Development of the CON-type Aluminosilicate Zeolite and Its Catalytic Application for the MTO Reaction

The CON-type aluminosilicate zeolites, which consist of a three-dimensional pore system with 12-, 12-, and 10-membered ring pores have been prepared by postsynthesis and the newly developed direct-synthesis methods. We first found that the CON-type aluminosilicate zeolites exhibited a higher catalytic performance in the methanol to olefins (MTO) reaction in terms of duration and propene selectivity than the MFI and *BEA-type aluminosilicate zeolites. They exhibited high propene selectivity, low ethene selectivity, and a very long catalytic life compared to Beta and ZSM-5; the selectivity for C3-C4 olefins reached 80%. Interestingly, the CON-type aluminosilicate zeolite synthesized by the direct-synthesis method showed a much longer catalytic lifetime than the one obtained by the postsynthesis method. The Al-27 MAS and Al-27 MQMAS NMR spectra suggest that there is a significant difference in the state of tetrahedrally coordinated Al species between the directly and postsynthesized zeolites, leading to the marked difference in the catalytic performance.