Shape selectivity of MWW-type aluminosilicate zeolites in the alkylation of toluene with methanol

We investigated the alkylation of toluene with methanol at 250 °C over MCM-22 and ITQ-2 zeolites possessing an MWW structure. Whereas ITQ-2, produced by the delamination of MCM-22 precursor, showed a poor p-xylene selectivity of 23% at 1.7% of the level of toluene conversion, a high p-xylene selectivity of 80% at 0.6% of the level of toluene conversion was obtained by poisoning the external surface of ITQ-2 with collidine. Similarly, MCM-22 treated with collidine showed a high p-xylene selectivity of 74% at 3.8% of the level of toluene conversion. We concluded that both interlayer and intralayer 10-membered ring (10MR) micropores in the MWW structure caused the shape-selective formation of p-xylene in the alkylation of toluene with methanol.

We investigated the alkylation of toluene with methanol over MCM-22 and ITQ-2 zeolites possessing an MWW structure. A high p-xylene selectivity was obtained by poisoning the external surface of ITQ-2 or MCM-22 with collidine. We concluded that both interlayer and intralayer 10MR micropores in the MWW structure caused the shape-selective formation of p-xylene in the alkylation of toluene with methanol.Figure optionsDownload as PowerPoint slide