Transfer hydrogenation of levulinic acid to γ-valerolactone over acid site-modified CuNi alloy

In the process of converting biomass into high value-added chemicals, transfer hydrogenation as a mild hydrogenation method has attracted more and more attention. The catalysts with hydrogenation sites (nano CuNi alloy) and acid sites (Al oxide) highly dispersed on the surface of a stable support (active carbon) were prepared and the importance of acid sites for the activity of CuNi catalysts in transfer hydrogenation was demonstrated. The catalysts showed promising catalytic activity on the transfer hydrogenation of levulinic acid (LA) to γ-valerolactone (GVL). The CuNi-1Al/AC with 5 wt.% CuNi alloy and 5 wt.% Al got 97.2% GVL yield and 100% LA conversion at 220 ℃ in isopropanol for 2 h. The high activity of the catalyst is attributed to the promoted esterification by the supported acid sites. The Al-modified catalyst also showed activity for esterification reaction in different alcohol hydrogen donors. The catalyst occurs inactive during the cycle due to the shedding of the active components, and the stability of catalyst is effectively improved by a stepwise impregnation. Graphical abstract