K+ ion distribution in zeolite ZK-4’s with various Si/Al ratios and the contribution of K+ ions to K cluster formation

Ikeda, Takuji; Kodaira, Tetsuya; Oh, Tae-Sik; Nisawa, Atsushi

doi:10.1016/s1387-1811(02)00595-4

Cited by 25 publications

(41 citation statements)

References 26 publications

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“…The expected occupancy is consistent with a crystallographic study. 38 For zeolite NaK-ZK-4 with Si/Al = 2.3 and 2.8, similar trends of the adsorption of CO 2 and N 2 were observed as for the sample with Si/Al = 1.8. The amount of N 2 adsorbed first decreased with an increased at.…”

Section: Results and Discussionsupporting

confidence: 69%

Selective Adsorption of CO₂ on Zeolites NaK-ZK-4 with Si/Al of 1.8–2.8

et al. 2020

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Zeolites with appropriately narrow pore apertures can kinetically enhance the selective adsorption of CO 2 over N 2 . Here, we showed that the exchangeable cations (e.g., Na + or K + ) on zeolite ZK-4 play an important role in the CO 2 selectivity. Zeolites NaK ZK-4 with Si/Al = 1.8–2.8 had very high CO 2 selectivity when an intermediate number of the exchangeable cations were K + (the rest being Na + ). Zeolites NaK ZK-4 with Si/Al = 1.8 had high CO 2 uptake capacity and very high CO 2 -over-N 2 selectivity (1190). Zeolite NaK ZK-4 with Si/Al = 2.3 and 2.8 also had enhanced CO 2 selectivity with an intermediate number of K + cations. The high CO 2 selectivity was related to the K + cation in the 8-rings of the α-cage, together with Na + cations in the 6-ring, obstructing the diffusion of N 2 throughout the zeolite. The positions of the K + cation in the 8-ring moved slightly (max 0.2 Å) toward the center of the α-cage upon the adsorption of CO 2 , as revealed by in situ X-ray diffraction. The CO 2 -over-N 2 selectivity was somewhat reduced when the number of K + cations approached 100%. This was possibly due to the shift in the K + cation positions in the 8-ring when the number of Na + was going toward 0%, allowing N 2 diffusion through the 8-ring. According to in situ infrared spectroscopy, the amount of chemisorbed CO 2 was reduced on zeolite ZK-4s with increasing Si/Al ratio. In the context of potential applications, a kinetically enhanced selection of CO 2 could be relevant for applications in carbon capture and bio- and natural gas upgrading.

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Section: Results and Discussionsupporting

confidence: 69%

Selective Adsorption of CO₂ on Zeolites NaK-ZK-4 with Si/Al of 1.8–2.8

et al. 2020

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“…Most of faculties of medicine around the world use the body cadaver for teaching anatomy for medical student and for research, and this type of preservation is called (anatomical preservation) [3].…”

Section: Meaning Of Preservationmentioning

confidence: 99%

A Brief Review on the Principles of Human Cadaver Preservation and Monitoring of Microbial Degradation

Alsharif¹,

Musthafa²,

Elamin³

et al. 2017

FMAR

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Putrefaction and decay of preserved cadaver and body parts is one of the major issues that the faculties of medicines in various third world countries are facing. In this study we focus on the meaning of body preservation, causes of putrefaction and we highlight our personal experiences at the Faculty of Medicine in Prince Sattam bin Abdulaziz University in KSA, in preserving the body cadavers. We studied different physical and chemical methods of preservation of cadavers and body parts at the faculty and their efficiency in preventing bacteria and fungi that cause putrefaction and decay.

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“…Ikeda et al 43 showed the occurrences of split 6-ring sites in Zeolite KA, protruding on opposite sides of the 6-ring plane either into the α-cage or into the β-cage. According to the XRD, at levels of Na + -to-K + exchange above 33% all 4-ring and 8-ring ions should be exchanged to K + .…”

Section: Journal Of Chemical Theory and Computationmentioning

confidence: 99%

Temporal Coarse Graining of CO₂ and N₂ Diffusion in Zeolite NaKA: From the Quantum Scale to the Macroscopic

Mace

Leetmaa

Laaksonen

2015

J. Chem. Theory Comput.

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The kinetic CO2-over-N2 sieving capabilities in narrow pore zeolites are dependent on the free-energy barriers of diffusion between the zeolite pores, which can be fine-tuned by altering the framework composition. An ab initio level of theory is necessary to accurately compute the energy barriers, whereas it is desirable to predict the macroscopic scale diffusion for industrial applications. Using ab initio molecular dynamics on the picosecond time scale, the free-energy barriers of diffusion can be predicted for different local pore properties in order to identify those that are rate-determining for the pore-to-pore diffusion. Specifically, we investigate the effects of the Na(+)-to-K(+) exchange at the different cation sites and the CO2 loading in Zeolite NaKA. These computed energy barriers are then used as input for the Kinetic Monte Carlo method, coarse graining the dynamic simulation steps to the pore-to-pore diffusion. With this approach, we simulate how the identified rate-determining properties as well as the application of skin-layer surface defects affect the diffusion driven uptake in a realistic Zeolite NaKA powder particle model on a macroscopic time scale. Lastly, we suggest a model by combining these effects, which provides an excellent agreement with the experimental CO2 and N2 uptake behaviors presented by Liu et al. (Chem. Commun. 2010, 46, 4502-4504).

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K+ ion distribution in zeolite ZK-4’s with various Si/Al ratios and the contribution of K+ ions to K cluster formation

Cited by 25 publications

References 26 publications

Selective Adsorption of CO₂ on Zeolites NaK-ZK-4 with Si/Al of 1.8–2.8

Selective Adsorption of CO₂ on Zeolites NaK-ZK-4 with Si/Al of 1.8–2.8

A Brief Review on the Principles of Human Cadaver Preservation and Monitoring of Microbial Degradation

Temporal Coarse Graining of CO₂ and N₂ Diffusion in Zeolite NaKA: From the Quantum Scale to the Macroscopic

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K+ ion distribution in zeolite ZK-4’s with various Si/Al ratios and the contribution of K+ ions to K cluster formation

Cited by 25 publications

References 26 publications

Selective Adsorption of CO2 on Zeolites NaK-ZK-4 with Si/Al of 1.8–2.8

Selective Adsorption of CO2 on Zeolites NaK-ZK-4 with Si/Al of 1.8–2.8

A Brief Review on the Principles of Human Cadaver Preservation and Monitoring of Microbial Degradation

Temporal Coarse Graining of CO2 and N2 Diffusion in Zeolite NaKA: From the Quantum Scale to the Macroscopic

Contact Info

Product

Resources

About

Selective Adsorption of CO₂ on Zeolites NaK-ZK-4 with Si/Al of 1.8–2.8

Selective Adsorption of CO₂ on Zeolites NaK-ZK-4 with Si/Al of 1.8–2.8

Temporal Coarse Graining of CO₂ and N₂ Diffusion in Zeolite NaKA: From the Quantum Scale to the Macroscopic