At 130 °C, 4 MPa and 70.2% conversion, the yield of 1,3-PDO was up to 32.0% (1,3-PDO/1,2-PDO = 17.7). The proposed mechanism for glycerol deoxygenation in aqueous medium over Pt/WO₃/ZrO₂ is an ionic pathway involving proton and hydride ion transfer steps.