An efficient sulfolane-modified resin catalyst for dimethoxymethane carbonylation

An easily-operated method was first developed to pretreat the sulfonic acid resin-based catalysts by using different solvents (such as n-hexane, toluene, acetone, methanol, dimethyl sulfoxide, and sulfolane), and the as-treated resins were applied in DMM carbonylation. Except for sulfolane, the higher dipole moment value of treatment-solvents resulted in higher turnover number (TON) but lower DMM conversion and MMAc selectivity. Arrhenius plot of SAresin-sulfolane-393K was generated from reaction rate data at various temperatures, and the apparent activation energy calculated was 18.39 kJ/mol. SAresin-sulfolane-393K exhibited an excellent activity and stability for 50 h with a STY of 3.15 mmolMMAc·(gcat·h)-1 and nearly 100% MMAc selectivity. Karl Fischer analysis, in situ FT-IR analysis of CO adsorption, and a static CO adsorption method indicated that the residual H2O of SAresin was significantly reduced, and CO adsorption capacity was obviously enhanced. Nitrogen adsorption-desorption, FT-IR spectrum, SEM and EDX-mapping images of SAresin-sulfolane-393K proved that larger average pore diameter and pore volume were generated, and sulfolane indeed entered the resin and changed the chemical composition of SAresin. FT-IR spectra of pyridine pre-adsorbed samples confirmed that the stronger acid strength for SAresin-sulfolane-393K was obtained. The unusual activity and stability of SAresin-sulfolane-393K were attributed to its stronger acid strength, low H2O content and excellent CO adsorption capability.