Phase behavior of methane and carbon dioxide hydrates in meso- and macro-sized porous media

In this report, the hydrate phase equilibria of binary CH4 + water and CO2 + water systems in porous silica gels with nominal diameters of 6, 30, and 100 nm are measured. The results obtained are compared with model predictions using the modified van der Waals–Platteeuw equation, whose prediction curves show good agreement with the experimental values. As noted in other literature, the inhibition effect attributed to decreased water activity in silica gel pores is enlarged as the nominal diameter of the porous media decreases. However, based on the solid-state NMR spectra, the hydrate structure formed in the silica gel pores is the same structure-I as that of bulk conditions regardless of pore sizes. The phase equilibria and modeling equation for CH4 and CO2 hydrates in silica gels are expected to provide prediction method for this system for future applications of gas hydrates with porous media.