Multistage inhibition mechanism of L-aspartic acid polymerized hydrate inhibitor: A combined study of molecular simulation and experimental investigation

The development of efficient and environmentally friendly hydrate inhibitors is crucial for advancing methane hydrate exploitation. However, existing inhibitors often suffer from poor biodegradability, low inhibition efficiency, and short action duration, limiting their practical application. In this study, a copolymer of L-aspartic acid and N-vinylpyrrolidone (NVP-ASP) was synthesized and evaluated as a novel kinetic hydrate inhibitor. Experimental results show that NVP-ASP extends the induction time by 66.55 % and reduces the hydrate formation efficiency by 7.98 % compared to the commercial inhibitor polyvinylpyrrolidone (PVP). Molecular simulations further elucidate its multi-stage inhibition mechanism. During nucleation, NVP-ASP effectively restricts the mobility of surrounding water and methane molecules, with an average of 13.13 water and 13.45 methane molecules adsorbed within 5 Å. During the growth stage, NVP-ASP exhibits strong anti-agglomeration behavior, significantly suppressing the formation of hydrate cages. The growth rates for simple (5 12 ) and complex (5 12 6 2 ) cages are reduced to 61.54 % and 50 %, respectively, much lower than the corresponding values for PVP (166.67 % and 233.33 %). Moreover, NVP-ASP shows low inclusion tendency into forming hydrate cages, resulting in prolonged inhibition. These findings provide mechanistic insights into hydrate formation and offer a promising strategy for designing high-performance kinetic inhibitors.