Comparison of Dimethyl Ether Carbonylation Performance over Some Zeolites Containing 8-Member Ring Pores

Dimethyl ether (DME) carbonylation to methyl acetate (MA) together with the subsequent hydrogenation of MA to ethanol fuel opens a new ethanol production route from coal and natural gas. The zeolite-catalyzed carbonylation reaction represents a new and promising route. However, only a few zeolites have been reported with DME carbonylation capacity, and the known zeolites usually suffer from rapid deactivation. Here, a highly attractive dimethyl ether (DME) carbonylation performance is realized over T zeolite. Interestingly, by selectively shielding the acid sites located in the 12-member ring (12-MR) channel of T zeolite, the catalytic stability can be largely improved. Compared with the accepted carbonylation zeolite catalyst, T zeolite exhibits a better catalytic stability than commercial H-MOR zeolite. In addition, we found that the formation of coke and MA is catalyzed by the acid sites located in the 12-MR and 8-MR channels, respectively. After further investigating the DME carbonylation performance over a couple of 8-MR-containing zeolites, we proposed that the carbonylation activity is mainly determined by both the number of strong acid sites in the 8-MR channel and the size of the 8-MR channel. In addition, the transition-state shape selectivity for MA formation is also governed by the 8-MR pore configuration.

Automated summary

This study investigates the performance of T zeolite in the dimethyl ether (DME) carbonylation reaction and proposes a method to improve catalytic stability. The results show that the catalytic stability can be largely improved by selectively shielding specific acid sites. In addition, it is found that coke and methyl acetate formation are catalyzed by different acid sites. The transition-state shape selectivity for methyl acetate formation is also influenced by the pore structure.