Highly selective and multifunctional chitosan/ionic liquids catalyst for conversion of CO2 and methanol to dimethyl carbonates at mild reaction conditions

The direct reaction of CO2 and methanol is the most attractive route for dimethyl carbonates (DMC) synthesis from the point of green chemistry and sustainable development. In this work, a 10 wt% chitosan/ionic liquid (IL)-catalyst system having hydroxyl and amine groups as nucleophilic and carbon dioxide absorption sites was synthesized for DMC synthesis. This method provides an example of how an abundant biopolymer can be dissolved in IL for direct use as an electron-rich amino or hydroxyl group source for CO2 capture, which extends the scope of efficient DMC synthesis. The catalyst was characterized by Wide Angle X-ray diffraction (WAXRD) to confirm the structural distortion of crystalline chitosan where resultant active groups will be available for CO2 absorption. The catalyst showed excellent catalytic activity, selectivity and stability under mild conditions: 16.90% methanol conversion and ∼98.72% DMC selectivity. The catalytic performance revealed that the as-prepared “green” catalyst is very active and reusable for the DMC synthesis.