Biomass carbon quantum dot-Zr hybrids as excellent and recyclable catalysts for catalytic transfer hydrogenation of furfural to furfuryl alcohol in isopropanol

The low-polymerized Zr-O-Zr units in hydrous ZrO2(H) are very active for the catalytic transfer hydrogenation (CTH) of furfural to furfuryl alcohol, but during CTH process, they easily turn into high- polymerized states by dehydration among their Zr-OH groups, resulting in the deactivation of ZrO2(H). This work discloses that using bamboo powder-derived biomass carbon quantum dot (BCQD) and ZrCl4-derived ZrO2 sol nanoparticles (2-5 nm NPs) as the basic framework units, a network structure hybrid BCQD-Zr with is conveniently fabricated in lost cost under mild dehydration conditions. Due to the enhanced Lewis acidity and stability of Zr-O-Zr and Zr-O-C species, the suggested BCQD-Zr is very efficient and stable to the above CTH reaction in isopropanol medium and the best one can achieve up to 99.9% furfural conversion with 98.4% furfuryl alcohol yield under the optimized reaction conditions and still keep an excellent CTH activity and selectivity after the fifth cycle run, which is superior to most of the analogous catalysts reported at present in terms of catalyst availability, catalysis efficiency or recyclability. This work provides a potential way to fully use discarded biomass but also low-cost and high-performance of Zr-based catalyst for the CTH conversion of furfural to furfuryl alcohol.