MULTIPLICITY IN REACTIVE DISTILLATION OF MTBE

This paper presents an explanation of why methyl tert-butyl ether (MTB E) production by reactive distillation may yield multiple solutions. W idely different composition profiles and conversions may, as already r eported by Krishna and others, result with identical column specificat ions, depending on the initial estimates provided and the VLE models b eing used. A hypothesis yielding a qualitative understanding of this p henomenon has been developed. The inert n-butene plays a key role in t he proposed explanation. As the reaction mixture is diluted with n-but ene, the activity coefficient of methanol increases substantially and the temperature decreases. This dilution has a profound effect on the equilibrium conversion, enabling MTBE to escape from the reactive zone without decomposition. The minimum boiling point azeotrope between MT BE and methanol plays an important role in the internal transport mech anism for the heavy methanol, in particular when fed below or in the l ower part of the reactive section. (C) 1995 Elsevier Science Ltd.