Comparison Study on the Practicality of Amino Acid Usage in Rapid Hydrate Formation of CO ₂ + CH ₄ Gas Mixture

In recent years, amino acids have garnered attention for their potential roles as thermodynamic inhibitors and kinetic promoters in gas hydrate formation. This study investigates and compares the effects of arginine, leucine, CTAB (cetyltrimethylammonium bromide), and ZnO nanoparticles on the thermodynamic and kinetic behavior of gas hydrate formation using a 50:50 mol % methane–carbon dioxide mixture in a stirred reactor under high agitation and severe low-temperature conditions. Thermodynamic analysis revealed that none of the tested additives, whether amino acids or nanoparticles, had a significant impact on the hydrate phase equilibrium. Kinetic results showed that within the tested concentration range (0.5–1.5 wt %), arginine resulted in greater gas uptake than leucine. ZnO nanoparticles did not form a stable nanofluid and showed minimal kinetic enhancement when used alone. CTAB significantly accelerated gas consumption rates, achieving maximum gas uptake in one-third of the time compared to arginine. The mixture of 0.10 wt % ZnO with 0.05 wt % CTAB formed a nanofluid that resulted in the best performance, surpassing all other additives in both gas consumption rate and quantity. These findings suggest that at low concentrations, the tested amino acids are ineffective as thermodynamic inhibitors. As kinetic promoters, their performance is inferior to that of the surfactant-stabilized nanofluid.