Removal of gaseous acetic acid using ionic liquid [EMIM][BF4]

Abstract

This work proposed to use the ionic liquid [EMIM][BF4] as absorbent for the absorption of gaseous acetic acid. The feasibility of this technology was investigated from molecular level to industrial scale. The acetic acid absorption experiment was carried out using [EMIM][BF4], and the removal ratio of acetic acid in the gas product can achieve 88.6% at 20 °C under atmospheric pressure at the laboratory scale. Based on the experimental results, a reliable strict equilibrium phase model embedding the parameters of the UNIFAC model was established. On this basis, the conceptual process design and optimization of acetic acid removal by [EMIM][BF4] at an industrial scale was done, and the most suitable design and operation parameters were obtained. For a further step, the binding energy between [EMIM][BF4] and acetic acid was calculated to give some insights into the separation mechanism, and the results indicate that the interaction between acetic acid and IL is much stronger than that between nitrogen and IL. Moreover, hydrogen bond can be formed between the cation-acetic acid as well as the anion-acetic acid. Keywords: Ionic liquid (IL), Gaseous acetic acid, Absorption, Process simulation, Separation mechanism