CO2 Capture from CO2 + H2 Gas Mixture Using Tetra-n-butyl Ammonium Chloride Semiclathrate

Abstract

In this study, tetra-n-butyl ammonium chloride (TBAC) was used for semiclathrate formation. TBAC forms semiclathrate with water under atmospheric pressure. TBAC semiclathrate has small vacant cages which can be used for capturing small-sized gas molecules, while large cages of TBAC semiclathrate are occupied by TBA cations. TBAC semiclathrate is most stable at 3.3 mol%, which is a stoichiometric concentration. This study is focused on the selective CO2 separation from the pre-combustion fuel gas mixture using TBAC semiclathrate. The phase equilibria showed that the TBAC semiclathrate with CO2 + H2 was significantly stabilized when compared with pure gas hydrate. The enclathration of guest molecules in the small cages was confirmed via in-situ Raman spectroscopy. The gas uptake of TBAC semiclathrate in the presence of hollow silica and solid silica was higher than that of TBAC semiclathrate without silica particles. The CO2 concentration in the semiclathrate phase was found to be approximately 90 %. Through the experimental results obtained in this study, TBAC semiclathrate is expected to be a good candidate material for CO2 separation from pre-combustion fuel gas mixtures.