Promoting and Inhibitory Effects of Hydrophilic/Hydrophobic Modified Aluminum Oxide Nanoparticles on Carbon Dioxide Hydrate Formation

Hydrate-based CO 2 capture from large emission sources is considered a promising process for greenhouse gas mitigation. The addition of nanoparticles may promote or inhibit the formation of hydrates. In this work, CO 2 hydrate formation experiments were performed in a dual-cell high-pressure reactor. Non-modified, hydrophilic modified and hydrophobic modified aluminum oxide (Al 2 O 3 ) nanoparticles at different concentrations were added to assess their promoting or inhibitory effects on CO 2 hydrate formation. The equilibrium temperature and pressure, induction time, and total gas consumption during CO 2 hydrate formation were measured. The results show that the presence of Al 2 O 3 nanoparticles exerts little effect on the phase equilibrium of CO 2 hydrates. Under the experimental conditions, the addition of all Al 2 O 3 nanoparticles imposes an inhibitory effect on the final gas consumption except for the 0.01 wt% addition of hydrophilic modified Al 2 O 3 nanoparticles. The induction time required for the nucleation of CO 2 hydrates mainly ranges from 70 to 90 min in the presence of Al 2 O 3 nanoparticles. Compared to the absence of nanoparticles, the addition of non-modified and hydrophilic modified Al 2 O 3 nanoparticle reduces the induction time. However, the hydrophobic modified Al 2 O 3 nanoparticles extend the induction time.