Isopropylation of Xylenes Catalyzed by Ultrastable Zeolite Y (USY) and Some Other Solid Acid Catalysts

The isopropylation of all three xylene isomers was carried out over ultrastable zeolite Y (USY) catalyst to give corresponding dimethyl (1-methylethyl) benzenes, or in other words dimethyl cumenes (DMCs), using isopropanol as alkylating agent. The effect of reaction temperature, space velocity, substrate-to-alkylating-agent molar ratio, and time-on-stream on conversion of xylene isomers and selectivity to dimethyl cumene was studied. Isopropylation of xylenes over USY gives quite high (80 to 95%) DMC selectivity among the dimethyl cumenes, along with a 70–90% yield of DMCs in total products with respect to limiting reagents, i.e., isopropylating agents at relatively low reaction temperatures (423±10 K) and at quite high xylene conversions (85–97% of theoretical maximum value). The solid acid catalysts zeolites H–Y, H-beta, H–mordenite, as well as silica–alumina and sulfated zirconia, were included for comparative studies in the isopropylation of m-xylene.