An improved process is disclosed for the selective disproportionation of
toluene. The process preferably uses a disproportionation catalyst
comprising a pentasil type zeolite such as MFI that is bound with
aluminum-phosphate. Running the process at a toluene conversion greater
than about 30 wt-% and at a hydrogen-to-hydrocarbon ratio less than 3.0,
and especially a ratio of 0.1 to 1.0, improves the maximum yield of
para-xylene. Optional periodic rejuvenation by increasing the
hydrogen-to-hydrocarbon ratio removes some carbon deposits and restores
catalyst activity. An inert diluent gas assists in selective pre-coking
of the catalyst as well.