MoO2(acac)2-encapsulated in TS-1 zeolite catalyst for CO2 coupling with olefins to cyclic carbonates
The coupling of CO2 with olefins to produce cyclic carbonates has emerged as an important research topic in sustainable chemistry, owing to its high atom economy and the wide applicability of the resulting products. However, this reaction faces a significant challenge due to the mismatch between the rates of the epoxidation and cycloaddition steps. In this work, a series of TS-1 zeolite catalysts encapsulating different amounts of molybdenum acetylacetonate were prepared through hydrothermal synthesis followed by post-treatment, with the aim of elucidating the rate balance between the epoxidation and cycloaddition steps and the underlying regulation mechanism. Characterization results show that the Mo species were present as highly dispersed molybdenum acetylacetonate complexes that were stably confined within the TS-1 framework. These complexes interact electronically with the tetra-coordinated Ti sites to form synergistic active centers, while imposing negligible effects on the zeolite structure and porosity. In the CO2-styrene coupling reaction, tuning the Mo loading enabled effective control over the epoxidation rate, thereby achieving an appropriate balance with the subsequent cycloaddition step. The optimized catalyst delivered excellent performance under mild conditions, with a styrene conversion of 83.4% and a selectivity of 75.3%, and also exhibited outstanding recyclability. Overall, this encapsulated catalyst successfully addresses the dual challenges of rate matching and active-site stability in CO2–olefin coupling, providing valuable insights for the rational design of efficient, durable bifunctional catalysts.