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

Degradation of desiccants in temperature swing adsorption processes: The temperature dependent degradation of zeolites 4A, 13X and silica gels

Experimental studies on 3A and 4A zeolite molecular sieves regeneration in TSA process: Aliphatic alcohols dewatering–water desorption

Equilibrium and Kinetic Behaviour of CO2 Adsorption onto Zeolites, Carbon Molecular Sieve and Activated Carbons

The efficacy of carbon molecular sieve and solid amine for CO2 separation from a simulated wet flue gas by an internally heated/cooled temperature swing adsorption process

In the current study, the effect of modified zeolite using (3-aminopropyl) triethoxysilane in polybutylene succinate (PBS) and polylactic acid (PLA) blend was investigated. Two types of modified zeolite i.e., zeolite 5A and 13X at 3wt% of polymer blend between PBS and PLA were mixed together in twin-screw extruder and thin-films were produced by cast-film extruder. The thickness of each film is between 50 – 70 micron. Mechanical properties, thermal properties, morphological properties and permeability of oxygen, carbon dioxide as well as water vapour were investigated. Adding of zeolite 5A into PBS/PLA blend was found to increase more tensile strength and Young’s moduluswith the comparison to zeolite 13X whereas the zeolite 13X and 5A had increased the percentage of elongation at break more than PBS/PLA blend. The zeolite 5A and 13X tended to increase the thermal stability of the composite films. Gas permeation results showed that PBS/PLA with zeolite 5A allowed the permeation of carbon dioxide and oxygen more than 13X in composite films. Moreover, water vapour transmissionrate of PBS/PLA with zeolite 5A was higher than the one with zeolite 13X.

Systematic evaluation of materials for post-combustion CO2 capture in a Temperature Swing Adsorption process

Adsorption of methane, ethane and ethylene on molecular sieve zeolites

Atmospheric water harvesting on MIL-100(Fe) upon a cyclic adsorption process

Modeling of regeneration stage of 3A and 4A zeolite molecular sieves in TSA process used for dewatering of aliphatic alcohols

The performance of zeolites 5A and 13X is numerically investigated in oxygen separation from air by a two-bed PSA system. The effect of operating variables such as adsorption step time, P H /P L ratio and cycle time was investigated on product purity and recovery. The simulation results showed that nitrogen adsorption capacity on zeolite 13X was slightly more than the one on zeolite 5A. In the completely same operating conditions, zeolite 5A had a larger mass transfer zone than zeolite 13X. Therefore, the adsorption and desorption rate of nitrogen on zeolite 5A is less than zeolite 13X. Moreover, for the equal volume of adsorbed nitrogen on both adsorbents, zeolite 5A is more capable rather than zeolite 13X to desorb much more volume of nitrogen at certain time. Furthermore, for achieving oxygen with purity of 96%, utilizing zeolite 5A is more economical than zeolite 13X, when 5.5<P H /P L <7 and 75<cycle time≤90.

In a way to overcome challenges with global warming, the use of fossil fuels in producing environmentally friendly energy towards reducing the ozone layer depletion and greenhouse gas emissions by participating countries is of interest. The adsorption refrigeration system has the advantages of a long lifespan and its environmental friendliness; however, its major disadvantage is the low coefficient of performance, which is a function of adsorbent–adsorbate, with zeolite–water as the most common adsorbent–adsorbate working pair. Zeolites 4A and 13X are the most used zeolite classes due to their higher selectivity for separating mixtures of CO2/N2 and CO2/CH4/N2 and their high-water adsorption capability, respectively. In this study, for the first time, the synthesis of zeolites 4A and 13X from natural sources (Kankara kaolin) and the mixture optimization for solar adsorption refrigeration application were considered. Raw Kankara kaolin, beneficiated Kankara kaolin, calcined Kankara kaolin and synthesized zeolites 4A and 13X were characterized using X-ray fluorescence, while the synthesized zeolites 4A and 13X were characterized using X-ray diffraction. Using the mixture simplex lattice design of experiment, mixtures of zeolites 4A and 13X were developed and characterized using Brunauer, Emmett and Teller analysis to obtain their pore size, specific surface area and pore volume. The statistical analysis produced the mathematical models of the response that were significant for pore size and specific surface area. The analysis proposed an optimal solution of 75 wt% zeolite 4A and 25 wt% zeolite 13X, which gave a desirability of 0.944.

