Masoud Mofarahi

Separating CO2 by forming hydrate is anew technology for reducing the greenhouse effect. The main challenges of this method are the rate of hydrate formation, suitable conditions for hydrate formation, and separation efficiency. In the present study, phase equilibrium condition for the semi-clathrate hydrate of gas mixture (12.4% CO2+87.6% N2) and separation factor of CO2 measured at the temperature 274.15 K and pressure range from 2 to 4 MPa. The effect of tetra butyl ammonium chloride (TBAC) aqueous solution at mass fractions 0.05 on the hydrate formation condition and CO2 separation efficiency was studied in a 700 cm3 stirred reactor. Phase equilibrium data for the semi-clathrate hydrates of the gas mixture (12.4% CO2+87.6% N2) were obtained at the temperature range (278-282) K and pressure range (2-4 MPa). The results show that the formation pressure of gas mixture hydrate can be decreased obviously in TBAC aqueous solution. Obtained data compared with those of articles with a similar gas mixture. The formation pressure of hydrate in the presence of tetra butyl ammonium fluoride (TBAF) and tetra butyl ammonium bromide (TBAB) is lower than TBAC at the same temperature. The effect of tetra butyl ammonium halide on improving hydrate formation conditions is higher than other additives. The highest CO2 separation factor (11.1) was in the range of feed pressure, 3 MPa. It found that increasing the feed pressure harms CO2 separation, and optimal initial pressure is needed, isochoric method was used to obtain the phase equilibrium data of semi-clathrate hydrate. A CO2 gas analyser was used to measure the Concentration of CO2 gas in the mixture.