Relaxation NMR Measurements of the Transformation of Absorbed Water in the Pores of a Carbon Sorbent during the Decomposition of Methane Hydrate

The decomposition of the gas hydrate formed from absorbed water and methane inside a carbon sorbent with a rigid structure was studied by NMR relaxation methods. The moisture content in the sample corresponded to the partial filling of pores. At the stage of hydrate formation, the cell with the sample and gas was maintained under conditions of gas hydrate stability for several tens of hours. Under these conditions, the NMR T2 spectrum of water and methane released after the decomposition of the gas hydrate differs significantly from the spectrum of a wet sample with the gas taken without hydrate. Further redistribution of water and methane in the pores was studied, and it was shown that the NMR T2 spectra shift toward shorter T2 relaxation times for a long period of time after the decomposition of the gas hydrate, which reflects the transition of water and methane to more tightly bound states.