Synthesis of dimethyl carbonate from CO 2 catalyzed by spherical polymeric ionic liquid catalyst

Dimethyl carbonate (DMC) is widely used and nontoxic and can replace more dangerous materials such as dimethyl sulfate or methyl chloride. Spherical particle catalysts (PILs-XSS) were synthesized by suspension polymerization, which was characterized by SEM–EDS, FT-IR, TG, and BET-BJH. The characterization results showed that PILs-XSS had a specific core structure, a certain pore size (14.3 nm), and surface area size (71.5m 2 /g) and remained stable at 293.4 °C. The catalyst performance was evaluated by a one-pot synthesis of dimethyl carbonate. The process conditions were optimized in detail. The optimal reaction conditions were as follows: the dosage of PILs-XSS was 2.5 wt %, the CO 2 pressure was 1.5 MPa, the reaction temperature was 100 °C, the reaction time was 4 h, the molar ratio of methanol to propylene oxide (PO) was 3: 1, and the dosage of cocatalyst Na 2 CO 3 was 3 wt %. Under the optimum conditions, the conversion of PO was up to 98.8% and the yield of DMC reached 53.7%. In addition, the combined catalyst PILs-Na 2 CO 3 was easily recovered by filtration in the reaction system. After five times of repeated use, the activity and the shape of the catalyst were almost unchanged, which meant that the catalyst had amazing mechanical strength. This study found that the transesterification catalyst Na 2 CO 3 not only had good transesterification efficiency but also promoted the reaction of CO 2 . Graphical abstract