Air separation sorbents: Mixed-cation zeolites with minimum lithium and silver

Epiepang, Franklin E.; Yang, Xiong; Li, Jianbo; Wei, Yuwei; Liu, Yingshu; Yang, Ralph T.

doi:10.1016/j.ces.2018.12.048

Cited by 28 publications

(21 citation statements)

References 34 publications

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“…The normal behavior is that the surface area of zeolites increases when sodium ions are exchanged by lithium ions, 42 which occurred in six of the samples. This is because the ionic radius of Li + is smaller than the ionic radius of Na + , and the degree of dispersion of zeolite particles increases after the ion exchange process, creating empty spaces between them.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and ion exchange of zeolites produced from kaolin for separation of oxygen from atmospheric air

Feltrin

Souza

Aquino³

et al. 2021

Int J Applied Ceramic Tech

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Lithium‐based zeolites are the most commonly used materials in PSA (pressure swing adsorption) oxygen concentration from atmospheric air. Synthesizing these adsorbents using mineral raw materials adapts to worldwide environmental requests, as only high‐purity chemical reactants such as aluminates and silicates are usually used. The present work aims to synthesize and characterize zeolites using kaolin as raw material by studying the influence of the metakaolinization temperature and SiO2/Al2O3 and H2O/Na2O molar ratios by experimental design. Ion exchange was used to incorporate lithium into synthesized zeolites. Kaolin was treated thermically and characterized, and zeolites were synthesized by a hydrothermal reaction. After synthesis, ionic exchange of Na+ ions by Li+ was performed. The results indicated the presence of three main phases, zeolites A, X, and P. Using ANOVA, it was found that the factors that contributed significantly to the formation of zeolite X were the H2O/Na2O and SiO2/Al2O3 molar ratios. For zeolite A, the major influence was by the metakaolinization temperature and for zeolite P none of the factors was influential. Zeolites that incorporated higher amounts of lithium showed higher N2 adsorption potential, indicating that even without pure phases formed, it was possible to obtain similar adsorption efficiency to commercial zeolite.

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Section: Resultsmentioning

confidence: 99%

Synthesis and ion exchange of zeolites produced from kaolin for separation of oxygen from atmospheric air

Feltrin

Souza

Aquino³

et al. 2021

Int J Applied Ceramic Tech

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“…Zeolites find widespread use as adsorbents in a range of commercially-important gas separations involving small molecules, including air separation (where N 2 /O 2 selectivity is required) and hydrogen purification (CO 2 /H 2 ). [1][2][3] Furthermore, advanced materials and chemical engineering research continues to drive improved performance in these and similar applications, [4] and also in CO 2 adsorption in natural gas and biogas upgrading (CO 2 /CH 4 ) [5,6] and carbon capture from power plant and industrial emissions (CO 2 /N 2 and CO 2 /CO,H 2 ). [7,8] The performance of zeolites in gas separation relates directly to their high chemical and thermal stability and also to their structural features: high internal surface area accessible via well-defined pores and the presence of extra-framework cations.…”

Section: Introductionmentioning

confidence: 99%

“…These cations affect their adsorption properties in a number of ways. First, the direct cation‐adsorbate interaction enables molecules to be differentiated based on their dipole moment or polarizability – cationic zeolites can separate N 2 from O 2 due to its higher polarizability, for example [1,2] . Extra‐framework cations can also control the effective pore size, if they are located close to windows, as shown by the increasing pore size of K‐, Na‐ and Ca‐forms of zeolite Linde A (known as 3A, 4A, and 5A respectively).…”

Section: Introductionmentioning

confidence: 99%

“…Zeolites find widespread use as adsorbents in a range of commercially‐important gas separations involving small molecules, including air separation (where N 2 /O 2 selectivity is required) and hydrogen purification (CO 2 /H 2 ). [ 1 , 2 , 3 ] Furthermore, advanced materials and chemical engineering research continues to drive improved performance in these and similar applications, [4] and also in CO 2 adsorption in natural gas and biogas upgrading (CO 2 /CH 4 )[ 5 , 6 ] and carbon capture from power plant and industrial emissions (CO 2 /N 2 and CO 2 /CO,H 2 ). [ 7 , 8 ]…”

Section: Introductionmentioning

confidence: 99%

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Cation Ordering and Exsolution in Copper‐Containing Forms of the Flexible Zeolite Rho (Cu,M‐Rho; M=H, Na) and Their Consequences for CO₂ Adsorption

