Process Analysis for Dimerization of Isobutene by Reactive Distillation

Alkylates are a class of probable replacements for MTBE as gasoline additives that can be produced by dimerization of isobutene (to isooctene) with subsequent hydrogenation. The characteristics of the dimerization reaction make it a potential candidate for reactive distillation. The dimer, being heavier than C4, can be maintained at a low concentration level in the reactive zone by simultaneous distillation, thereby suppressing the subsequent oligomer-producing reactions. In this work, the influence of important design and operating parameters on the performance of the reaction in a hybrid reactive distillation column is studied through process simulations. the results show that a high selectivity toward diisobutene can be achieved along with adequate temperature control in the presence as well as absence of polar components. Multiple steady states are observed in some cases that introduce additional complexities in the determination of the optimal windows for certain parameters. The process seems economically attractive, as it is capable of utilizing the existing reactive distillation assets and the feedstock for MTBE production by suitable revamping.