The purpose of this dataset is to provide a comparison between synthesized and commercial 4A and 13X type zeolites. Metakaolin produced from the calcination of beneficiated kaolin at 750 °C for 4 h was dealuminated using sulphuric acid to get the required silica to alumina ratio for the zeolite synthesis. Zeolite 4A and 13X samples were characterized along-side with the commercial variants using X-ray fluorescence (XRF), X-ray diffraction (XRD), Brunauer, Emmett and Teller (BET) and scanning electron microscopy (SEM) techniques. These analyses revealed that, the zeolites synthesized are of comparatively acceptable quality. The pore size of 120.859 nm, pore volume of 0.0065 cm3/g and surface area of 22 m2/g were obtained from BET analyses for zeolite 4A synthesized from kaolin, while the commercial zeolite 4A used as control gave pore size of 58.143 nm, pore volume of 0.2462 cm3/g and surface area of 559.13 m2/g. In the same vein, the pore size of 10.5059 nm, pore volume of 0.135847 cm3/g and surface area of 324.584 m2/g were obtained from BET analyses for zeolite 13X synthesized from kaolin, while the commercial zeolite 13X gave pore size of 7.2752 nm, pore volume of 0.135951 cm3/g and surface area of 310.0906 m2/g.

Understanding the adsorption mechanism is essential for developing efficient technologies to capture carbon dioxide from industrial flue gases. In this work, laboratory measurements, density functional theory calculations, and molecular dynamics simulations were employed to study CO2 adsorption and diffusion behavior in LTA-type zeolites. The CO2 adsorption isotherms measured in zeolite 5A are best described by the Toth model. Thermodynamic analysis indicates that the adsorption process is spontaneous and exothermic, with an enthalpy change of -44.04 kJ/mol, an entropy change of -115.23 J/(mol·K), and Gibbs free energy values ranging from -9.68 to -1.03 kJ/mol over the temperature range of 298-373 K. The isosteric heat of CO2 adsorption decreases from 40.35 to 21.75 kJ/mol with increasing coverage, reflecting heterogeneous interactions at Ca2+ and Na+ sites. The adsorption kinetics follow a pseudo-first-order model, with an activation energy of 2.24 kJ/mol, confirming a physisorption mechanism. The intraparticle diffusion model indicates that internal diffusion is the rate-limiting step, supported by a significant reduction in the diffusion rate. The DFT calculations demonstrated that CO2 exhibited a -35 kJ/mol more negative adsorption energy in zeolite 5A than in zeolite ITQ-29, attributable to strong interactions with Ca2+/Na+ cations in 5A that were absent in the pure silica ITQ-29 framework. The molecular dynamics simulations based on molecular force fields indicate that CO2 diffuses more rapidly in ITQ-29, with a diffusion coefficient measuring 2.54 × 10-9 m2/s at 298 K, whereas it was 1.02 × 10-9 m2/s in zeolite 5A under identical conditions. The activation energy for molecular diffusion reaches 5.54 kJ/mol in zeolite 5A, exceeding the 4.12 kJ/mol value in ITQ-29 by 33%, which accounts for the slower diffusion kinetics in zeolite 5A. There is good agreement between experimental measurements and molecular simulation results for zeolite 5A across the studied temperature and pressure ranges. This confirms the accuracy and reliability of the selected simulation parameters and allows for the study of zeolite ITQ under similar simulation conditions. This research provides insights into CO2 adsorption energetics and diffusion within LTA-type zeolite frameworks, supporting the rational design of high-performance adsorbents for industrial gas separation.

The present study aimed to investigate the adsorption behavior of heavy metal ions (Cu 2+ , Cd 2+ , and Pb 2+ ) on zeolite 4A (26.9 m 2 /g) and zeolite 13X (550.1 m 2 /g) at neutral pH in batch experiments. Influencing parameters on the adsorption were studied, including equilibrium time, solution pH, and adsorbent dose. The metal removal efficiencies at neutral pH were considerably higher than those at acidic pH. Cu 2+ and Cd 2+ were more efficiently adsorbed on zeolite 4A, while the greater removal of Pb 2+ was achieved with zeolite 13X. With an initial concentration of 300 ppm and an adsorbent‐to‐liquid ratio of 0.2% w/v, the highest removal efficiencies were 91.1% for Cu 2+ and 95.2% for Cd 2+ with zeolite 4A, and 92.9% for Pb 2+ with zeolite 13X. The experimental data fitted well with the Langmuir isotherm and the pseudo‐second‐order models, indicating the monolayer formations and the dominance of chemisorption. Zeolite 4A showed higher pseudo‐second‐order rate constants than zeolite 13X. The intraparticle diffusion contributed more significantly to the adsorption of Cu 2+ and Cd 2+ than that of Pb 2+ on the zeolites. The findings from this study provide valuable insights into the adsorption behavior of heavy metals on different kinds of zeolites in neutral solution.

Adsorptive removal of ultra-low concentration H2S and THT in CH4 with and without CO2 on zeolite 5A and 13X pellets