(120d) Enhancing Catalytic Efficiency and Stability in Oxidative Carbonylation Via Pervaporation-Assisted Membrane Reactors

Membrane reactor (MR) systems effectively enhance reaction performance by equilibrium shift through in situ removal of by-products during the reaction. Oxidative carbonylation of alcohols, a representative C1 chemical transformation that has been extensively studied for the synthesis of dialkyl carbonates (DACs). In our previous study, the Se/DMAP catalytic system of MEG afforded bis(2-methoxyethyl) carbonate (BMEC) with 60% yield at 50 ^oC[1]. However, the formation of water as a by-product in this reaction perturbs the reaction equilibrium, thereby further hampering the overall efficiency and deactivating the catalyst. Furthermore, under continuous flow conditions, selenium was prone to leaching, and the leached species are subsequently carried out with the product stream, presenting a significant challenge for scale-up.

In this study, a pervaporation-assisted circulating membrane reactor (PV-MR) system was developed to overcome these limitations. A hydrophilic zeolite membrane enabled continuous removal of water during the reaction, thereby shifting the reaction equilibrium and enhancing overall efficiency. Simultaneously, continuous circulation of the reaction solution facilitated the retention of leached selenium species, minimizing catalyst loss and enhancing long-term stability. In particular, Se-catalyzed packed-bed membrane reactor (PBMR) and Se@LTA catalytic membrane reactor (CMR) were also developed, achieving optimized conditions and significantly higher yields than conventional process. These findings are expected to contribute to the development of process for the oxidative carbonylation, CO₂ carboxylation, and related water generating transformations.

Ref. [1] H. Lee, T. Nguyen, A. Tran, H. Kim, Y. Suh, J. Baek and Y. Kim., Engineering pKa Value of Tertiary Amine for Enhanced Production of Dialkyl Carbonate via Se-Catalyzed Oxidative Carbonylation. Ind. Eng. Chem. Res. 2023, 62