Tandem Lewis acid catalysis for the conversion of alkenes to 1,2-diols in the confined space of bifunctional TiSn-Beta zeolite

The generation of multifunctional isolated active sites in zeolite supports is an attractive method for integrating multistep sequential reactions into a single-pass tandem catalytic reaction. In this study, bifunctional TiSn-Beta zeolite was prepared by a simple and scalable post-synthesis approach, and it was utilized as an efficient heterogeneous catalyst for the tandem conversion of alkenes to 1,2-diols. The isolated Ti and Sn Lewis acid sites within the TiSn-Beta zeolite can efficiently integrate alkene epoxidation and epoxide hydration in tandem in a zeolite microreactor to achieve one-step conversion of alkenes to 1,2-diols with a high selectivity of >90%. Zeolite confinement effects result in high tandem rates of alkene epoxidation and epoxide hydration as well as high selectivity toward the desired product. Further, the novel method demonstrated herein can be employed to other tandem catalytic reactions for sustainable chemical production. Bifunctional TiSn-Beta zeolite was fabricated using a simple and scalable post-synthesis approach, and it was employed as an efficient catalyst for the tandem conversion of alkenes to 1,2-diols. The isolated Lewis acid Ti and Sn sites within the TiSn-Beta zeolite could efficiently integrate alkene epoxidation and epoxide hydration in tandem to achieve the selective conversion of alkenes into 1,2-diols with a high selectivity of >90%.