A comparative study on the catalytic activity of ZnO modified zeolites in the synthesis of alkylpyrazines Original Research Article

The vapor phase condensation reaction of monoethanolamine (MEA) has been carried out over three ZnO-modified zeolite catalysts in the temperature range 280–400°C. Ethylpyrazine was formed as the major product in the cases of ZnO–ZSM-5 and ZnO–FER, whereas pyrazine was formed as the major product in the case of ZnO–MOR. Moreover, we observed with ZnO–MOR a large amount of lower boilers which included methylamine, aziridine, ethylamine and ethylenediamine. The formation of DABCO was appreciable over ZnO–MOR; however, it becomes less probable over the other two catalysts, due to their higher dehydrogenation activity. The stability of these catalyst systems in the conversion of MEA followed the order: ZnO–ZSM-5>ZnO–MOR>ZnO–FER.