摘要 |
Catalysts comprising a crystalline zeolite of constraint index in the range of 1 to 12 are known to exhibit high selectivity to para-substituted products and processes such as xylene isomerisation, particularly when they manifest certain xylene sorption characteristics. According to the invention this selectivity is maintained or enhanced by regenerating such catalysts, when deactivated by deposition of coke during use, in a hydrogen - instead of an oxygen - containing atmosphere under specified conditions. |