Production of paraxylene

A process for preparing paraxylene comprising:

• (a) contacting a C8 aromatic hydrocarbon mixture including ethylbenzene and at least one xylene isomer other than paraxylene, in the presence of hydrogen and under suitable ethylbenzene de-alkylating conditions, with at least a first catalyst having an average crystal size of greater than 1 micron and comprising at least a first hydrogenation component, said component supported on a molecular sieve, wherein said catalyst is suitable for de-alkylation of ethylbenzene and further characterized as having been subjected to a sulfiding treatment prior to said contacting, to produce a ethylbenzene-depleted aromatic hydrocarbon mixture;
• then
• (b) contacting said ethylbenzene-depleted C8 aromatic hydrocarbon mixture, in the presence of hydrogen and under suitable xylene isomerization conditions, with at least a second catalyst having an average crystal size of 0.02 to 0.05 microns and comprising at least a second hydrogenation component, said component supported on a molecular sieve, wherein said catalyst is suitable for xylene isomerization and further characterized as having been subjected to a sulfiding treatment prior to said contacting, to produce a paraxylene-enriched C8 aromatic hydrocarbon mixture, when compared with said C8 aromatic hydrocarbon mixture of step (a),
• wherein each of said molecular sieves of the first and second catalysts is independently selected from the group consisting of ZSM-5, ZSM-11, ZSM-12, ZSM-22, ZSM-23, ZSM-35, ZSM-38, ZSM-48, ZSM-57, ZSM-58, and mixtures thereof, wherein said first catalyst has a higher alpha value than said second catalyst, wherein at least one of the first and second catalysts is not silica selectivated and wherein said first and second hydrogenation components are each independently selected from Groups 6-11 and 14-15 of the Periodic Table.