Single-Atom Zn Catalyst with ZnNx Active Sites Efficiently Promoted Meerwein–Ponndorf–Verley Reduction of Biomass-Derived Carbonyl Compounds

Meerwein–Ponndorf–Verley (MPV) reduction is a highly promising strategy to selectively convert biomass-derived carbonyl compounds. Cost-effective and efficient heterogeneous catalysts for MPV reduction are still highly desired. In this study, N-doped carbon-supported Zn-based catalytic materials (denoted as Zn@C-T, in which T was the pyrolysis temperature) was fabricated by the pyrolysis of Zn-based coordination polymer formed from ZnCl₂ and polyvinyl pyrrolidone. Very interestingly, the material prepared at 900 °C (Zn@C-900) showed excellent catalytic activity on MPV reduction of various biomass-derived carbonyl compounds to generate the corresponding alcohols, originating from the formed ZnN_x sites in Zn@C-900. Especially, the usage of Zn was only 0.6 mol%, which was much lower than the usage of Zr in the popular Zr-based catalysts, confirming the great potential of the Zn@C-900 in large-scale applications. Systematic investigations revealed that the excellent catalytic activity of Zn@C-900 was predominantly enabled by the synergistic effect of Zn (as Lewis acid sites) and N (as Lewis base sites) in the ZnN_x sites, which could simultaneously activate the carbonyl group in carbonyl compounds and the hydroxyl group in isopropanol, thereby significantly promoting the MPV reduction of carbonyl compounds. This work provided a cost-effective and efficient Zn-based catalyst for MPV reduction of biomass-derived carbonyl compounds.