Branched sulfonated promoter: Achieving high methane uptake and foam-free gas recovery for solidified gas storage

Abstract

Gas hydrates offer a promising solution for clean and low-carbon energy storage and the transportation of natural gas. However, their slow formation kinetics and dissociation-induced foaming hinder their practical application. This study investigates a novel branched sulfonated promoter (BSP) to address these challenges. The effectiveness of BSP in promoting methane hydrate formation was evaluated by measuring the conversion degree, methane consumption, storage capacity, hydrate growth rate, and reaction rate constant. Molecular dynamics (MD) simulations provided insights into BSP's interaction with methane and water molecules, its self-aggregation, adsorption, and its role in hydrate cage formation. BSP demonstrated comparable performance to SDS in accelerating methane hydrate formation. At a concentration of 500 ppm, BSP achieved a water-to-hydrate conversion rate of 89.54 %, methane consumption of 432.16 mmol, and a storage capacity of 165.1 v/v after 450 min. BSP effectively suppressed foam formation during methane hydrate dissociation, and all the hydrates melted within 15 min. Moreover, BSP promotes the formation of dense and solid hydrates, unlike SDS, which favors hydrate growth on reactor walls. MD simulations revealed that BSP molecules do not form micelles but interact with water molecules through their hydrophilic chains, facilitating methane accumulation around their hydrophobic tails. This behavior promotes methane aggregation and hydrate formation. BSP surpasses SDS in terms of foam-free dissociation, making it a promising candidate for practical hydrate-based energy storage and transportation technologies. The combined experimental and computational approach provides valuable insights into the mechanisms underlying BSP's promotional effect, challenging the long-held belief that long alkyl chains are essential for hydrate promotion. This paves the way for further development of effective and environmentally friendly hydrate promoters.