PII.096 Aqueous phase hydrogenation of β-hydroxybutyric acid to 1,3-Butanediol over Ru catalysts: effect of temperature, support, and mechanistic investigation

Resumo

This contribution reports the aqueous-phase hydrogenation of the PHB monomer β-hydroxybutyric acid (HBA) to 1,3-Butanediol (1,3-BDO), a high value-added product, over Ru catalysts. The reaction was studied with a 5.0%Ru/C commercial and 0.3%Ru/TiO₂, 1.7%Ru/TiO₂ and 0.2%Ru/SiO₂ synthesized catalysts. X-Ray Diffraction analyses suggest larger Ru particles on SiO₂ than on TiO₂. Over Ru/C, HBA conversion and 1,3-BDO selectivity increased and decreased harshly, respectively, with temperature increase from 130 to 170 ºC. The synthesized catalysts presented improved selectivity in comparison to the commercial, reaching 73.8% over 1.7%Ru/TiO₂. Even though the 0.2Ru%/SiO₂ catalyst showed conversion turnover number about six times higher than the other samples, side reactions producing 2-Propanol and 2-Butanol in significant amounts, were more pronounced on the SiO₂ supported material, suggesting an effect of interaction metal-oxide. A mechanistic study was conducted by modifying reaction conditions. Results indicate that 1,3-BDO undergoes dehydration to 2-Butanol and dehydrogenation to 4-Hydroxy-2-Butanone, possibly an intermediate in the production of 2-Propanol by a C-C cleavage pathway.