Gas-Phase Carbonylation of Dimethyl Ether on the Stable Seed-Derived Ferrierite

The higher catalytic activity and stability for a gas-phase carbonylation of dimethyl ether (DME) to methyl acetate (MA) on the seed-derived ferrierite (FER) were attributed to its higher crystallinity with small amounts of defect sites by recrystallization methods without using any organic structure directing agent. The recrystallized FER (FER-S1) with its smaller amount of Lewis acidic extraframework AI sites (EFAI) possessed proper number of Bronsted acidic sites in the eight-membered-ring (8-MR) channels in comparison to the pristine FER, which was responsible for an enhanced CO insertion rate to methoxy intermediates formed by dissociated DME molecules by referentially forming acetyl intermediates or to the highly active Bronsted acidic sites. The most active tetrahedral T2 sites with two adjacent AI atoms in the 8-MR channels having next-nearest Al-O-Si-O-Al configurations on the FER-S1 revealed the stronger adsorption of the stably adsorbed DME molecules as confirmed by DFT calculations. FER-S1 containing the proper amounts of Al atoms in the 8-MR with appropriate locations with optimal acidic properties was responsible for its higher activity and stability for the gas-phase carbonylation of DME, where the AI distributions were confirmed by Rietveld refinement XRD analysis, FT-IR, and DFT calculations. In addition, the acidic sites on the outer surfaces and larger cavity including 10-MR channels were responsible for an accelerated formation of aromatic coke precursors.