An Investigation of Hydrophilic Mesoporous Materials SBA-15 and Al-SBA-15 on the Behavior of Confined Carbon Dioxide Gas Hydrate Crystallization

Mesoporous materials have gained interest as nonchemical kinetic promoters of rapid gas hydrate formation, which can enable a hydrate-based gas capture and storage technology. However, questions remain regarding the influence of material hydrophilicity on carbon dioxide hydrate formation. SBA-15 and aluminum doped Al-SBA-15 silica frameworks were utilized to explore the influence of hydrophilicity on the crystallization of CO2 gas hydrate. High-pressure differential scanning calorimetry (HP-DSC) shows that the addition of aluminum into the structure of SBA-15 decreased the conversion of CO2 hydrate within the porous structure at low to moderate saturation. To further explore the influence of hydrophilicity on CO2 hydrate conversion in nanopores, tetrahydrofuran (THF), a thermodynamic promoter, was introduced to the SBA-15 framework. The introduction of THF greatly decreased the heat released by gas hydrates in the pores of SBA-15, indicating lower CO2 hydrate conversion. HP-DSC results suggest that THF does not partake in CO2 hydrate formation within the pores SBA-15 at low and moderate saturations. The findings suggest that, though hydrophilic properties enable the formation of hydrates within the nanopores, increasing material hydrophilicity will eventually hinder CO2 hydrate formation under confinement.