Łozińska

Jamieson

Verbraeken

et al. 2021

Chemistry A European J

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The flexibility of the zeolite Rho framework offers great potential for tunable molecular sieving. The fully copper-exchanged form of Rho and mixed Cu,H-and Cu,Naforms have been prepared. EPR spectroscopy reveals that Cu 2 + ions are present in the dehydrated forms and Rietveld refinement shows these prefer S6R sites, away from the d8r windows that control diffusion. Fully exchanged Cu-Rho remains in an open form upon dehydration, the d8r windows remain nearly circular and the occupancy of window sites is low, so that it adsorbs CO 2 rapidly at room temperature. Breakthrough tests with 10 % CO 2 /40 % CH 4 mixtures show that Cu 4.9 -Rho is able to produce pure methane, albeit with a relatively low capacity at this p CO2 due to the weak interaction of CO 2 with Cu cations. This is in strong contrast to Na-Rho, where cations in narrow elliptical window sites enable CO 2 to be adsorbed with high selectivity and uptake but too slowly to enable the production of pure methane in similar breakthrough experiments. A series of Cu,Na-Rho materials was prepared to improve uptake and selectivity compared to Cu-Rho, and kinetics compared to Na-Rho. Remarkably, Cu,Na-Rho with > 2 Cu cations per unit cell exhibited exsolution, due to the preference of Na cations for narrow S8R sites in distorted Rho and of Cu cations for S6R sites in the centric, open form of Rho. The exsolved Cu,Na-Rho showed improved performance in CO 2 /CH 4 breakthrough tests, producing pure CH 4 with improved uptake and CO 2 /CH 4 selectivity compared to that of Cu 4.9 -Rho.

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“…Zeolites are widely used in industry for the separation of various gas mixtures, in particular for air separation by the PSA method [1][2][3][4][5]. Modifying the surface of high-silicon zeolites of Y and ZSM types by introducing metal nanoparticles (NPs) is one of the promising directions for creating nanocomposite materials with specified properties for gas purification and separation due to the unique properties of NPs.…”

Section: Introductionmentioning

confidence: 99%

Modification of Zeolites Y and ZSM-5 adsorption of nanoparticles of transition metals from back-micellar solutions for separation of gas mixtures

et al. 2021

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On the basis of granular synthetic zeolites NaY, HY, and ZSM-5, adsorbents containing nanoparticles of silver, cobalt, molybdenum, and tungsten were obtained. The samples have a lower surface polarity in comparison with the initial zeolites, which is reflected in the selectivity of a number of samples with respect to argon. This is due to the fact that the argon molecule interacts with zeolites only through nonspecific forces. Modification was performed by interacting with reverse-micellar solutions of nanoparticles. The actual sizes of metal particles and their distribution over the surface of the modified samples of zeolites have been determined by the method of transmission electron microscopy. The samples’ equilibrium adsorption capacities for oxygen and argon (25°С and atmospheric pressure) and the separation coefficient of the argon–oxygen mixture as the ratio of Henry’s coefficients have been determined. It has been demonstrated that samples of the NaY zeolite modified with silver nanoparticles have the separation coefficient value of the argon–oxygen gas mixture equal to 1.6.

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Air separation sorbents: Mixed-cation zeolites with minimum lithium and silver

Cited by 28 publications

References 34 publications

Synthesis and ion exchange of zeolites produced from kaolin for separation of oxygen from atmospheric air

Synthesis and ion exchange of zeolites produced from kaolin for separation of oxygen from atmospheric air

Cation Ordering and Exsolution in Copper‐Containing Forms of the Flexible Zeolite Rho (Cu,M‐Rho; M=H, Na) and Their Consequences for CO₂ Adsorption

Modification of Zeolites Y and ZSM-5 adsorption of nanoparticles of transition metals from back-micellar solutions for separation of gas mixtures

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Air separation sorbents: Mixed-cation zeolites with minimum lithium and silver

Cited by 28 publications

References 34 publications

Synthesis and ion exchange of zeolites produced from kaolin for separation of oxygen from atmospheric air

Synthesis and ion exchange of zeolites produced from kaolin for separation of oxygen from atmospheric air

Cation Ordering and Exsolution in Copper‐Containing Forms of the Flexible Zeolite Rho (Cu,M‐Rho; M=H, Na) and Their Consequences for CO2 Adsorption

Modification of Zeolites Y and ZSM-5 adsorption of nanoparticles of transition metals from back-micellar solutions for separation of gas mixtures

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Cation Ordering and Exsolution in Copper‐Containing Forms of the Flexible Zeolite Rho (Cu,M‐Rho; M=H, Na) and Their Consequences for CO₂ Adsorption