Synergistic effects of bimetals and hierarchical structures in Mg-Sn-Beta-H zeolites for lactic acid synthesis from biomass-derived carbohydrates

During the catalytic transformation of biomass into valuable chemicals, enhancing the yield of target products and inhibiting undesirable reactions are vital but challenging. In this study, a facile and efficient method for synthesizing a hierarchical bimetallic Mg-Sn-Beta-H zeolite was developed. Using this method, the simultaneous fabrication of catalytically active sites and hierarchical structures was achieved. Selective experiments and kinetic analysis confirmed that the catalytically active sites and hierarchical structures in the catalyst exhibited a clear synergistic effect on the transformation of glucose into lactic acid with a high yield of 62.7%, and the lactic acid yield remained above 58% after reusing the catalyst four times. An in-depth analysis of the synergistic catalysis mechanism demonstrated that strong and weak Lewis acidity in the catalytically active sites promoted the main reaction steps, including isomerisation and retro-aldol condensation, whereas the hierarchical structure induced by the introduction of magnesium into the parent Sn-Beta zeolite regulated the main reaction steps and suppressed the side reactions. The coupling of multifunctional active sites and hierarchical structures provides a new strategy for addressing the challenges of commercial lactic acid production.