Thermodynamic and molecular insights into the absorption of H₂S, CO₂, and CH₄ in choline chloride plus urea mixtures

Abstract

Deep eutectic solvents (DESs) are a class of promising media for gas separation. In order to examine the potential application of DESs for natural gas upgrading, the solubilities of H2S, CO2, and CH4 in choline chloride (ChCl) plus urea mixtures were measured in this work. The solubility data were correlated with Henry's law equation to calculate the thermodynamic properties of gas absorption processes, such as Henry's constants and enthalpy changes. Grand‐canonical Monte Carlo simulations and quantum chemistry calculations were also performed to examine the mechanism of gas absorption processes. It is found that the absorption of H2S in ChCl + urea mixtures is governed by the hydrogen‐bond interaction between Cl of ChCl and H of H2S, whereas the absorption of CO2 and CH4 in ChCl+urea mixtures is governed by the free volume of solvents. Based on the different behavior of gas absorption, high H2S/CO2, H2S/CH4, and CO2/CH4 selectivities can be achieved by adjusting the ratio of ChCl/urea in mixtures.

Promoted absorption of CO at high temperature by cuprous‐based ternary deep eutectic solvents

“…Thus, DESs are widely regarded as a new class of IL analogues. Many previous studies have demonstrated the applications of DESs in the absorption of CO 2 , 14 NH 3 , 15,16 and H 2 S 17 . Up to now, there has been less mention of using DESs for efficient absorption of CO.…”

CO2‐Philic Separation Membrane: Deep Eutectic Solvent Filled Graphene Oxide Nanoslits

“…Since the research to date on the application of DESs for CO 2 capture has been restricted to the gas adsorption, solubility, and other physicochemical properties of DESs, further more systematic explorations into the mechanism of CO 2 ‐DES system and attempts at the DESs‐based CO 2 separation membrane fabrication have remained to be made . To the best of our knowledge, the rollout and the only report of DES‐based membrane so far for the purpose of CO 2 separation was polyvinylidene fluoride‐ co ‐polytetrafluoroethylene/DES supported membrane prepared by incorporation of choline chloride/ethylene glycol (ChCl/EG) DES into polymeric membrane pores and achieved a CO 2 permeance of 25.5 × 10 3 GPU (gas permeation unit, 1 GPU = 1 × 10 −6 cm 3 (STP) cm −2 s −1 cmHg −1 ) but with separation factor of only 2 .…”

Utilization of Deep Eutectic Solvents to Reduce the Release of Hazardous Gases to the Atmosphere: A Critical Review

“…Liu et al [ 124 ] found that H 2 S absorption capacity increased with increasing molar ratio of ChCl/urea DES from 1:1.5 to 1:2.5 at a fixed temperature and pressure. Furthermore, the absorption capacity of H 2 S in ChCl/urea DESs was decreased linearly by increasing the temperature.…”