Measurements and calculations of the equilibrium adsorption amounts of CO2–N2, CO–N2, and CO2–CO mixed gases on 13X zeolite

Abstract

Pressure swing adsorption (PSA) is one practical process for CO 2 separation from the exhaust gases in various industries, such as blast furnace gas in steel works. For optimum design of the PSA process, precise estimation of the adsorption equilibrium of mixed gases is desired. The ideal adsorbed solution (IAS) model is a reliable model for this estimation. However, the IAS model requires convergent calculations, which significantly increase the calculation load, especially in dynamic PSA simulations. An analytical formula such as the extended Langmuir (EX-LM) equation is more useful for calculation of the equilibrium adsorption amounts of mixed gases. A drawback of this equation, however, is the uncertainty of the thermodynamic consistency and consequently the accuracy of the calculation results. In order to clarify the necessary conditions for application of the EX-LM equation as an approximation of the IAS model with Langmuir equation (IAS-LM model), both the analytical features and the estimation accuracy of these different methods were evaluated. To evaluate the accuracy of the equations, the equilibrium adsorption amount of mixed gases consisting of CO 2 , N 2 , and CO, which are the major gas components of blast furnace gas in steel works, on 13X zeolite were measured experimentally. The results confirmed that the accuracy of the EX-LM equation varies depending on the gas pressure and also the affinities of the adsorbates. Under higher gas pressure conditions, more reliable calculation results were obtained by the IAS-LM model.

Adsorption Behavior of Crystal Violet and Congo Red Dyes on Heat-Treated Brazilian Palygorskite: Kinetic, Isothermal and Thermodynamic Studies

“…The best mathematical adjusts to the Langmuir model suggest that the adsorption of CV on Pal-700T occurs mainly via the chemisorption process, in which a monolayer of the adsorbate is deposited on the surface of the palygorskite [54,92,93]. The higher value of K L means greater interaction between the adsorbent and adsorbate [94,95]; thus, Pal-700T has a greater interaction with CV molecules, while Pal has a lower interaction, which is consistent with the results obtained experimentally. On the other hand, the result of the mathematical adjustments performed for the samples Pal, Pal-300T and Pal-500T showed that the Freundlich model was the one that best fit the experimental data of adsorption of CV and CR, as it presents R 2 values closest to 1.…”

Using Molecular Simulations to Unravel the Benefits of Characterizing Mixture Permeation in Microporous Membranes in Terms of the Spreading Pressure

“…The values of the adsorption selectivities, S ads , are plotted in Figure a as function of Φ. The highest values of S ads are realized with cation-exchanged zeolites (NaX and NaY) and MgMOF-74 with exposed Mg 2+ cation sites, resulting in strong binding of CO 2 molecules to cations. , Significantly lower S ads values are realized with all-silica zeolites. Remarkably, the hierarchy of diffusion selectivities is essentially the reverse of the hierarchy of S ads ; see MD simulation data for S diff versus Φ in Figure b.…”

Opening the Toolbox: 18 Experimental Techniques for Measurement of Mixed Gas Adsorption

“…Volumetric methods also use large adsorbent samples compared to breakthrough and gravimetric methods. A persistent difficulty of the volumetric methods is lack of control over the pressure and composition of the gas phase at equilibrium, , although the use of a manostat , or electronic dosing control can grant control over equilibrium pressure. Three important variations of this method are described in the following subsections.…”