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

The vapor phase condensation reaction of monoethanolamine (MEA) has been ca rried out over three ZnO-modified zeolite catalysts in the temperature rang e 280-400 degreesC. Ethylpyrazine was formed as the major product in the ca ses of ZnO-ZSM-5 and ZnO-FER, whereas pyrazine was formed as the major prod uct in the case of ZnO-MOR. Moreover, we observed with ZnO-MOR a large amou nt of lower boilers which included methylamine, aziridine, ethylamine and e thylenediamine. The formation of DABCO was appreciable over ZnO-MOR; howeve r, it becomes less probable over the other two catalysts, due to their high er dehydrogenation activity. The stability of these catalyst systems in the conversion of MEA followed the order: ZnO-ZSM-5 > ZnO-MOR > ZnO-FER. (C) 2 001 Elsevier Science B.V. All rights reserved.