CO<sub>2</sub> hydrate formation enhancement via bare and hybrid silica nanoparticles effect: Implications for hydrate-based CO<sub>2</sub> sequestration

Carbon dioxide geological storage gives tremendous promise for mitigating anthropogenic carbon emissions. CO2 hydrate has been given rising attention due to its potential in carbon geo-sequestration projects. The effect of silica nanoparticles (SiNPs) on the kinetics of CO2 hydrate formation was systematically studied at 3.5 MPa and 280 K. Pure (bare) and surface-modified (hybrid) SiNPs were separately characterized and used in this study. The effect of bare and hybrid SiNPs concentrations on the induction time of CO2 hydrate formation was investigated. A high-pressure, high-temperature stainless steel vessel was used as a hydrate reactor, and pressure-temperature data were continuously recorded to follow the hydrate formation process. Results revealed that the SiNPs significantly impact the kinetics of CO2 hydrate formation. The increase of Hybrid SiNPs concentration (>0.03 wt% hybrid SiNPs), significantly reduces the induction time and thus accelerates the rapid formation of CO2 hydrate. In contrast, bare SiNPs showed a lower effect on CO2 hydrate formation. Further, the increase of bare SiNPs (e.g., >0.07 wt% bare SiNPs) can tend to eliminate the effect of NPs on induction time. Thus, surface-modified SINPs can significantly enhance CO2 hydrate formation when formulated correctly.