Abstract: A dual function composite catalyst for isomerizing an isomerization feed containing an aromatic C.sub.8 mixture of ethyl benzene and xylene, comprises (a) a crystalline aluminosilicate zeolite having a low acid activity as measured by an alpha value of from 0.02 to 11, an average crystal size of not more than 0.4 microns for at least 50% by weight of the crystals, a silica to alumina ratio of at least about 12, a constraint index of about 1 to 12, a xylene sorption capacity greater than 1 gram per 100 grams of zeolite, and an ortho-xylene sorption time for 30 percent of said capacity less than 10 minutes, said sorption capacity and sorption time being measured at 120.degree. C. and a xylene pressure of 4.5.+-.0.8 mm of mercury, and (b) a supported metal of Group VIII of the Periodic Table having a high hydrogenation/dehydrogenation activity to provide the catalyst with a dehydrogenation activity of at least 10. The catalyst has an alpha value of 0.005 to 3.

Abstract: A dual function composite catalyst for isomerizing an isomerization feed containing an aromatic C.sub.8 mixture of ethyl benzene and xylene, comprises (a) a crystalline aluminosilicate zeolite having a low acid activity as measured by an alpha value of from 0.02 to 11, an average crystal size of not more than 0.4 microns for at least 50% by weight of the crystals, a silica to alumina ratio of at least about 12, a constraint index of about 1 to 12, a xylene sorption capacity greater than 1 gram per 100 grams of zeolite, and an ortho-xylene sorption time for 30 percent of said capacity less than 10 minutes, said sorption capacity and sorption time being measured at 120.degree. C. and a xylene pressure of 4.5.+-.0.8 mm of mercury, and (b) a supported metal of Group VIII of the Periodic Table having a high hydrogenation/dehydrogenation activity to provide the catalyst with a dehydrogenation activity of at least 10. The catalyst has an alpha value of 0.005 to 3.