Methane Hydrate Uptake of MCM-41 Mesoporous Molecular Sieves with Preadsorbed Water

Ordered meosoporous molecular sieves of MCM-41 were prepared by adjusting the pH with acetic acid. The synthesized samples were evaluated by 77 K nitrogen-adsorption data. The sample synthesized by a onetime pH adjustment has the same good characters as that synthesized by a three-times pH adjustment. The morphology and crystal structure of the calcined MCM-41 materials were examined with XRD and TEM, in which the ordered channel structure was confirmed. The sorption equilibrium isotherms of wet samples showed a sharp rise, because the large amount methane hydrate had been formed in the MCM-41 samples' porous space. The methane sorption amount of the mesoporous MCM-41 sample with preadsorbed water reached 10.87 mmol at R-W, = 2.0, which was 2.97 times that of the dry mesoporous MCM-41 sample. The comparative methane sorption capacities of the three ordered mesoporous materials (MCM-41, SBA-15, and large-pore MCM-41) by preadsorbtion of the same water mass (R-W, = 2.0) are almost identical, and no previous articles have reported similar results for the mesoporous materials. However, the methane hydrate formation pressures of the three samples are different due to the pore diameter effect.