A Ag–ZrO2–graphene oxide nanocomposite as a metal-leaching-resistant catalyst for the aqueous-phase hydrogenation of levulinic acid into gamma-valerolactone

Cellulose-derived levulinic acid (LA) can be converted into gamma-valerolactone (GVL), a sustainable platform chemical for the production of bio-based chemicals. However, LA as an organic acid causes severe metal leaching during the heterogeneous hydrogenation of LA to GVL, especially in the presence of water. Various endeavors for preventing metal leaching have focused more on the process and less on the intrinsic nature of catalysts. The aim of this work is to derive a novel metal-leaching-resistant catalyst for the aqueous-phase hydrogenation of LA into GVL by using a nanocomposite containing three components, Ag, ZrO2, and graphene oxide (GO). The AgZrO2GO catalyst without pre-reduction treatment resulted in complete conversion of LA and approximately 100 mol% selectivity to GVL in the aqueous reaction, and metal leaching from the catalyst was completely eliminated. The relationship between the catalytic performance and the distinct physicochemical properties of the catalyst was extensively discussed.