Dual-loop xylene isomerization process

摘要

A method for increasing the efficiency of xylene isomerization by using a two stage isomerization process. In the first stage of the process, a C9+ aromatics feedstock is subjected to ethylbenzene conversion and xylene isomerization. Non-C8 aromatics are removed from the effluent, which is then processed in a second stage of the process to remove para-xylene and isomerize the para-xylene depleted effluent. The effluent from the second stage isomerization unit is then recycled into the inlet of the second stage of the process and a slip stream from the para-xylene separator is recycled to the feedstock and to the effluent of the ethylbenzene conversion unit. In this way, the production of para-xylene is maximized. In a preferred embodiment, toluene is co-fed into the feedstock to minimize the loss of xylenes during the ethylbenzene conversion reaction.