Improvement of gas hydrate-based CO2 capture from CH4/CO2 mixture using silica and modified silica nanoparticles in the presence of potassium hydroxide

Separation of CO2 gas from CO2/CH4 mixture (74 mol% of CH4 and 26 mol% of CO2) was investigated, experimentally using the gas hydrate formation method in a constant-volume vessel. Silica and (3-aminopropyl) teriethoxysilane (APTES) surface-modified silica nanoparticles in the presence of potassium hydroxide were employed as additives. The impacts of various parameters such as initial pressure, gas-liquid ratio, and nano -particle concentration were studied on gas consumption, separation factor, and recovery factor of CO2 gas in the separation process. Experiments were performed at 277.15 K and two initial pressures of 3.0 and 4.0 MPa. The presence of silica had a positive effect on gas consumption, separation, and recovery factors. The optimum results are obtained for the nanofluids including silica and potassium hydroxide, which at best case improved the gas consumption, separation factor, and recovery factor by 36 %, 29 % and 38 % compared to the pure water, respectively. The optimum nanoparticle concentration was obtained to be 0.1 wt% Besides, as the gas-liquid ratio increased, the gas consumption value raised. However, the relative amount of gas consumption and the recovery factor decreased. While the gas consumption was a direct function of the initial pressure, the separation and recovery factors were inverse functions of that.

Automated summary

In this study, the separation of CO2 gas from a CO2/CH4 mixture was investigated using the gas hydrate formation method. Silica and APTES surface-modified silica nanoparticles with potassium hydroxide were used as additives. The presence of silica improved gas consumption, separation factor, and recovery factor. The optimal nanofluids with silica and potassium hydroxide showed a significant increase in gas consumption, separation factor, and recovery factor compared to pure water. The gas-liquid ratio and initial pressure affected the gas consumption, separation, and recovery factors.