γ-valerolactone from levulinic acid and its esters: Substrate and reaction media determine the optimal catalyst

Ni-based catalysts supported on sepiolite were synthesized by different preparation procedures for the production of gamma-valerolactone from levulinic acid and its esters (methyl levulinate and ethyl levulinate). The optimal performance was related to the formation of tiny nickel particles. Interestingly, the reaction conditions significantly influence the reactivity of the substrates. The catalytic performance of the optimal Ni/sepiolite catalyst was compared with two catalysts of ruthenium (supported on gamma-alumina or sepiolite). In all cases, the production of gamma-valerolactone depends on both the substrate employed and the reaction media. Overall, the preferred reaction media using the Ni-catalyst is 2-propanol whereas pressurized hydrogen in water is the best alternative for Ru-catalysts. In both cases, a reasonable stability has been observed after 3 cycles. Finally, the use of metallic Zn in an aqueous medium to provide hydrogen could not be considered as an appropriate option due to the lack of a stable behaviour.

Automated summary

Ni-based and Ru-based catalysts were compared for the production of gamma-valerolactone from levulinic acid and esters, with optimal performance of tiny nickel particles. Reaction conditions and media significantly influenced substrate reactivity, with Ni catalyst showing best results in 2-propanol. Stability was observed after 3 cycles for both Ni and Ru catalysts, while the use of metallic Zn for hydrogen supply in aqueous medium was deemed unsuitable due to lack of stability.