Selective absorption of H2S and CO2 by azole based protic ionic liquids: A combined density functional theory and molecular dynamics study

Abdul Rajjak Shaikh, Sergio Posada-Pérez, Artur Brotons-Rufes, Jason J. Pajski, Vajiha, Gulshan Kumar, Ayesha Mateen, Albert Poater, Miquel Solà, Mohit Chawla, Luigi Cavallo

Research output: Contribution to journalArticlepeer-review

17 Scopus citations


To achieve efficient carbon capture, utilization, and storage, it is necessary to separate CO2 from the atmosphere. In an attempt to move towards selective separation of CO2, some of us have shown that ionic liquids (ILs) can be efficiently used to separate CO2 and H2S from CH4 and H2O. In the present work, we perform Density Functional Theory and Molecular dynamics simulations for four different ILs: [DBNH][1,2,3-triaz], [DBNH][1,2,4-triaz], [DBUH][1,2,3-triaz] and [DBUH][1,2,4-triaz]. DFT calculations have unveiled the additional selective character of H2S with respect to CO2. Whereas CO2 binds to the nitrogen of the anionic moiety of the IL forming a new C[sbnd]N bond, H2S transfers a proton to one of the nitrogen atoms of the IL with the consequent generation of a HS- anion. Radial distribution function analysis shows the presence of hydrogen bonds between cation and anion in neat ILs as well in presence of gases. Hydrogen bond analysis shows higher number of hydrogen bonds in the ILs between cation and the [1,2,3-triaz] anion as compared to [1,2,4-triaz] anion. Molecular dynamics simulations also show that these ionic liquids have stronger interaction with CO2 and H2S as compared to CH4. Overall, our study confirms the usage of studied ILs to efficiently capture CO2 and H2S.
Original languageEnglish (US)
Pages (from-to)120558
JournalJournal of Molecular Liquids
StatePublished - Oct 20 2022

Bibliographical note

KAUST Repository Item: Exported on 2022-10-31
Acknowledgements: Authors would like to thank the King Abdullah University of Science and Technology (KAUST) Supercomputing Laboratory (KSL) for providing the necessary computational resources. A.P. is a Serra Húnter Fellow and ICREA Academia Prize 2019. S.P.P thanks the Spanish Ministerio de Ciencia e Innovación for Juan de la Cierva Formación fellowship (FJC2019-039623-I) and Marie Curie fellow (H2020-MSCA-IF-2020-101020330). M.S. thanks the Spanish MINECO for project PID2020-13711 GB-I00 and A.P. the Ministerio de Ciencia e Innovación for project PID2021-127423NB-I00, and the Generalitat de Catalunya for project 2017SGR39. S.P.-P. A.B.-R. J.J.P. V. G.K. and A.M. thank STEMskills Research and Education Lab Private Limited, India for providing supervision within the workshop ‘MD simulations of Ionic Liquids’.

ASJC Scopus subject areas

  • Materials Chemistry
  • Spectroscopy
  • Atomic and Molecular Physics, and Optics
  • Physical and Theoretical Chemistry
  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics


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