Remarkable enhancement of catalytic activity and selectivity of MSE-type zeolite by post-synthetic modification

Besides conventional MCM-68, Al-rich MSE-type zeolites with a 12-10-10-ring micropore system were successfully synthesized in a remarkably short crystallization period by some different synthetic methods: (1) hydrothermal conversion of an FAU-type zeolite with the aid of the dipyrrolidinium-type organic structure-directing agent (OSDA) and (2) hydrothermal synthesis without using any OSDA with the aid of seed crystals. The dealumination behaviors during post-synthetic acid treatments as well as the properties of the products differed depending on the synthetic method. The dealuminated version of each Al-rich MSE-type zeolite showed a high level of coking resistance in addition to a significant yield of propylene in the hexane-cracking reaction, and the MSE synthesized under OSDA-free conditions showed the best catalytic performance among three different MSE-type zeolites after post-synthetic modification. The Al-rich MSE products obtained in this work are promising parent materials for industrial applications as highly selective and long-lived catalysts.