CO₂ Hydrate Slurry Flow Characteristics Using Tetrahydrofuran as a Promoterfor Carbon Capture, Transportation,and Sequestration

Carbon capture and sequestration (CCS) through hydrates offers environmental benefits, as mostly water is used during hydrate formation. Hydrate formation from gaseous CO₂ is well explored in the literature; however, studies from liquid-phase CO₂ need more attention, as liquid CO₂ offers higher hydrate formation rates and thermodynamic conditions of oceanic sequestration mostly in the liquid state. CO₂ hydrate in water is often a stochastic and slow kinetic process, especially from liquid CO₂, affecting the overall process efficiency. Tetrahydrofuran (THF) is one of the potential hydrate promoters that can aid the process favorably, forming CO₂ hydrate slurries. The formation kinetics of hydrate slurries are often characterized by their rheological behavior. In this study, we investigate the high-pressure rheology of a CO₂ hydrate slurry formed from gaseous and liquid CO₂ using various concentrations of the THF promoter at a constant temperature of 274.15 ± 0.5 K and at 3.5 MPa (gaseous CO₂) and 5 MPa (liquid CO₂). CO₂ hydrate slurries formed from pure water are observed to agglomerate at a lower shear rate. However, the antiagglomeration effect is shown by CO₂ hydrate slurries formed in the presence of THF. THF+CO₂ hydrate has shown pseudoplastic behavior, and THF inclusion reduces typical hydrate nucleation time and delays hydrate dissociation. A small amount of THF, about 1 to 2 wt %, can be effective in improving the rheology of the CO₂ hydrate slurry for efficient capture, storage, and transportation of CO₂.