Understanding CO2 absorption by an ammonium-based ionic liquid confined in porous carbon material under applied voltage

RG Pereira and VO Valente and RM de Souza and LJA Siqueira, JOURNAL OF MOLECULAR LIQUIDS, 366, 120227 (2022).

DOI: 10.1016/j.molliq.2022.120227

Mitigation of global warming will be possible by using low carbon energy generation in tandem with CO2 capture and/or storage. Although CO2 absorption by amines is highly efficient, it is rather energy-consuming to regenerate the amine. Capture/storage of CO2 by membranes arises as an alternative method as they require low energy in the recovering process, but suffer from low gas permeability. External stimuli, such as increase of temperature and the application of voltage, are an interesting alter-native to improve membrane performance. Here, we performed molecular dynamics simulations of an ammonium-based ionic liquid, butyl-trimethyl-ammonium bis(trifluoro-methane-sulfonyl) imide (N-1114NTf2), confined in porous carbons with different pore sizes under application of voltage, as membrane material for CO2 absorption/capture. The imbalance of ions inside the pores imposed by the voltage, for instance, the higher number of NTf2(- )in the positive electrode, increases not only the number of CO2 within the pores but also the rate CO2 is absorbed in the bulk due to favorable interactions of CO2 with NTf2(-) anions. Increasing the pore size (from 1.2 to 1.5 nm), the ions' mobilities increase, which yields faster gas uptake. The improvement of gas solubility inside the pores and the faster uptake under applied voltage is a result of the ions' mobility within the pores, the available free volume, and favorable gas-anion interaction within the positively charged pores. (c) 2022 Elsevier B.V. All rights reserved.

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