Kinetic and Macroscopic Growth of Methane Hydrate Formation in Maltodextrin–Amino Acid Composite Systems

With the continuous growth of global energy demand, natural gas, as a clean fuel, has drawn people's attention, and natural gas hydrates, as a storage technology for natural gas, have also attracted much attention. However, the industrialization of natural gas hydrates is confronted with the slow formation kinetics of methane hydrates and the adverse environmental impacts caused by the extensive use of chemically synthesized surfactants. To overcome these difficulties, current research is focused on developing environmentally friendly green accelerators. In this experiment, maltodextrin, a biosurfactant, was utilized as a primary promoter to bind with methionine and phenylalanine, achieving a synergistic effect. The results indicated that maltodextrin significantly improved the slow formation kinetics of hydrates, and its promoting effect was closely related to the concentration. When the optimal concentration is 1000 ppm, the maximum gas storage capacity of the hydrate increases by 554.6% compared with the pure water system. Compared with the phenylalanine-maltodextrin complex system, the methionine-maltodextrin complex system has a better effect in promoting the formation of hydrates. The combination study of maltodextrin and two amino acids shows that 1000 ppm maltodextrin combined with 2000 ppm phenylalanine can shorten the hydrate induction time to 4.5 min (a reduction of 98.2% compared with the pure water system). The combination of 1000 ppm maltodextrin and 1500 ppm methionine increases the final gas storage capacity to 135.2 v/v (435.9% higher than the pure water system). It is worth noting that maltodextrin concentrations between 500 and 1000 ppm exhibit the best promoting effect. This series of research not only provides green and feasible solutions for addressing the dynamic bottlenecks and environmental risks of natural gas hydrate technology, but also offers significant support for achieving safer, more stable, and more environmentally friendly industrial applications of natural gas hydrates.