Synergistic\nPromotion of CO<sub>2</sub> Hydrate Formation\nby 1,3-Dioxolane and Sodium Lignosulfonate: A Study of Kinetic Characteristics

Capture and storage of CO<sub>2</sub> (CCS) is recognized\nas an\nimportant, urgent, and necessary option to reduce CO<sub>2</sub> emissions\nfrom the coal and oil and gas industries and to mitigate the severe\nimpact of CO<sub>2</sub> on the atmosphere and the environment. Hydrate-based\napproach is a new way to solve this challenge, but the challenge is\nhow to synthesize hydrates rapidly and increase their growth rate\nand storage capacity. In this paper, two additives, 1,3-dioxopentacycline\n(1,3-DIOX) and sodium lignosulfonate (SL-Na), were selected for experimental\nstudies of CO<sub>2</sub> hydrate trapping at different concentration\nratios, and the results showed that the two synergistically enhanced\nthe kinetic process of the hydrates under a certain concentration\nof the compound system. Molecular dynamics simulations showed that\nthe potential energy of the 1,3-DIOX + SL-Na + CO<sub>2</sub> + H<sub>2</sub>O compound system was lower than that of the other systems,\nsuggesting that a more stable CO<sub>2</sub> hydrate would be generated\nwithin this compound system. The radial distribution function shows\nthat 1,3-DIOX changes the structure of the hydrate, SL-Na enhances\nthe solubilization of CO<sub>2</sub> molecules, and the copresence\nof the two reduces the agglomeration force between CO<sub>2</sub> molecules,\nwhich facilitates the diffusion of CO<sub>2</sub> in the aqueous solution\nand the confinement of CO<sub>2</sub> in the crystalline cages, and\nthus promotes the growth of the hydrate.