Effects of nanoparticle, microparticles and silica sand on CO2 and CH4 gas hydrates phase equilibria

• Investigation of phase equilibrium conditions of methane (CH 4 ) and carbon dioxide (CO₂) hydrates, targeting CH 4 for energy storage and CO₂ for carbon capture and geological storage. • New phase equilibrium data were obtained for CO₂ and CH₄ gas hydrates in the presence of CuO and Al₂O₃ nanoparticles as well as graphene nanoplatelets. • Utilization specifically of silica sand porous media systems to generate new gas hydrate phase equilibria data with CO₂ and CH 4 gases. • Study of hydrate phase behaviour involving graphite powder, magnesium nitrate hexahydrate (MgN₂O₆·6H₂O), and zinc oxide (ZnO)microparticles. • Application of sodium dodecyl sulfate (SDS) as a kinetic promoter in phase equilibrium measurements. Gas hydrates present significant potential for gas storage applications, particularly when different additives are employed to enhance their efficacy. With carbon dioxide (CO 2 ) gas hydrates the main focus is on gas capture and storage in geological landforms while methane (CH 4 ) gas hydrates have been eye-marked for energy storage. To effectively utilize gas hydrates across various sectors, it is essential to understand the phase equilibrium conditions for each system, including those involving CH 4 /CO 2 and various additives. Nanoparticles enhance the formation rate of gas hydrates and show promising potential for gas storage applications. In this study, phase equilibrium conditions of CO 2 and CH 4 hydrates in the presence of CuO and Al 2 O 3 nanoparticles, graphene nanoplatelets, graphite powder, magnesium nitrate hexahydrate MgN 2 O 6 .6H 2 O, ZnO microparticles, sodium dodecyl sulfate (SDS) and silica sand were measured, experimentally. The measured temperature and pressure conditions for CH 4 hydrate systems were 277.72 to 283.03 K and 4.907 to 7.77 MPa respectively. While for CO 2 hydrate systems, the measured temperature and pressure were 279.11 to 283.73 K and 3.395 to 5.52 MPa, respectively. Results showed that for both CH 4 and CO 2 hydrate systems, the nanoparticles and powders acted as the thermodynamic inhibitor by shifting the hydrate phase equilibrium to the higher pressure and lower temperature conditions. But their inclusion in the system increased the rate of hydrate formation by decreasing the hydrate formation time. Silica sand exhibited inhibitory behaviour within specific temperature and pressure ranges, while in other conditions, it served as a promoter for CO₂ and CH₄ hydrate systems.