Abstract: The stability with time-on-stream of NaBr-promoted KY zeolite catalyst for the oxidative methylation of toluene with methane has been investigated. The results showed that during 50 h of reaction, the toluene conversion and the total C8 selectivity decreased fast at the first and then basically remained unchanged, they kept at about 35％ and 65％－70％ respectively. The selectivity of styrene decreased while the selectivity of ethyl benzene increased during the reaction process. This result was ascribed to the estimation that the styrene was formed by the dehydrogenation of ethyl benzene and the dehydrogenation activity decreased in the reaction process. In addition, the structure of the catalyst used was also studied by XRD, IR and XPS. It was found that the zeolite catalyst suffered dealumination, elimination of KBr and partial destruction of structure but the zeolite framework still retained.

Key words: KY zeolite, Toluene, Methane, Oxidative methylation, Stability