Modified H-mordenites were prepared and subjected to Xylene isomerization reaction to gain insight into surface chemistry of zeolite catalysis. Modification steps include ion-exchange with transition metal, steam treatment at 500 ℃ and dealumination with boiling hydrochloric acid.
The activity and shape selectivity of those variously treated mordenites on the liquid phase isomerization of xylene were compared with those of the untreated mordenites. The experiments were carried out under the condition of 5.8 g-xylene/（hr）(g-cat) at 260 ℃ and 30 atm.
Mordenites ion-exchanged with Co, Ni, and Fe salts as well as treated with steam at high temperature showed considerable reduction of deactivation. On the contrary the dealuminated mordenites are not effective for the selective isomerization of xylene and rather increase the disproportionation of xylene.