<i>Para-</i>selective<i> </i>ethylation of <i>t</i>-butylbenzene with diethyl carbonate over mesoporous molecular sieves

Abstract

The vapour phase ethylation of <i>t</i>-butylbenzene (<i>t</i>-BB) with diethyl carbonate has been studied over mesoporous Al-MCM-41 (Si/Al = 50 and 90) and Al , Mg-MCM-41 [Si /(Al+Mg) = 50] from 200 to 400°C. The products are benzene, ethylbenzene (EB), <i>p</i>-diethylbenzene (<i>p</i>-DEB), <i>p</i>-<i>t</i>-butylethylbenzene (<i>p</i>-<i>t</i>BEB) and <i>p</i>-<i>t</i>-butylvinylbenzene (<i>p-t</i>BVB) .<i>t</i>-Butylbenzene conversion increases with increase in temperature up to 300°C, but above this temperature it decreases.<i>Ortho </i>and <i>meta</i>-products are completely absent. Ethylbenzene is the product of ethylation of benzene and cracking of <i>pt</i>BEB.The selectivity of <i>para-t</i>-butylated products is favoured at lower temperature while higher temperature favours ethylbenzene selectivity. The influence of time on stream is examined over Al-MCM-41 (50) and the results are discussed in this paper.