Carbonylation of Methanol on Metal–Acid Zeolites: Evidence for a Mechanism Involving a Multisite Active Center

Direct Synthesis of Ethanol from Dimethyl Ether and Syngas over Combined H‐Mordenite and Cu/ZnO Catalysts

“…In contrast, for the physically mixed catalysts, the low conversion of DME and high selectivity of methanol were observed. ester [8][9][10] or acetic acid, [11,12] respectively, has attracted much attention. Iglesia and co-workers reported that H-MOR was very active and selective for DME carbonylation to methyl acetate (MA) at the low temperature from 423 to 463 K, [8,9] and the active sites for carbonylation located in the 8-member-ring (8-MR) channel.…”

“…The carbonylation reaction would be seriously hindered because of the competitive adsorption between water and MeOH on the acidic sites of the zeolite catalyst. [11,14] Therefore, DME is the more suitable feedstock for the carbonylation reaction than MeOH over the H-MOR zeolite. Furthermore, DME carbonylation seems more favorable than MeOH from the economic viewpoint because it can directly be produced from syngas with enhanced efficiency.…”

“…Thereafter, the obtained acetyls reacted with another DME molecule to produce MA and to regenerate the surface methoxy. [11][12][13] If MeOH is substituted for DME here, a lot of water would be produced through MeOH dehydration. The carbonylation reaction would be seriously hindered because of the competitive adsorption between water and MeOH on the acidic sites of the zeolite catalyst.…”

“…[20] The competitive adsorption between DME and MeOH in the 8-MR channel on the H-MOR catalyst, which was regarded as the active centers for DME carbonylation, also hindered the proceeding of DME carbonylation. If the raw material DME was substituted by MeOH, the proton at the acidic sites would be regenerated as shown in Equation (11). Thereafter, a lot of water could be produced in Equation (6).…”

Coking on micrometer- and nanometer-sized mordenite during dimethyl ether carbonylation to methyl acetate

“…In this reaction, DME initially reacts with CO to form MA on a solid zeolite, which is followed by the hydrogenation of MA to ethanol over supported copper catalysts [1][2][3]. H-mordenite (HMOR) is the most active catalyst for DME carbonylation to MA [4][5][6][7][8][9][10][11][12][13][14], but the HMOR catalysts suffered severe deactivation due to the heavy deposition of carbonaceous species during reaction. Mordenite has a two dimensional framework structure consisting of straight 12-membered ring (12-MR) pores (0.67 nm × 0.70 nm) that are connected by twisted (0.28 nm × 0.57 nm, side pockets along (001) crystal facet) and crossed (0.34 nm × 0.48 nm, along (010) crystal facet) 8-membered ring (8-MR) pores [14,15].…”