Experimental Determination of CO2 Solubility in Liquid CH4/N2 Mixtures at Cryogenic Temperatures

Coalbed methane (CBM) is an atypical natural gas that may contain a large amount of nitrogen in addition to methane. When liquefying such CH 4 /N 2 mixtures, knowledge of solid solubility is very important and, in particular, CO 2 solubility data are essential for determining the CO 2 purification index. Although experimental data for CO 2 solubility in pure methane are available for various conditions, such experimental data for CH 4 /N 2 mixtures are rare. In this paper, a solid–liquid equilibrium experimental apparatus using a static-analytic method is described. Data for CO 2 solubility in pure liquid methane were obtained and their accuracy was verified by comparison with published values. Solubility of CO 2 in CH 4 /N 2 mixtures with nitrogen molar fractions of 10, 30, 50, and 70% were then measured at cryogenic temperatures between −190 and −150 °C.