Vapour phase alkylation of ethylbenzene with t -butyl alcohol over mesoporous Al-MCM-41 molecular sieves |
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Authors: | Vumamaheswari M Palanichamy Banumathi Arabindoo and V Murugesan |
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Institution: | (1) Department of Chemistry, Anna University, 600 025 Chennai, India |
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Abstract: | The alkylation of ethylbenzene witht-butyl alcohol was studied over Al-MCM-41 (Si/Al = 50 and 90) and Al, Mg-MCM-41 (Si/(Al+Mg) = 50) in the vapour phase from
200 to 400°C. The products werep-t-butylethylbenzene (p-t-BEB),p-t- butylvinylbenzene (p-t-BVB) andm-t-butylethylbenzene (m-t-BEB). Ethylbenzene conversion decreased with increase in temperature and increase in the ethylbenzene content of the feed.
The reaction between the freely diffusing ethylbenzene in the channel and thet-butyl cations remaining as charge compensating ions yieldedp-t- BEB.p-t-BVB, an unexpected product in this investigation, was produced by dehydrogenation ofp-t-BEB over alumina particles present in the channels of the molecular sieves. Adsorption of ethylbenzene on Br?nsted acid sites
and its subsequent reaction with very closely adsorbedt-butyl cations proved to be necessary to obtainm-t-BEB. Thoughm-t-BEB was obtained, the correspondingm-t-butylvinylbenzene was not observed in this study. Study of time durations indicated rapid and slow catalyst deactivation
at lower and higher streams respectively. |
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Keywords: | Mesoporous molecular sieves Al-MCM-41 ethylbenzene t-butylation t-butyl alcohol |
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