Dimethyl Ether Carbonylation in the Presence of an H-MOR Zeolite Modified with Copper, Cobalt, and Magnesium

Abstract

The adsorption, temperature-programmed desorption, and carbonylation of dimethyl ether (DME) in the presence of mordenite and ferrierite (SiO₂/Al₂O₃ ≈ 20, Zeolyst International) is studied. The effect of introducing Cu, Co, and Mg cations by ion exchange is discussed. Dimethyl ether carbonylation is conducted at 200°С, a pressure of 3 MPa, and a space velocity of 8000 mL g^–1 h^–1 in the following mixture (vol %): DME, ⁓2.2; CO, 92.8–95.5; and the rest, N₂. After an induction period, the methyl acetate content in the presence of mordenite is about 4–5 times higher than that in the presence of ferrierite. Water, methanol, and hydrocarbons are formed in trace amounts. The introduction of Cu, Co, and Mg cations into mordenite by ion exchange (single ion-exchange run, cation/Al ratio of no more than 35%) leads to an increase not only in stability, but also in activity in the DME carbonylation reaction. It is found that an increase in the content of copper (from 1.19 to 2.23 wt %) and magnesium (from 0.62 to 1.8 wt %) has different effects on activity. It increases in the case of copper and decreases in the case of magnesium. The prereduction of a copper-exchanged mordenite leads to the appearance of metallic copper particles on the surface of the mordenite crystallites and a decrease in activity. According to in situ diffuse reflectance infrared spectroscopy, the introduction of magnesium cations by three ion-exchange runs leads to a significant decrease in the number of Brønsted acid sites (BASes) in both the 12-MR and 8-MR channels of the mordenite. The catalytic characteristics of ferrierite hardly change upon the introduction of copper and magnesium by ion exchange.