WHY METHYL TERT-BUTYL ETHER PRODUCTION BY REACTIVE DISTILLATION MAY YIELD MULTIPLE SOLUTIONS

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. A hypothesis yieldi ng a qualitative understanding of this phenomenon has been developed, The inert n-butene plays a key role in the proposed explanation: As th e reaction mixture is diluted with n-butene, the activity coefficient of methanol increases substantially and the temperature decreases. Thi s dilution has a profound 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-met hanol azeotrope will also be important.