Carbon-supported ruthenium catalysts containing different amounts of tin were studied for the hydrogenation of levulinic acid (LA) to gamma-valerolactone (GVL) in a 2-sec-butyl-phenol (SBP) solvent. Results from reaction kinetics measurements (453K and 35bar H 2) showed that the Ru/C catalyst was initially more active for hydrogenation of both LA and SBP (i.e., 0.051s -1 for conversion of LA to GVL), followed by continuous deactivation versus time on stream. In contrast, the catalyst containing equal amounts of Ru and Sn had a lower activity for LA to GVL conversion (0.005s -1), but displayed stable activity versus time on stream and showed 100% selectivity for hydrogenation of LA versus the SBP solvent. Increasing the amount of Sn to a 1 to 4 Ru:Sn atomic ratio creates an additional phase, β-Sn, that is not active for hydrogenation, leaches into the SBP solvent, and sinters under reaction conditions. Results from CO and O 2 chemisorption and electron microscopy measurements indicated that the Ru-based metal particles did not leach or sinter at reaction conditions, and that the surfaces of these particles became progressively enriched with Sn as the Sn-loading increases. In addition, Sn did not significantly leach from the catalysts when present as an intermetallic alloy with Ru, such as Ru 2Sn 3 and Ru 3Sn 7. Using LA produced from corn stover, the RuSn 4/C catalyst was stable and demonstrated that it is a promising catalyst to produce valuable chemicals and fuels from real biomass.
- Heterogeneous catalysis
- Renewable resources
ASJC Scopus subject areas
- Environmental Science(all)
- Process Chemistry and Technology