Viable hydrate-based CO2 capture facilitated by cyclopentane hydrate seeds and tailored kinetic promoters

Abstract

With the increasing demand for scalable carbon capture technologies, environmentally benign clathrate hydrate-based systems have gained attention. However, unpredictable nucleation delays, slow hydrate formation kinetics, and reliance on energy intensive agitation methods have impeded industrial adoption of CO2 hydrates. This study reports significantly high CO2 uptakes of 0.1503 mol CO2/mol H2O for structure I (sI) CO2 hydrates and 0.0693 mol CO2/mol H2O for structure II (sII) cyclopentane (CP)-CO2 hydrates under static conditions. Critically, the introduction of hydrate seeds and specifically tailored kinetic promoters lead to instantaneous nucleation, an occurrence not previously reported. Our findings, supported by kinetic analyses and molecular dynamics simulations, reveal that sodium alkyl sulfate, which is effective in various hydrate systems including natural gas storage, inhibited sI CO2 hydrate formation under static conditions due to interference by its long alkyl chains with CO2 interactions. In contrast, moderate hydrophobic amino acids, particularly L-methionine, significantly enhanced hydrate formation kinetics through optimal interactions with CO2 molecules. Ex-situ and in-situ Raman spectroscopy confirmed that in sII CP-CO2 systems, the use of L-methionine resulted in high CO2 uptake due to co-enclathration of CO2 and CP molecules, whereas the surfactant molecules reduced CO2 storage capacity by promoting rapid pure CP hydrate growth. These results offer critical guidelines for promoter selection and significantly advance the industrial viability of hydrate-based CO2 capture technologies. © 2025 Elsevier B.V.