Methane Monte Carlo simulation

A7 Ethane/methane selectivity calculated from grand canonical Monte Carlo simulations of mixtures in slit IS at a temperature of 296 K. The selectivity is defined as the ratio of the mole fractions in the pore to the ratio of mole fractions in the bulk. H is the slit width defined in terms of the methane collision diameter (Tch,- (Figure awn from Crackncll R F, D Nicholson and N Quirke 1994. A Grand Canonical Monte Carlo Study ofLennard-s Mixtures in Slit Pores 2 Mixtures of Two-Centre Ethane with Methane. Molecular Simulation 13 161-175.)... 

Fig. 2.2. Average electrostatic potential mc at the position of the methane-like Lennard-Jones particle Me as a function of its charge q. mc contains corrections for the finite system size. Results are shown from Monte Carlo simulations using Ewald summation with N = 256 (plus) and N = 128 (cross) as well as GRF calculations with N = 256 water molecules (square). Statistical errors are smaller than the size of the symbols. Also included are linear tits to the data with q < 0 and q > 0 (solid lines). The fit to the tanh-weighted model of two Gaussian distributions is shown with a dashed line. Reproduced with permission of the American Chemical Society...

Kowalczyk P, Tanaka H, Kaneko K, Terzyk AP, and Do DD. Grand canonical Monte Carlo simulation study of methane adsorption at an open graphite surface and in slit like carbon pores at 273 K. Langmuir, 2005 21(12) 5639-5646. 

Ravishanker G, Mezei M, Beveridge DL (1982) Monte Carlo simulation study of the hydro-phobic effect. Potential of mean force for aqueous methane dimer at 25 and 50 °C. Farad Symp Chem Soc 17 79-91... 

An important step in understanding the local structure around a nonpolar solute in water was made by Jorgensen et al. Using Monte Carlo simulations based on an intermolecular potential, which contained Lennard-Jones and Coulomb contributions, they determined the number of water molecules in the first hydration layer (located between the first maximum and the first minimum of the radial distribution function) around a nonpolar solute in water. This number (20.3 for methane, 23 for ethane, etc.) was surprisingly large compared with the coordination numbers in cold water and ice (4.4 and 4, respectively). These results provided evidence that major changes occur in the water structure around a nonpolar solute and that the perturbed structure is similar to that of the water—methane clathrates, ... 

Fig. 5-44. Composite cell map in which the Monte Carlo simulations have been applied to methane, ethane and propane anomalies in the Overthrust Belt, Wyoming-Utah, highlighting the regions where all three of these gases are above their respective medians.

Figure 5 Multiscale approach to understand rate of CO2 diffusion into and CH4 diffusion out of a structure I hydrate, (left) Molecular simulation for individual hopping rates, (middle) Mesoscale kinetic Monte Carlo simulation of hopping on the hydrate lattice to determine dependence of diffusion constants on vacancy, CO2 and CH4 concentrations, (right) Macroscopic coupled non-linear diffusion equations to describe rate of CO2 infusion and methane displacement. Graph from Stockie. ...

Ravishanker etal. (1982) extended the Monte Carlo simulation between two methane molecules in water-like particles. The results obtained by Ravishanker et al are quite different from those by Pangali et al., as well as those obtained by theoretical calculations by Pratt and Chandler (1977). The most striking difference is the occurrence of a second minimum at about 6 A, which corresponds to a configuration of a water-bridge between the two solutes rather than the water-separated configuration obtained by Pangali etal. (1979a,b) (Fig. 4.44). In my... 

Finn and Monson [139] first tested the predictability of IAS theory for binary systems using the isothermal isobaric Monte Carlo simulation on a single surface. However, this system does not represent real adsorption systems. Tan and Gubbins [140,141] conducted detailed studies on the binary equilibria of the methane-ethane system in slit-shaped micropores using the nonlocal density function theory (NLDFT). The selectivity of ethane to methane was studied in terms of pore width, temperature, pressure, and molar fractions. 

