Storage of pure CO2 and CH4 and separation of their binary mixture in three different classes of nanostructured adsorbentssilicalite, C168 schwarzite, and IRMOF-1have been compared at room temperature using atomistic simulation. CH4 is represented as a spherical Lennard-Jones molecule, and CO2 is represented as a rigid linear molecule with a quadrupole moment. For pure component adsorption, CO2 is preferentially adsorbed than CH4 in all the three adsorbents over the pressure range under this study, except in C168 schwarzite at high pressures. The simulated adsorption isotherms and isosteric heats match closely with available experimental data. A dual-site Langmuir−Freundlich equation is used to fit the isotherms satisfactorily. Compared to silicalite and C168 schwarzite, the gravimetric adsorption capacity of pure CH4 and CO2 separately in IRMOF-1 is substantially larger. This implies that IRMOF-1 might be a potential storage medium for CH4 and CO2. For adsorption from an equimolar binary mixture, CO2 is ...

Storage and separation of CO2 and CH4 in silicalite, C168 schwarzite, and IRMOF-1: a comparative study from Monte Carlo simulation.

Separation of olefin/paraffin is an energy-intensive and difficult separation process in petrochemical industry. Energy-efficient adsorption process is considered as a promising alternative to the ...

Adsorption of ethane, ethylene, propane, and propylene on a magnesium-based metal-organic framework.

Separation of CO2 and N2 from CH4 is significantly important in natural gas upgrading, and capture/removal of CO2, CH4 from air (N2) is essential to greenhouse gas emission control. Adsorption equilibrium and kinetics of CO2, CH4, and N2 on an ordered mesoporous carbon (OMC) sample were systematically investigated to evaluate its capability in the above two applications. The OMC was synthesized and characterized with TEM, TGA, small-angle XRD, and nitrogen adsorption/desorption measurements. Pure component adsorption isotherms of CO2, CH4, and N2 were measured at 278, 298, and 318 K and pressures up to 100 kPa, and correlated with the Langmuir model. These data were used to estimate the separation selectivities for CO2/CH4, CH4/N2, and CO2/N2 binary mixtures at different compositions and pressures according to the ideal adsorbed solution theory (IAST) model. At 278 K and 100 kPa, the predicted selectivities for equimolar CO2/CH4, CH4/N2, and CO2/N2 are 3.4, 3.7, and 12.8, respectively; and the adsorption ...

Adsorption of CO2, CH4, and N2 on Ordered mesoporous carbon: Approach for greenhouse gases capture and biogas upgrading

The separation of ethane from ethylene is of prime importance in the purification of chemical feedstocks for industrial manufacturing. However, differentiating these compounds is notoriously difficult due to their similar physicochemical properties. High-performance porous adsorbents provide a solution. Conventional adsorbents trap ethylene in preference to ethane, but this incurs multiple steps in separation processes. Alternatively, high-purity ethylene can be obtained in a single step if the adsorbent preferentially adsorbs ethane over ethylene. We herein report a metal-organic framework, MUF-15 (MUF, Massey University Framework), constructed from inexpensive precursors that sequesters ethane from ethane/ethylene mixtures. The productivity of this material is exceptional: 1 kg of MOF produces 14 L of polymer-grade ethylene gas in a single adsorption step starting from an equimolar ethane/ethylene mixture. Computational simulations illustrate the underlying mechanism of guest adsorption. The separation performance was assessed by measuring multicomponent breakthrough curves, which illustrate that the separation performance is maintained over a wide range of feed compositions and operating pressures. MUF-15 is robust, maintains its performance in the presence of acetylene, and is easily regenerated by purging with inert gas or by placing under reduced pressure.

A Robust Ethane-Trapping Metal-Organic Framework with a High Capacity for Ethylene Purification

CO2 adsorption over ion-exchanged zeolite beta with alkali and alkaline earth metal ions

Adsorption equilibria of single components for pure methane, ethane, ethylene, hydrogen, and nitrogen onto activated carbon adsorbent (Calgon Co.) were measured. The results were obtained with a static volumetric method at 293.15 K, 303.15 K, and 313.15 K and at pressures up to 2 MPa. Experimental data were correlated by the Langmuir−Freundlich equation. Isosteric enthalpies of adsorption were calculated and shown according to surface loading.

Adsorption equilibria of methane, ethane, ethylene, nitrogen, and hydrogen onto activated carbon

In order to optimize the performance of an adsorption column, the adsorption and regeneration dynamic characteristics were studied for 20% methane and 80% hydrogen binary system on nonisothermal and nonadiabatic conditions. The adsorption dynamic characteristics were studied at various flow rates, 7.2 LPM to15.8 LPM, and at various adsorption pressures, 6 to 12 atm. Also, regeneration dynamic characteristics were studied at various purge rates, 1.5 to 3.5 LPM, and constant pressure, 1.2 atm. Nonisothermal and nonadiabatic models, considering linear driving force model and Langmuir-Freundlich adsorption isotherm model, were considered to compare between prediction and experimental data.

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Byoung Uk Choi

Papers

Adsorption equilibria of methane, ethane, ethylene, nitrogen, and hydrogen onto activated carbon

Adsorption and regeneration dynamic characteristics of methane and hydrogen binary system