Oxidative methylation of toluene with methane catalyzed by cesium modified molecular sieves Original Research Article

Cesium exchanged zeolites (X, Y, and ZSM-5) and cesium impregnated molecular sieve AlPO4-5 were studied as catalysts for oxidative methylation of toluene with methane. The effects of structure and basicity were examined. XRD analysis indicated that in the exchanged zeolites, cesium was finely dispersed while in the impregnated molecular sieve a CsCl phase was obtained. IR spectroscopy was more informative than XRD analysis as regards the crystallinity of the catalysts after modification with cesium. The most appropriate structure for the best selectivity and yield of ethylbenzene+styrene was found to be that of CsAlPO4-5. A uniform distribution of the CsCl phase in accessible sites of the crystal lattice of CsAlPO4-5 was assumed. It was established that the best catalyst CsAlPO4-5 possessed weak basic sites. The performance of the basic sites was related both to the crystallographic structure and to cesium location.