Strong Oxophilicity of Zr Species in Zr4+-Exchanged Montmorillonite Boosted Meerwein–Ponndorf–Verley Reduction of Renewable Carbonyl Compounds

Abstract

Meerwein–Ponndorf–Verley (MPV) reduction of biomass-derived carbonyl compounds is a greatly promising route for biomass valorization. Robust, facile-prepared, and cost-effective inorganic Zr-based catalysts for this transformation remain highly desirable. Herein, Zr-containing montmorillonite (denoted as Zr-MMT) was constructed by the ion exchange of Zr4+ with the interlayer cations of montmorillonite (MMT). Very interestingly, as an inorganic catalyst, the prepared Zr-MMT showed high catalytic activity for MPV reduction of various biomass-derived carbonyl compounds. Systematic investigations revealed that the excellent performance of Zr-MMT predominantly originated from more positively charged Zr species ([Zrx(OH)y(H2O)n](4x−y)+), which could boost the activation of the carbonyl group and simultaneously promote the hydrogen transfer process assisted by suitable basic sites on MMT. Notably, the preparation of Zr-MMT avoided the utilization of surfactants or expensive organic ligands, and the prepared Zr-MMT showed better or comparable catalytic performance than most reported Zr-containing catalysts, significantly enabling it to be more practical.