High-Efficiency Catalytic Transfer Hydrogenation of Biomass-Based 5-Hydroxymethylfurfural to 2,5-Bis(hydroxymethyl)furan over a Zirconium-Carbon Coordination Catalyst

Constructing a cheap and high-performance catalyst is very important for the selective synthesis of biomass- based 2,5-bis-(hydroxymethyl)furan (BHMF) from 5-hydroxymethylfurfural via the strategy of catalytic transfer hydrogenation (CTH). Herein, we synthesized a neoteric zirconium-carbon coordination catalyst (Zr-HTC) via a simple self-assembly method, in which glucose-derived hydrothermal carbon (HTC) containing abundant carboxyl and phenolic hydroxyl groups was directly used as a low-cost organic ligand. Satisfyingly, Zr-HTC showed an outstanding catalytic activity for the selective synthesis of BHMF in isopropanol (iPrOH). After 4 h at a mild temperature of 120 degrees C, 99.2% BHMF yield with 5.61 h(-1) turnover frequency (TOF) could be obtained. Detailed experimental results demonstrated that this outstanding catalytic activity of Zr-HTC was mainly contributed by the synergetic effects of Lewis acid-base sites (Zr4+-O2-) with high contents, proper ratios, and strengths under the aid of good hydrophilicity. In addition, Zr-HTC displayed superior catalytic stability, and when it was repeatedly used for five reaction cycles, no noticeable decrease in BHMF yield was found. More significantly, Zr-HTC could also effectively convert a wide range of carbonyl compounds, such as 1-butanal, 1-hexanal, furfural, cyclohexanal, benzaldehyde, phenylacetaldehyde, cyclopentanone, cyclohexanone, levulinic acid, and ethyl levulinate, to the relevant products in iPrOH. Overall, this work offers a new viewpoint to develop more practical zirconiumcontaining coordination catalysts for the selective synthesis of valuable chemicals via CTH.