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

Abstract

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 Al sites (EFAl) possessed proper number of Brønsted 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 Brønsted acidic sites. The most active tetrahedral T2 sites with two adjacent Al 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 Al 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.

Molecular Understanding of the Catalytic Consequence of Ketene Intermediates under Confinement

“…They concluded that the surface acetyl serves as the primary methylating agent toward hydrocarbon pool in zeotypes. Indeed, the relatively stable surface acetyl species are readily detected by solid-state 13 C NMR and FT-IR spectroscopy as the intermediate during the MTO , and DME/methanol carbonylation. , Acylium ion (CH 3 CO + ) may be formed during the acid-catalyzed reaction through interactions between the acylating agent (CH 3 COCl) and the Brønsted acid sites or via adsorption of CH 3 COCl in Lewis acidic AlCl 3 catalyst . The surface acetyl, rather than acylium ion, have been reported as the reactive intermediate species in both Friedel–Crafts acylation over H-Beta and Koch-type carbonylation over H-MOR zeolites up to date .…”

Morphology Effects of Ferrierite on Bifunctional Cu–ZnO–Al2O3/Ferrierite for Direct Syngas Conversion to Dimethyl Ether

“…previously calcined at 550 °C for 6 h was applied as a starting material (denoted as CFER). According to the previous reports, ,, the commercial FER seed was mixed with the solution composed of SiO 2 /NaAlO 2 /NaOH/water = 1.0:0.096:0.15:36 (molar ratio) with 24 wt % of the commercial FER seed based on a total weight of FER. After a vigorous mixing of the above solution, a hydrothermal synthesis was carried out at 160 °C for 4 days, followed by filtering, washing, and drying in an oven overnight.…”

A Carbonylation Zeolite with Specific Nanosheet Structure for Efficient Catalysis

“…However, precisely because of the specific spatial conformation of reactant DME and product MA, there is a serious limitation in exploiting/designing zeolite catalysts for such carbonylation reaction. At present, the generally accepted high-performance zeolite catalysts in carbonylation of DME to MA are H-MOR and H-ZSM-35. − Nevertheless, the occurrence of the MTO side reaction in 12-MR of H-MOR causes a rapid carbon deposition, which leads to a serious deactivation of this catalyst. , By contrast, H-ZSM-35, which has the 10-MR and 8-MR as the mass-transfer channel and reaction location, respectively, performs better reaction stability due to the lighter carbon deposit in smaller 10-MR . Recently, a EU-12 zeolite demonstrated the ability to achieve carbonylation of DME with a better stability .…”