Comparing the Kinetic Inhibition Performance of Various Polymeric, Ionic Liquid and Polysaccharide Additives in Methane-Water System

Hydrate formation is one of the key challenges constraining the safe and efficient development of offshore natural gas. Kinetic hydrate inhibitors (KHIs) represent one of the effective solutions for hydrate prevention and control. This study employed a high-pressure rocking cell reactor to measure the inhibition efficacy of various KHIs, including polymers, polysaccharides, and ionic liquids, on hydrate formation in CH4-water systems. PVP demonstrated superior hydrate inhibition performance compared to LuviCap. At concentrations of 0.1 wt% and 0.25 wt%, the induction times for PVP were 4.98 h and 5.6–6.13 h, respectively, and the subcooling degrees were 5.27 K and 5.77–5.98 K, respectively. Sodium alginate, sodium carboxymethyl cellulose, polypropylene glycol, and chitosan exhibited stronger inhibition effects on hydrate formation than gum arabic, tetrapropylammonium hydroxide, and carboxymethyl chitosan. The induction times (2.1–4.4 h) and subcooling degrees (2.5–5.1 K) for gum arabic, tetrapropylammonium hydroxide, and carboxymethyl chitosan were relatively low. In contrast, sodium alginate, sodium carboxymethyl cellulose, polypropylene glycol, and chitosan showed significantly increased induction times (7.35–10.04 h) and subcooling degrees (5.52–7.88 K) compared to the former three inhibitors. Based on the experimental results, the mechanism of KHIs was discussed. The synergistic action of two mechanisms – inhibitors occupying growth sites through hydrogen bonding adsorption and hindering surface expansion via steric hindrance – can effectively inhibit the growth of hydrate crystals.