Computing bubble-points of CO2/CH4 gas mixtures in ionic liquids from Monte Carlo simulations

Abstract

Computing bubble-points of multicomponent mixtures using Monte Carlo simulations is a non-trivial task. A new method is used to compute gas compositions from a known temperature, bubble-point pressure, and liquid composition. Monte Carlo simulations are used to calculate the bubblepoints of carbon dioxide (CO 2) and methane (CH 4) mixtures in the ionic liquids (ILs) 1-n-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [bmim][Tf 2 N] and 1-ethyl-3-methylimidazolium diethylphosphate [emim][dep]. The Continuous Fractional Component Monte Carlo (CFCMC) method in the osmotic ensemble has been used to compute the solubility of CO 2 /CH 4 gas mixtures at different temperatures (T), pressures (P), and gas compositions (y i). The effect of T , P , and y i on the real CO 2 /CH 4 selectivity (i.e., the selectivity of CO 2 in the presence of CH 4) is investigated. The real selectivity will differ from the ideal selectivity, which is defined as the ratio of the Henry's constants, if the solubility of CO 2 is influenced by the presence of CH 4. The computed real selectivities are compared with the experimentally obtained real and ideal selectivities. The real CO 2 /CH 4 selectivity decreases with increasing temperature and pressure, while the gas phase composition

Solubility of sulfur compounds in commercial physical solvents and an ionic liquid from Monte Carlo simulations

“…Monte Carlo simulations are performed in the osmotic ensemble where the number of solvent molecules, temperature, and pressure of the simulation box are kept constant [7,12,13,[16][17][18][19][20][21][22][23]. The vapor pressure of the investigated solvents at their operating temperature is negligible which makes it possible to consider them as non-volatile liquids in simulations.…”

“…In these cases, computational methods, e.g., Monte Carlo simulations, play an important role in providing the required VLE data. This study is a supplement to our previous experimental and simulation work, focused mainly on CO 2 /CH 4 solubilities and selectivities [6,[8][9][10][11][12][13]. Here, we focus on the solubility and the selectivity of sulfur compounds.…”

“…In recent years, ionic liquids (ILs) have been extensively investigated for natural gas or syngas sweetening purposes [6,7] as well as for carbon capture [6,[8][9][10][11][12][13]. Most of the ILs have a very low vapor pressure, high chemical and thermal stability, low flammability, and relatively high acid gas capacities [6].…”

Gibbs ensemble Monte Carlo simulations of multicomponent natural gas mixtures

“…The second mixture contains N 2 , CH 4 , CO 2 , H 2 S, C 2 H 6 , and C 3 H 8 , C 5 H 12 , C 7 H 16 and C 10 H 22 and corresponds to the experimental system (mixture 14) studied by Yarborough [17]. Although Gibbs ensemble simulations are often performed for unary, binary and ternary (confined) systems, its application to multicomponent (i.e., 4 or more components) systems is relatively rare [18][19][20][21][22][23][24][25]. The reason for this is twofold; (1) experimental (pTxy) data for multicomponent systems are extremely scarce, which complicates validation of simulation results and (2) as it will become apparent in the next section, performing a multicomponent Gibbs ensemble simulation requires an increased effort compared to unary and binary systems.…”

Computing equation of state parameters of gases from Monte Carlo simulations

“…have been devised to perform phase equilibrium calculations using MC simulations [7,8]. The grand-canonical (µV T ) ensemble is mostly used to compute adsorption properties, while the Gibbs or osmotic ensemble is prefered for absorption studies [9][10][11][12][13][14][15][16][17][18][19][20]. In ensembles with a fixed chemical potential or fugacity (e.g., µV T and osmotic ensemble), the gas phase is often described by an equation of state, while the properties of the adsorbed/absorbed phase are computed from the simulations [21,22].…”