Published April 1990
Mobil's High Temperature Isomerization (MHTI) process uses a platinized acidic zeolite ZSM-5 to isomerize a p-xylene depleted C8 aromatics stream to a product mixture having a p-xylene concentration greater than its equilibrium value. Simultaneously, ethylbenzene and non-aromatics in the feed are converted to benzene and light paraffins, respectively. The high performance of this catalyst leads to a low hydrogen circulating rate and a small size of reactor. Commercially, the isomerization is operated in conjunction with a p-xylene recovery facility. In this review, the Parex� process is used as the recovery facility for the purpose of comparing the isomerization processes and the combined process is denoted the Parex�/MHTl process. We evaluate the Parex�/MHTI process and compare its economics with that of UOP's Parex�/lsomar� process updated from PEP Report 182 (June 1987). SRI concludes that the Parex�/MHTl process require slower total fixed capital than does the Parex�/lsomar� process. The production costs generally favor the Parex�/MHTI process, especially when the higher aromatics by-product credits are considered.
