Capturing renewable isobutanol from model vapor mixtures using an all-silica beta zeolite

Abstract

[EN] Isobutanol is a promising renewable platform chemical, produced via fermentation. In the conventional downstream processing, isobutanol is recovered from the fermentation broth via evaporation or gas-stripping, followed by purification via distillation. Alternatively, an adsorptive separation can be used to recover isobutanol from the generated vapor mixture, however this has remained unexplored in the literature. In this work, we investigate the use of a hydrophobic all-silica beta zeolite (Si-BEA) to recover isobutanol from model vapor mixtures via adsorption. The Si-BEA zeolite shows a high selectivity for isobutanol over water (? = 35) and ethanol (? = 10) and excellent mass transfer properties under dynamic conditions. Sharp isobutanol breakthrough profiles were obtained, leading to a fraction of unused bed of only 6% at a gas residence time of only 0.6 s. The adsorbed isobutanol could be fully desorbed via thermal regeneration and an isothermal purge allows to remove co-adsorbed ethanol and water. The results of this work thus show the promising properties of Si-BEA for the recovery of renewable isobutanol from vapor mixtures.