Acid-modified mordenite for enhancing methyl acetate production from dimethyl ether carbonylation

A series of mordenite zeolites were prepared by a simple acid treatment in the presence and absence of templates for dimethyl ether carbonylation to methyl acetate. The structure and acidity of the prepared catalysts were characterized by XRD, BET, SEM, NH3-TPD, FTIR and TG. The nitric acid treatment mainly removed nonframework Al atoms in zeolites, thereby improving the crystallinity of samples, which was also protected by the template. Also, the specific surface area and mass transfer were improved due to the increase in porous structure and surface roughness. Furthermore, compared to 8-MR, the Br & Oslash;nsted acid sites in 12-MR can be reduced to a greater extent. And the protective effect of template molecules on the Al atom can maintain a relatively high level of Br & Oslash;nsted acid sites in mordenite. The relatively high Br & Oslash;nsted acid sites in 8-MR served as active sites. Meanwhile, the significant reduction of Br & Oslash;nsted acid content within 12-MR effectively inhibited carbon accumulation and improved the stability of the carbonylation reaction. M-0.1 exhibited the best catalytic performance, with DME conversion rate and MA selectivity of 72.75% and 96.14%, respectively. Therefore, retention of the organic template during acid treatment is an effective approach to improve the carbonylation activity.