Catalytic conversion of dimethyl ether into propylene over MCM-68 zeolite

•MCM-68 (MSE-type) catalysts with different Si/Al ratios were prepared.•The MCM-68 catalysts were applied to the DTO reaction.•Catalytic performance was highly dependent on aluminum content of the catalyst.•The DTO reaction over MSE-type zeolite gives propylene and butylenes in high yields.

Control of the acid site distribution on MCM-68 zeolite catalysts can be achieved by the acid treatment with nitric acid. Less coke is deposited during DTO reactions over dealuminated MCM-68 compared to the parent MCM-68 probably due to the selective removal of acid sites on the external surface of the parent MCM-68. The higher yields of propylene and butylenes are obtained with lower selectivity for ethylene and lower paraffins over dealuminated MCM-68, whereas ethylene and lower paraffins are predominant over parent MCM-68. The acid treatment may preferentially remove the strong acid sites, and thus the retained acid sites with moderate strength mainly convert dimethyl ether into propylene and butylenes with high propylene/ethylene (P/E) molar ratio. Besides the issue of high P/E ratio, the ratio is also widely controllable by changing the reaction temperature.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (253 K)Download as PowerPoint slide