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This work presents the effect of NaCl and NaClO4on the kinetics of methane enclathration with cyclopentane (CP) and sodium dodecyl sulfate (SDS) in a nonstirred batch reactor. Methane and 1 cm3of CP were charged sequentially to 150 cm3of solutions in a high-pressure vessel and the reaction system was cooled down to 274.6 K with an initial pressure of 7.1 MPa. Hydrates are visually observed within 1 h after the onset of cooling at a SDS concentration range of 0−200 ppm. At the end of a growth period of 2.5 h, the pressure reduces to 6.4 MPa for SDS concentrations below 20 ppm, whereas it decreases to 3.2 MPa for SDS concentrations above 50 ppm without any salts, which is very close to the hydrate equilibrium pressure. With 20 ppm SDS and 1 cm3of CP, the average enclathration rate maximizes at 1.0 mM NaCl or 5.0 mM NaClO4as the salt concentration increases from 0 to 100 mM. However, with 100 ppm SDS, it decreases monotonically with the increased salt concentration. These results not only provide an implication of reducing the SDS dosage (down to 50 ppm or less) in regard to fast enclathration but also further our understanding of the promoting role of surfactants. [ABSTRACT FROM AUTHOR]

Trapping CO2in hydrates is one of the new technologies for CO2capture and storage. One of the primary obstacles to this option is the low formation rate. This work presents the rapid formation of CO2hydrates with a small amount of cyclopentane (CP). The formation kinetics was investigated in a 474 cm3nonstirred batch reactor with 100 and 200 cm3of water. At volume ratios of CP to water between 0.01 and 0.1, the maximum growth rate is 0.32 mol h−1at CO2pressures ranging from 1.9 to 3.4 MPa and at 274 K. CO2hydrates (sI) and CO2+ CP (sII) binary hydrates coexist at the end of hydrate growth. The mole ratio of CO2entrapped in the sI hydrates to that in the sII binary hydrates is higher with 100 cm3of water than with 200 cm3of water. The same trend is also observed for the total amount of CO2entrapped in the hydrate phase. The growth rate depends not only on the water volume but also on the pressure. The hydrate growth rate and the water conversion reach a maximum at 3.06 MPa and then decrease as the pressure increases from 1.9 to 3.4 MPa with 100 cm3of water and 5 cm3of CP. The water conversion to the hydrates reaches 52% within 2 h. This accelerated formation kinetics can provide a stepping-stone for developing a new hydrate-based CO2capture and storage technique. [ABSTRACT FROM AUTHOR]