One-pot cascade conversion of furfural to isopropyl levulinate catalyzed by sulfonic acid-functionalized UiO-66

A porous sulfonic acid-functionalized zirconium-based metal–organic framework possessing both Lewis acid and Brønsted acid sites (UiO-66-SO 3 H) was synthesized and tested for the selective conversion of furfural (FUR) to isopropyl levulinate (IPL) through one-pot cascade reaction. UiO-66-SO 3 H exhibited excellent catalytic performance, and the conversion of FUR as well as the yield and selectivity of IPL reached 96.4 %, 86.0 %, and 89.2 %, respectively. UiO-66-SO 3 H could be simply recovered and reused, but the catalytic performance was significantly decreased. The FUR conversion and IPL yield dropped to 73.8 % and 65.1 %, respectively, after 1 cycle, and the reason for the decrease in the catalyst activity were also investigated. It was found that the decrease was mainly caused by the loss of some −SO 3 H groups, and the cyclic performance of UiO-66-SO 3 H could be restored by supplementing a small amount of BDC-SO 3 Na. A plausible mechanism for the selective synthesis of IPL from FUR was proposed, wherein both Lewis acid and Brønsted acid sites played important roles. This work provides guidance for the selective conversion of FUR into IPL, and the high-valued utilization of biomass and its derivatives.