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.
Ruliang Liu,Jinzhu Chen,Xing Huang,Limin Chen,Longlong Ma,Xinjun Li
A series of sulfonic acid-functionalized carbon materials (C–SO3H), including poly(p-styrenesulfonic acid)-grafted carbon nanotubes (CNT-PSSA), poly(p-styrenesulfonic acid)-grafted carbon nanofibers (CNF-PSSA), benzenesulfonic acid-grafted CMK-5 (CMK-5-BSA), and benzenesulfonic acid-grafted carbon nanotubes (CNT-BSA), have been studied for fructose dehydration to 5-hydroxymethylfurfural (HMF) and fructose alcoholysis to alkyl levulinate. A study for optimizing the reaction conditions such as the catalyst loading, the reaction time, and the temperature has been performed. Under the optimal conditions, high HMF and ethyl levulinate yields of up to 89% and 86%, respectively, are obtained. The catalytic activities of C–SO3H for the conversions of fructose into both HMF and ethyl levulinate follow the order of their acid strength. The relationship between the catalytic activity and acid density of C–SO3H shows a linear correspondence in the fructose dehydration to HMF. The facile separation, ease of recovery, and high thermal stability make the developed C–SO3H efficient and environment-friendly catalytic materials for transforming biomass carbohydrate into fine chemicals.