Efficient Catalyst Based on Pyridinium Modified MCM-41 for Carbon Dioxide Utilization

Pyridinium halide modified MCM-41 was used as a catalyst for the model reaction of styrene oxide with carbon dioxide. The modification was performed in two steps—first, the modification of MCM-41 by halogenopropyl triethoxy silane followed by the reaction with pyridine. The process was successful for the production of pyridinium bromide and iodide. The modification by chlorine was problematic. The prepared materials were characterized by available methods—XRF, XRD, EA, TPH, DVS, FTIR, UV/Vis, TGA, and nitrogen physisorption—confirming the successful formation of the desired material. For the catalysis, the strong interaction of pyridinium ion was necessary. The prepared materials containing bromine and iodine were used as efficient catalysts for the formation of styrene carbonate from styrene oxide. The achieved selectivity was up to 99% with TONs 5800 (calculated on the amount of loaded pyridine) under 1.2 MPa, 120 °C, without any solvent. Solvents negatively influenced the reaction rate. Dependently on halogen, the rate increased in the row Cl < Br < I modified MCM-41. The catalysts might be reused with only a slight loss of activity in the three following cycles. These materials represent simple, available, and promising catalysts for the reaction of epoxides with carbon dioxide. Graphical Abstract