Molecular insights into the synergistic inhibition mechanisms of antifreeze protein and methanol on carbon dioxide hydrate growth

• Published in: Energy (Oxford) Vol. 310; p. 133239
• Main Authors: Zhang, Yue, Yuan, Chengyang, Chen, Zherui, Chen, Cong, Liang, Xiaodong, Solms, Nicolas von, Song, Yongchen
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 30.11.2024
• Subjects: Antifreeze protein; CO2 hydrate; Flow assurance; Molecular dynamics; Synergistic inhibition; Molecular dynamics; CO2 hydrate; Synergistic inhibition; Antifreeze protein; Flow assurance
• ISSN: 0360-5442
• DOI: 10.1016/j.energy.2024.133239

The formation of CO2 hydrates during CO2 transportation and deep-sea injection poses a significant risk of pipeline blockage. Combining kinetic (KHIs) and thermodynamic hydrate inhibitors (THIs) serves as a promising efficient and economical strategy to mitigate this issue, whose performance and microscopic mechanisms yet are still poorly understood. This study employs molecular dynamics simulations to explore the effects of the combination of winter flounder antifreeze protein (wf-AFP) as a KHI and methanol as a THI on CO2 hydrate growth. We find that methanol and wf-AFP exhibit an intriguing synergistic inhibition performance on hydrate growth. In the AFP-only system, AFP serves as a spatial hindrance near the hydrate growth interface. However, in the AFP + methanol system, AFP changes its position due to the attractive force of methanol. Part of the AFP fragment remains on the hydrate interface, while the rest surrounds the CO2 droplet. Methanol, in addition to disrupting the water structure, combines with AFP to act as a double barrier to CO2 dissolution into the aqueous solution, thereby significantly reducing the gas source for hydrate growth. These findings provide molecular-level insights into hydrate inhibition mechanisms and guide the design of efficient inhibitors for safe CO2 transportation and injection. [Display omitted] •The inhibitory effect of methanol on the growth of CO2 hydrates is not significant.•Antifreeze protein prevents the growth of hydrates by adsorbing at the hydrate growth interface.•AFP and methanol can act as a double-barrier to reduce the solubility of CO2.•The strength of the synergistic effect is related to the concentration of methanol.