An integrated distributor-type ceramic membrane reactor for continuous CO₂ cycloaddition to cyclic carbonate

The cycloaddition of epoxides with CO₂ to synthesize cyclic carbonates represents a critical pathway for CO₂ conversion and utilization, but it faces a key challenge in gas-liquid mass transfer limitations. In this study, an innovative bifunctional ceramic membrane reactor was developed that integrates gas distributor and catalytic reaction within a single unit, thereby overcoming the limitations of traditional premixed reactors where microbubble coalescence and breakup hinder the mass transfer efficiency. Using the model reaction of CO₂ cycloaddition with epichlorohydrin (ECH), we demonstrated that the membrane distributor system significantly enhanced the reaction process, achieving 1.74 times increase in the ECH conversion compared to direct gas feeding under identical conditions. The parameters of membrane pore size and gas-liquid ratio were investigated to explore optimal gas distribution conditions for the membrane reactor. Remarkably, with only 2 % DMF addition, the cyclic carbonate yield remained at above 88 %. Moreover, the membrane reactor maintained stable performance over 40 h with a productivity of 7.6 mol·L⁻¹·h⁻¹, surpassing the majority of reported fixed-bed reactor systems for CO₂ cycloaddition. This work provides a novel strategy for intensifying multiphase catalytic reactions in the integrated distributor-type membrane reactor.