Heavy Aromatics Conversion Processes and Catalyst Compositions Used Therein

A process for conversion of a feedstock comprising C8+ aromatic hydrocarbons to lighter aromatic products, the process comprising the steps of:

• a) contacting said feedstock and optionally hydrogen in the presence of a first catalyst composition under conversion conditions effective to dealkylate said C8+ aromatic hydrocarbons and to saturate C2+ olefins formed so as to produce a first effluent comprising at least one C6-C7 aromatic hydrocarbon and remaining C8+ aromatic hydrocarbons,
• wherein said first catalyst composition comprises:
• (i) a first zeolite which has a constraint index from greater than 3 up to 12, said first zeolite being selected from the group consisting of ZSM-5, ZSM-11, ZSM-22, ZSM-23, ZSM-35, ZSM-48, ZSM-57, ZSM-58, and mixtures of two or more thereof;
• (ii) 0.001 wt. % to 20.0 wt. % of at least one first metal, said first metal being in Group 6 of the Periodic Table, based on the weight of said first catalyst composition;
• and
• (iii) 0.001 wt. % to 20.0 wt. % of at least one second metal, said second metal being in Group 9 or Group 10 of the Periodic Table, based on the weight of said first catalyst composition;
• and
• b) contacting said first effluent and optionally hydrogen with a second catalyst composition under conversion conditions effective to transalkylate said remaining C8+ aromatic hydrocarbons with said C6-C7 aromatic hydrocarbon to produce a second effluent comprising said lighter aromatic products which comprises xylenes,
• wherein said second catalyst composition comprises:
• (i) a second zeolite which has a constraint index of less than or equal to 3, said second zeolite being selected from the group consisting of ZSM-4, ZSM-12, ZSM-20, ZSM-50, zeolite beta, a mordenite zeolite, a faujasite zeolite, a MCM-22 family material, MCM-68, and mixtures of two or more thereof;
• (ii) 0.001 wt. % to 20.0 wt. % of at least one first metal, said first metal being in Group 6, based on the weight of said second catalyst composition;
• and
• (iii) 0.001 wt. % to 20.0 wt. % of at least one second metal, said second metal being in Group 9 or Group 10, based on the weight of said second catalyst composition,
• wherein said first catalyst composition and/or said second catalyst composition are treated with a source of sulfur and/or a source of steam.

A catalyst system for conversion of C8+ aromatic hydrocarbons to lighter aromatic products, said catalyst system comprising:

• (a) a first catalyst bed comprising a first catalyst composition, said first catalyst composition comprising (i) a zeolite which has a constraint index from greater than 3 up to 12, said first zeolite being selected from the group consisting of ZSM-5, ZSM-11, ZSM-22, ZSM-23, ZSM-35, ZSM-48, ZSM-57, ZSM-58, and mixtures of two or more thereof;
• (ii) 0.001 wt. % to 20.0 wt. % of at least one first metal, said first metal being in Group 6 of the Periodic Table;
• and (iii) 0.001 wt. % to 20.0 wt. % of at least one second metal, said second metal being Group 9 or Group 10 of the Periodic Table, each wt. % being based on the weight of said first catalyst composition;
• and
• (b) a second catalyst bed comprising a second catalyst composition, said second catalyst composition comprising (i) a zeolite which has a constraint index of less than or equal to 3, said second zeolite being selected from the group consisting of zeolite beta, ZSM-4, ZSM-12, ZSM-20, ZSM-50, a MCM-22 family material, MCM-68, a mordenite zeolite, a faujasite zeolite, and mixtures of two or more thereof;
• (ii) 0.001 to 20.0 wt. % of at least one first metal, said first metal being in Group 6;
• and (iii) 0.001 to 20.0 wt. % of at least one second metal or compounds thereof, said second metal being in Group 9 or Group 10, each wt. % based on the weight of said second catalyst composition,
• wherein said first catalyst composition and said second catalyst composition are treated with a source of sulfur in one or more stages at temperatures in the range 204° C. (400° F.) up to about 480° C. (900° F.) or treated in one or more stages with a source of steam which comprises up to about 100% steam at temperatures in the range of about 260° C. (500° F.) to about 649° C. (1200° F.).