Xylenes Isomerization

This review compares the economics of UOP's Isomar process and Mobil's MHAI (Mobil High Activity Isomerization) process, both of which produce p-xylene from catalytic reformate but employ different methods for doing so. MHAI achieves higher ethylbenzene conversion and a closer approach to p-xylene thermodynamic equilibrium, but diverts a higher proportion of ethylbenzene to nonxylene products. The Isomar process isomerizes ethylbenzene to xylenes, but does so at lower conversion levels and lower approaches to p-xylene equilibrium. These process differences result in significant differences in utility costs, by-product credits, and fixed capital requirements.