Product distribution in the conversion of methanol on partially ion-exchanged mordenites

Abstract

The conversion of methanol to hydrocarbons over ion-exchanged mordenites was investigated by a pulse reaction technique. The change in the activity and selectivity of mordenites as reaction conditions were varied was similar to that of ZSM-5 zeolite. Bro¨nsted acidity was measured from the intensity of the 1447 cm −1 IR band of adsorbed ammonia. Product distribution and Bro¨nsted acidity depended on the nature and extent of cation exchange. The decrease of Bro¨nsted acidity results in increase in olefin and aromatic yields and in decrease in coke deposit. The deposition of coke, moreover, depends on the strength of Bro¨nsted acid sites. In the reaction pathway, the important and reactive intermediates are the C 3 and C 4 species. A 7 and A 8 aromatics are alkylated to higher polyraethylbenzenes. The carbonaceous deposit is mainly formed from the polymethylbenzenes at strong and/or numerous Bro¨nsted acid sites.