Isopropylation of benzene with propene on high-temperature chlorine-treated alumina catalysts

Isopropylation of benzene with propene on alumina, solid Lewis superacid, A mLSA, treated in dry chlorine at 1073 K was studied using a semi-batch reac tor (for liquid-phase catalytic reaction) and a fixed bed flow reactor (for vapor-phase catalytic reaction) under atmospheric pressure at 303 K and 30 3-623 K, respectively. In the liquid-phase reaction, the products were isop ropylbenzene (IPB), di-isopropylbenzenes (di-IPB). and tri-isopropylbenzene s (tri-IPB). The dissolution of active species from the catalyst into the o rganic medium was not observed. Since propene adsorption resulted in the fo rmation of isopropylidene and 2-propylene cations, the isopropylation seeme d likely to proceed through the interactions involving these cations and be nzene pi-complex. Addition of sodium to the catalyst accelerated the format ion of higher substituted benzenes and increased meta-para ratio of di-IPB. in the vapor-phase reaction, tetra-isopropylbenzene (tetra-IPB) was also f ormed, and the formation of di-, tri-, and tetra-IPB was promoted more at t emperatures below 473 K than in the liquid phase reaction. With increase in the benzene-propane ratio in the feed gases, the selectivity to all substi tuted benzenes on the basis of consumed propene increased Furthermore, at a ll reaction temperatures, origomerization of propene deactivated the cataly st.