MULTIPLICITY IN REACTIVE DISTILLATION OF MTBE

This paper presents an explanation of why Metyl tert-Butyl Ether (MTBE ) production by reactive distillation may yield multiple solutions. Wi dely different composition profiles and conversions may, as already re ported by Krishna and others, result with identical column specificati ons, depending on the initial estimates provided, A hypothesis yieldin g a qualitative understanding of this phenomenon has been developed. T he inert n-butene plays a key role in the proposed explanation: As the reaction mixture is diluted with n-butene, the activity coefficient o f methanol increases substantially and the temperature decreases. This dilution has a pro-found effect on the equilibrium conversion, enabli ng MTBE to escape from the reactive zone without decomposition, When m ethanol is fed below or in the lower part of the reactive zone of the column, the ''lifting-capacity' of the minimum-boiling point MTBE/meth anol azeotrope will also be important,