Lewis Acidic Zeolite-Encapsulated Bimetallic Au–Pt Nanoparticles as Robust Catalysts for the Conversion of Glycerol to Methyl Lactate

Abstract

Alkyl lactates can be produced via a glycerol oxidation-rearrangement route, which is a promising alternative to the microbial fermentation-based technology but is still hindered by the lack of an efficient catalyst. Herein, we reported the successful fabrication of well-defined bimetallic Au–Pt nanoparticles confined inside the Snβ zeolite, i.e., Au_xPt_y@Snβ, using a mercaptosilane-assisted structure reconstruction strategy. Owing to the synergistic effect of bimetallic Au–Pt species and the unique Lewis acidic framework Sn, the optimized Au₁Pt₃@Snβ demonstrated superior catalytic performance in the conversion of glycerol to methyl lactate, achieving a 78.8% methyl lactate yield and a TOF of 335 h^–1 at 413 K and 0.5 MPa air, which surpasses most previously reported heterogeneous catalysts under similar reaction conditions. The confinement environment of zeolite can not only provide spatial restriction but also induce a strong interaction between encapsulated Au–Pt nanoparticles and framework Sn, thus inhibiting metal sintering and leaching during catalysis. Experimental and theoretical calculations (DFT) results explicated the critical role of bimetallic Au–Pt synergy in activating O₂ and facilitating a lower energy barrier for glycerol dehydrogenation, thereby promoting the catalytic performance.