para-Xylene from Toluene and Methanol

This review examines the economics of para-xylene synthesis by the selective alkylation of toluene with methanol in a zeolite catalyzed reaction system. The data used in our evaluation were extracted from the published work of Mobil Chemical Company, who have been the most active in this area. For the process concept assumed by SRI, the economics of para-xylene by the alkylation route are markedly inferior to the economics of production from reformate xylenes mixture by a Parex�/Isomar� (UOP) combination. We judge that the main factors responsible for the unfavorable showing of the synthetic route are the low toluene conversions (~20%) and the poor methanol selectivities (~40%), as evidenced by the published data.