Synthesis of propylene glycol methyl ether catalyzed by imidazole polymer catalyst:Performance evaluation, kinetics study, and process simulation

Abstract An imidazole polymer (divinylbenzene-vinylimidazole) catalyst (P-DVB-VIM) was developed for production of the eco-friendly solvent propylene glycol methyl ether (PGME) by the propoxylation reaction of propylene oxide (PO) with methanol (ME). The catalyst was characterized in detail by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and Brunauer-Emmett-Teller (BET) analysis. 1H-NMR was used to characterize the structural features of the catalyst precursor, i.e., the linear polymer of vinylimidazole (PVIM). An “electrophile nucleophile dual activation” ring-opening mechanism was proposed based on the “cooperative effect” of the reactant and PVIM. The catalytic performance was investigated and optimized at 100–130 ℃ using an autoclave batch reactor. The results reveal that the P-DVB-VIM shows excellent catalytic performance, exhibiting the highest turnover frequency (TOF) number at 120 °C within 45 min. The reaction kinetics was systematically studied using the pseudohomogeneous (PH) kinetic model. The kinetic parameters were determined by non-linear regression analysis of the experimental data. Validation of the model showed that the experimental data were in good agreement with the predicted outcomes. Moreover, based on the proposed kinetic model, steady-state simulations of the production of PGME in a fixed-bed reactor were carried out to determine the optimal design parameters, thus providing a useful guide for the design and production of PGME on the industrial scale.