Skipper NT, Sposito G, Chang FC (1995b) Monte Carlo simulation of interlayer molecular stmcture in swelling clay minerals 2. Monolayer hydrates. Clays Clay Miner 43 294-303 Smit B (1995) Simnlating the adsorption isotherms of methane, ethane, and propane in the zeohte silicalite. 

Figures 1, 2 and 3 shows the results for 750 K with Mean Field, Dynamic Monte Carlo simulations without and with lateral interactions for methane activation and for carbon hydrogenation on Ru(OOOl) surface. We start first to compare the methane activation process. MFA and DMC without lateral interactions show exactly the same results, at this...

Shah M, Tsapatsis M, Siepmann JI, Ilja J (2015) Monte carlo simulations probing the adsorptive separation of hydrogen sulfide/methane mixtures using all-silica zeolites. Langmuir. Ahead of Print... 

H. Schindler, R. Vogelsang, V. Staemmler, M.A. Siddiqi, P. Svejda, A initio intermolecular potentials of methane, nitrogen methane + nitrogen and their use in Monte Carlo simulations of fiuids and fluid mixtures. Mol. Phys. 80(6), 1413 (1993)... 

Grand canonical Monte Carlo simulations performed for natural gas adsorbed on carbon have demonstrated that the optimum pore size is 0.76 nm, as mentioned earlier (methane adsorption (capillary condensation) does not takes place at room temperature) thus, a further increase of the slit width would lower the particle density without a significant increase in amounts adsorbed. These calculations predict that the theoretical maximum methane storage capacity of carbon at 3.5 MPa is 209 VA for a monolithic carbon that fills the vessel and contains a minimum amount of macropore volume and no external... 

FIGURE 7.20. Potential of average force between two methane molecules in water, obtained by Monte Carlo simulation. Redrawn with changes from Ref (1). 

We describe proeedures, based on the slit pore model and Monte Carlo simulation, for predicting the adsorption of pure gases in active carbons given only a single carbon dioxide probe adsorption isotherm. Predictions are made at ambient temperature up to quite high pressure for methane, ethene, ethane, propene and propane. The key development in our work concerns our method for calibrating gas - surface interactions, i.e. we calibrate these interactions to a reference active carbon rather than a low surface area carbon as in most other work of this type. Our predictions highlight limitations in our surface model and experiments. 

Microcalorimetry measurements are combined with Grand Canonical Monte Carlo simulations in order to understand more deeply the interactions between methane and two types of faujasite systems. The modelling study, based on newly derived force fields for describing the adsorbate/adsorbate and adsoibate/adsorbent interactions, provide isotherms and evolutions of the differential enthalpy of adsorption as a fimction of coverage for DAY and NaX which are in very good accordance with those obtained experimentally. The influence of the location of the extra-framework cations within the supercages on these thermodynamics properties is also pointed out. Furthermore, the microscopic mechanisms of CH4 adsorption is then carefully analysed in each faujasite system which are consistent with the trend observed for the differential enthalpies of adsorption. 

The isosteric heats of adsorption of methane in BPL activated carbon and ethane in MCM-41 were obtained by Monte Carlo simulation. The simulated absolute isosteric heats were converted into their experimental excess counterparts using a thermodynamie equation, which was derived by the thermodynamic analysis of the Clausius-Clqieyron equation for the isosteric heats. The difference between absolute and excess adsorption is small at low pressure in small pores but becomes bigger as the pressure increases, and is substantial in pores with a pore size bigger than 20 A even at low pressures. Excellent fits were obtained between experimental and simulated isosteric heats of adsorption of methane in BPL activated carbon and ethane in an MCM-41 sample. A pore size distribution model was used to relate simulation results for pores of different sizes to the experimental adsorbent. It is found that the isosteric heat is a more sensitive measure of the structure of activated carbon adsorbents than an adsorption isotherm. 

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