Single- and multicomponent adsorption fixed bed breakthrough experiments of carbon dioxide (CO2), methane (CH4), and nitrogen (N2) on commercial binder-free beads of 4A zeolite have been studied at 313, 373, and 423 K and a total pressure of up to 5 bar. The ternary experiments (CO2/CH4/N2) show a practically complete separation of CO2 from CH4/N2 at all the temperatures studied, with selectivity at 313 K of CO2 around 24 over CH4 and 50 over N2. The adsorption equilibrium data measured from the breakthrough experiments were modeled by the dual-site Langmuir isotherm, and the breakthrough results were simulated with a fixed bed adsorption model taking into account axial dispersion, mass-transfer resistances, and heat effects. The mathematical model predicts with a good accuracy the systematic behavior of the single- and multicomponent breakthrough results based on the independent parameters calculated from well-established correlations and intracrystalline diffusivities for zeolite 4A available in the literature. The results showed in the present work evidence that the binder-free beads of zeolite 4A can be employed to efficiently separate CO2 from CO2/CH4/N2 mixtures by fixed bed adsorption.

Recently, developing bio-based carbon materials due to the surface chemistry and a large spectrum of pore structures have received much attention. In the present work, a series of activated carbon (AC) adsorbents were synthesized from the compost derived by the mechanical/biological treatment of municipal solid wastes and evaluated regarding their CO 2 uptake. The AC samples were characterized by sulfuric acid and calcination by N 2 at 400 and 800°C. Then, the CO 2 uptake capacities were evaluated by dynamic breakthrough experiments in a temperature range of 40-100°C and pressures up to 3 bar. The presented data were properly described by Langmuir model and it was revealed that the CMSW-S-800 sample, treated with sulfuric acid and activated at 800°C, has the highest CO 2 uptake capacity with an amount adsorbed around 2.6 mol/kg at 40°C. In the next step, a mathematical model has been developed to match the experimental dynamic breakthrough data and design a pressure swing adsorption (PSA) cyclic process to evaluate the capacity and potential of the best AC sample for CO 2 adsorption. The results arising from this work showed a possible route for the application of the compost as a source of activated carbon for the sorption of greenhouse gases.

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The adsorption of carbon dioxide (CO 2 ), methane (CH 4 ), and nitrogen (N 2 ) has been studied on potassium-exchanged (95%) binder-free beads of Y zeolite through single, binary, and ternary fixed bed breakthrough experiments, covering the temperature range between 313 and 423 K and a pressure of up to 350 kPa. At 313 K and 350 kPa, the single-component data obtained showed that the amounts adsorbed of CO 2 , CH 4 , and N 2 are around 6.42, 1.45, and 0.671 mol kg −1 , respectively. The binary experiments CO 2 / N 2 carried out under typical post-combustion conditions show a selectivity of CO 2 over N 2 around 104. The ternary experiments resulted in the selectivities of CO 2 over CH 4 and N 2 around 19 and 45, respectively. The adsorption equilibrium data have been modeled by the dual-site Langmuir model, and the breakthrough experiments were numerically simulated with a suitable dynamic fixed bed adsorption model. The model predicts with good accuracy the systematic behavior of all breakthrough experiments. The results shown in the present work prove that the potassium-exchanged binder-free beads of Y zeolite enhance the amount adsorbed of CO 2 at low partial pressure over other alkali metal-exchanged faujasites and efficiently separate it from binary (CO 2 /N 2 ) and ternary (CO 2 /CH 4 /N 2 ) mixtures by fixed bed adsorption.