SOLID BASE CATALYSTS FOR SIDE-CHAIN ALKYLATION OF TOLUENE WITH METHANOL

A wide variety of solid bases, including alkali-exchanged zeolites X, Y, L and beta, and alkali-impregnated carbon and magnesia, were tested as catalysts for the side-chain alkylation of toluene with methanol t o form styrene and ethylbenzene. In addition, the effects of adding Gr oup ILIA elements (B, Al, Ga, In) to the catalysts were examined. At 6 80 K and atmospheric pressure, the major reaction products were styren e, ethylbenzene, and carbon monoxide. Cesium-exchanged zeolite X was t he most effective alkali-containing catalyst for the alkylation reacti on. Of the Group IIIA additives that were tested, only boron promoted the alkylation reaction. The primary effect of adding boron was to red uce the decomposition of methanol to carbon monoxide. Apparently, boro n selectively modifies the sites associated with methanol decompositio n without inhibiting the sites active for alkylation. A berated Cs-car bon sample also catalyzed the alkylation reaction, demonstrating that a zeolite framework is not necessary to form the active site. Micropor osity seems to play an important role in these catalysts since both th e alkali-modified carbons and the zeolites are microporous.