1-Propanol as a co-guest of gas hydrates and its potential role in gas storage and CO2 sequestration

Abstract

Abstract The inclusion of 1-propanol (1-PrOH) as a co-guest of gas hydrates in the presence of CH 4 and CO 2 and its potential role in gas storage and CO 2 sequestration were investigated focusing primarily on macroscopic hydrate phase equilibrium behavior and microscopic structural and cage filling characteristics. The powder X-ray diffraction (PXRD) patterns confirmed that both double CH 4 + 1-PrOH and double CO 2 + 1-PrOH hydrates are cubic structure II (sII) hydrates. 1-PrOH did not act as a remarkable thermodynamic hydrate promoter or inhibitor for CH 4 hydrate systems, though it did act as a significant thermodynamic hydrate inhibitor for CO 2 hydrate systems despite its participation as a co-guest in the hydrate lattices. The 13 C NMR results revealed that 1-PrOH was found in the large 5 12 6 4 cages of the sII hydrate along with CH 4 at lower 1-PrOH concentrations, and the chemical formulas for the double CH 4 + 1-PrOH hydrates were found to be 2.13 CH 4 · 0.53 1-PrOH · 17 H 2 O for the 1-PrOH 1.0 mol% solution and 1.85 CH 4 · 0.75 1-PrOH · 17 H 2 O for the 1-PrOH 5.6 mol% solution. The overall experimental results provide a better understanding of guest–host interaction, guest distributions, and structural transition in guest gas + 1-PrOH hydrates for the potential application of 1-PrOH in gas storage and CO 2 sequestration.