Pt/Al2O3 Catalyzed 1,3-Propanediol Formation from Glycerol using Tungsten Additives

Screening of four commercial catalysts (Pt/Al2O3, Pt/SiO2, Pd/Al2O3, and Pd/SiO2) and four acidic additives (hydrochloric, tungstic, phosphotungstic, and silicotungstic acids) shows that the combination of a platinum hydrogenation catalyst with tungsten containing acidic additives yields 1,3-propanediol from aqueous glycerol. The performance of the best catalytic system Pt/Al2O3 with silicotungstic acid as an additive was optimized by experimental design, capturing the influence of reaction time, glycerol concentration, acid concentration, pressure, and temperature on the formation of 1,3-propanediol from glycerol. High 1,3-propanediol yield in an aqueous batch system can be achieved (49% conversion, 28% selectivity) with excellent 1,3-propanediol to 1,2-propanediol ratios. A mechanistic interpretation is given for this bifunctional system, supported by the relative stability of 1,3-propanediol in comparison with 1,2-propanediol under the chosen reaction conditions.