Carbonylation of dimethyl ether on ferrierite zeolite: Effects of crystallinity to coke distribution and deactivation

Different distributions and locations of coke precursors on the highly crystalline seed-derived ferrierite (FER) altered the catalytic stability during carbonylation of dimethyl ether (DME) in a gas-phase. The larger amounts of heavy cokes on external Brønsted acidic sites of the FER were responsible for a fast deactivation, and their distributions on the active internal Brønsted acid sites such as 8-membered ring (8-MR) channels were largely affected by their crystallinity. Although the surface cokes on the FERs were inevitably formed, the FER having an optimal Brønsted acid site concentration in its 8-MR channels which were formed by recrystallization of Lewis acidic extra-framework Al species during a seed-assisted OSDA-free synthesis step, revealed slower deactivation rate at the proper seed content in the range of 7–15 wt%. The slow deactivation phenomena on the seed-derived crystalline FERs, especially on the optimal FER(S15) and FER(S7) having the proper amount of crystallization sites were originated by minimizing the coke depositions on the external surfaces.