Xylene Isomerization Process and Catalyst Therefor

Abstract

The invention concerns a xylenes isomerization process for the production of equilibrium or near-equilibrium xylenes. The process utilizes a catalyst comprising HZSM-5 or MCM-49 and process conditions including a temperature of less than 295° C. and a pressure sufficient to maintain the xylenes in liquid phase. In embodiments, the process can be operated in a continuous mode with ppm levels of dissolved H 2 in the feed and in other embodiments in a cyclic mode without the H 2 in feed but with periodic regenerations using a feed having low ppm levels of H 2 .

1 . - 17 . (canceled) 
     
     
         18 . A catalyst comprising H-ZSM-5, further characterized by at least one of the following characteristics:
 an average crystal size of less than 0.1 microns;   a mesoporous surface area (MSA) greater than 45 m 2 /g;   a zeolite surface area (ZSA) to mesoporous surface area (MSA) ratio of less than 9;   and optionally comprising a binder.   
     
     
         19 . The catalyst of  claim 18 , further comprising a binder selected from at least one of alumina, silica, clay, and aluminosilicate. 
     
     
         20 . The catalyst of  claim 19 , in contact with a feedstream comprising C8 aromatic hydrocarbons and from 4 to 10 ppm levels of H 2 , in a reactor at a temperature below 295° C. 
     
     
         21 . The catalyst of  claim 18 , wherein said catalyst has a silica to alumina weight ratio (as SiO 2 :Al 2 O 3 ) of from 20 to 50. 
     
     
         22 . The catalyst of  claim 19 , wherein said binder is in the amount of 10 - 90 wt % based on the weight of said catalyst. 
     
     
         23 . The catalyst of  claim 18 , wherein said catalyst is formed by a method selected from extrusion, pelletization, oil dropping, or spray drying, using at least one extrusion aid selected from acetic acid. 
     
     
         24 . The catalyst of  claim 18 , having all of the following characteristics:
 an average crystal size of less than 0.1 microns;   a mesoporous surface area (MSA) greater than 45 m 2 /g; and   a zeolite surface area (ZSA) to mesoporous surface area (MSA) ratio of less than 9.