Adsorption Equilibrium Of CH4 Research Articles

Simulation of CO2/CH4 high pressure separation on microporous activated carbon

Pure component adsorption equilibrium of CH4 and CO2 on activated carbon have been studied at three different temperatures, 298, 323, and 348 K within a pressure range of 10–2000 kPa. Binary adsorption equilibrium isotherm was described using extended Sips equation and ideal adsorbed solution theory (IAST) model. Experimental breakthrough curves of CO2/CH4 (40:60 in a molar basis) were performed at four different pressures (300, 600, 1200, and 1800 kPa). The experimental results of binary isotherms and breakthrough curves have been compared to the predicted simulation data in order to evaluate the best isotherm model for this scenario. The IAST and Sips models described significantly different results for each adsorbed component when higher pressures are set. These different results cause a significant discrepancy in the estimation of the equilibrium selectivity. Simulated and experimental equilibrium selectivity data provided by IAST presented values of around 4, for CO2/CH4, and extended Sips presented values of around 2. Also, simulated breakthrough curves showed that IAST fits better to the experimental data at higher pressures. According to the simulations, in a binary mixture at total pressure over 800 kPa, extended Sips model underestimated significantly the CO2 adsorbed amount and overestimated the CH4 adsorbed amount.

Cryogenic Adsorption of Methane and Carbon Dioxide on Zeolites 4A and 13X

The utilization of adsorption processes operating at low temperatures can be interesting in the context of production of liquefied natural gas (LNG), where they can constitute a lower energy alternative as hybrid technologies with cryogenic distillation. This paper provides the necessary parameters to design an adsorption process for selective removal of CO2 from methane at low temperatures to satisfy LNG specifications, with particular emphasis on a temperature swing adsorption (TSA) process. Adsorption equilibrium of CH4 and CO2 on commercial zeolite 4A and zeolite 13X is reported at cryogenic temperatures: 198, 208, 223, 248, and 279 K. Carbon dioxide is much more adsorbed than methane, and CO2 isotherms are extremely steep at low temperatures. In the studied low-temperature range, it was observed that zeolite 4A has a very different behavior toward CH4 and CO2; adsorption of methane is entirely controlled by diffusion (kinetic control), while adsorption of CO2 is mostly controlled by the shape of the isotherm (equilibrium control). Adsorption breakthrough curves of a mixture of 1.5% CO2 and 98.5% CH4 were measured in the zeolite 4A adsorbent at 204 K to identify transport phenomena at such low temperatures and verify if adsorption equilibrium can be described on the basis of pure component data. Experiments were performed at different total pressures (1 and 10 bar) and different flow rates.

A Comparative Study of CO2and CH4Adsorption on Silicalite-1 Fabricated by Sonication and Conventional Method

Silicalite-1 is pure polymorph silica that is considered a member of zeolite family due to the similarity of its framework to the well-known ZSM-5. It is an organophilic and hydrophobic material with molecular sieving property that allows it to be widely used as an adsorbent. In this work, silicalite-1 is synthesized by conventional hydrothermal treatments at atmospheric (T = 80 °C) and high pressures (T = 150 °C), respectively. In addition, the procedure is repeated using ultrasound waves during the mixing and ageing steps to shorten the synthesis time. The high crystallinity and phase purity of high-temperature autoclaved and sonicated samples are confirmed by X-ray powder diffraction and scanning electron microscopy results. Moreover, adsorption equilibrium of CH4 and CO2 has been studied experimentally to investigate the influence of textural properties of the obtained products on their adsorption performance. The experiments were performed in a batch system on the basis of a volumetric measurement te...

Correlation and Calculation of Multicomponent Adsorption Equilibria Data Using a Generalized Adsorption Isotherm

Enhanced by the need for reliable and accurate data of multicomponent gas adsorption equilibria on porous solids like activated carbons or zeolites, a new method to measure and correlate coadsorption equilibria has been developed. This method is a combination of gravimetric or volumetric measurements of the total load of pure or multicomponent adsorbates (Staudt, 1994; Gregg and Sing, 1982) and a correlation and calculation procedure using a new adsorption isotherm (AI) (Keller, 1990). This AI is thermodynamically consistent and describes adsorbates with fractal dimension for single- or multicomponent systems and load dependent adsorption energies. This method allows calculation of partial loads of multicomponent coadsorption equilibria from pure component data and the total loads of the mixture adsorption equilibria. This will be demonstrated for binary and ternary adsorption equilibria of CH4, C2H4 and C2H6 on activated carbon (Reich et al., 1980).