Adsorption Equilibrium on Molecular-sieving Carbon

Kawazoe, Kunitaro; Astakhov, V. A.; Kawai, Takazumi; Eguchi, Yoshitomo

doi:10.1252/kakoronbunshu1953.35.1006

Cited by 24 publications

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“…(3) from βE0, 6 where ΔHv is the enthalpy of vaporization at the boiling point, and equals to 12.6 kJ/mol. Analyses of the signal intensity (peak area) data given in Fig.…”

Section: Dr Analysis Of Nmr Adsorption Isotherms Observed For the Sigmentioning

confidence: 99%

Analysis of the Temperature and Pressure Dependence of the 129Xe NMR Chemical Shift and Signal Intensity for the Derivation of Basic Parameters of Adsorption as Applied to Zeolite ZSM-5

et al. 2007

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Nano-materials, such as zeolites with nano-sized pores, are attractive new materials in industry, and are expected to offer a promising future efficient way to settle problems in environmental ecology as well. 1 It is important when developing such new materials for different purposes to evaluate physicochemical properties, such as the surface area, cage/pore structure, adsorption coefficient and surface distribution of metal ions. Surface area, for example, has usually been determined by a classical volumetric or gravimetric method, such as B.E.T. adsorption analysis using nitrogen as an adsorbent gas, and advanced techniques, such as an electronic microscope, SEM or TEM also, solid state NMR have recently been used to analyze the physicochemical properties of a surface in detail.129 Xe NMR has long been applied to analyze a porous structure in zeolites, 2 and quite recently the most interesting topic, hyperpolarized 129 Xe NMR, have emerged, in which the sensitivity can be enhanced by several orders by utilizing the optical pumping technique.3 It is highly expected that such a sensitivity enhanced 129 Xe NMR will be widely used to characterize nano-materials that have been newly synthesized, or of wide applicability in industry and medicine. In these 129 Xe NMR studies, basic parameters, such as the surface area and the adsorption energy are also hoped to be determined by using Xe as an adsorbent. 129 Xe NMR can be used for this purpose without any facilities of the traditional methodology, since it can provide a measure of the amount of adsorbed Xe through the intensity of the 129 Xe adsorbed signal. Therefore, in order to examine the applicability of 129 Xe NMR in obtaining basic adsorption parameters of the surface area and the adsorption energy for nano-materials, the temperature and pressure dependences are investigated for the chemical shift as well as the signal intensity, i.e., peak area, in the 129 Xe NMR of the present study. Experimental Reagents and chemicalsThe sample used was ZSM-5 (JRC-Z5-70Na from Mobil Catalysts Corp., Japan, Si/Al ratio = 92.5), supplied as a standard sample from Japan Catalysis Association. ZSM-5 is one of the micro-porous zeolites with an MFI structure, which is expected to contribute to improving the environment as an exchange agent for the separation of alcohol, NO removal etc. There is no super cage existing in ZSM-5, although X-or Ytype zeolite has them as the FAU structure. The pore size is 0.56 × 0.53 nm in linear structure and 0.55 × 0.51 nm in zigzag pore structure. Two structures are crossed with each other and form a 3D structure. Standard Xe gas that contains a natural abundance of 26.24%129 Xe was purchased from Japan Air Gases Ltd., and used after drying by passing over K-Na alloy, or passing through Minifine Purer supplied from Liquid Gas Co. Apparatus and procedureThe zeolite sample and Xe gas were treated in a fully shielded system made by glass-blowing. The sample was weighed into a Temperature and pressure dependences of the 129 Xe NMR chemical shift ...

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“…(3) from βE0, 6 where ΔHv is the enthalpy of vaporization at the boiling point, and equals to 12.6 kJ/mol. Analyses of the signal intensity (peak area) data given in Fig.…”

Section: Dr Analysis Of Nmr Adsorption Isotherms Observed For the Sigmentioning

confidence: 99%

Analysis of the Temperature and Pressure Dependence of the 129Xe NMR Chemical Shift and Signal Intensity for the Derivation of Basic Parameters of Adsorption as Applied to Zeolite ZSM-5

et al. 2007

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“…(12), since the adsorbed phase is considered similar to the liquid phase and then I TAS^w/wJKlq^l (ll)…”

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confidence: 99%

“…So the above equation is considered to be valid for p/po^Pc/Po> which satisfies the condition assumed for deriving Eq. (12).…”

mentioning

confidence: 99%

Method for the calculation of effective pore size distribution in molecular sieve carbon.

Horváth

Kawazoe

1983

J. Chem. Eng. Japan / JCEJ

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1,856

936

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“…In D-R analysis, the isosteric heat of adsorption, qst, can be calculated from βE0 according to Eq. ( 7), 18 where ΔHv is the enthalpy of vaporization at the boiling point, and equals to 12.6 kJ/mol:…”

Section: Calculations Of the Signal Intensity Data Based On The D-r Modelmentioning

confidence: 99%

Analysis of NMR Adsorption Isotherms of Zeolite ZSM-5: Adsorption Profiles Derived from the Pressure and Temperature Dependences of 129Xe NMR Chemical Shift and Signal Intensity

et al. 2021

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Xe NMR spectroscopy of nanomaterials, such as zeolites, can provide valuable information on the nanostructure and physicochemical properties of adsorption. In the present study the pressure and temperature dependences of the 129 Xe NMR chemical shift and the signal intensity were investigated in detail with a zeolite ZSM-5. The pressure dependence of the signal intensity at constant temperature was analyzed based on the Langmuir and Dubinin-Radushkevich (D-R) models, from which the thermodynamic parameters and energetic profiles of adsorption were obtained together with information concerning the nanospace size. From this isotherm analysis the coverage, θ, was calculated and used for isotherm analysis of the chemical shift. The θ dependence of the chemical shift was successfully fitted by an exponential function, and the results were discussed in relation to the chemical shift at zero coverage, that at full coverage and the curvature of the exponential function. The chemical shift data reported with the zeolites NaA and KA, where separated signals were observed for the different number of encapsulated Xe atoms in the α cage, were analyzed and discussed collectively.

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Adsorption Equilibrium on Molecular-sieving Carbon

Cited by 24 publications

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Analysis of the Temperature and Pressure Dependence of the 129Xe NMR Chemical Shift and Signal Intensity for the Derivation of Basic Parameters of Adsorption as Applied to Zeolite ZSM-5

Analysis of the Temperature and Pressure Dependence of the 129Xe NMR Chemical Shift and Signal Intensity for the Derivation of Basic Parameters of Adsorption as Applied to Zeolite ZSM-5

Method for the calculation of effective pore size distribution in molecular sieve carbon.

Analysis of NMR Adsorption Isotherms of Zeolite ZSM-5: Adsorption Profiles Derived from the Pressure and Temperature Dependences of 129Xe NMR Chemical Shift and Signal Intensity

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