Physical adsorption of gases at high pressure. IV. An improvement of the Dubinin—Astakhov adsorption equation

Affinity coefficients of the Polanyi/Dubinin adsorption isotherm equations: A review with compilations and correlations

Knudsen diffusion in microporous carbon membranes with molecular sieving character

Diffusivities in the micropore and adsorption equilibrium constants were determined for neon, argon, krypton, xenon, nitrogen, methane, ethylene, ethane, propylene, propane, n-butane, and benzene on molecular sieving carbon by chromatographic measurement and moment analysis. Isosteric heat of adsorption was found to be 2.6 times heat of vaporization for the gases examined here. Two separate linear relations were obtained between activation energies of diffusion in micropore and isosteric heats of adsorption for rare gases, methane, and benzene, and for n-paraffin and n-olefin except methane.

Adsorption rate on molecular sieving carbon by chromatography

Crystalline microporous oxides such as zeolites are indispensable materials in various applications ranging from industrial processes to everyday life, such as catalysts, ion-exchange materials, and molecular sieves. Most of them contain tetrahedrally coordinated metal atoms, but octahedrally coordinated metal centers have recently attracted much attention as building blocks of crystalline microporous metal oxides. Manganese oxides (pyrolusite, hollandite, todorokite, and romanechite) with micropores are the only crystalline porous materials based solely on octahedra (octahedral molecular sieves). These manganese oxides contain microtunnel pores consisting of {MnO6} octahedra that share edges and corners. Here we describe a novel type of octahedral molecular sieve, namely, crystalline orthorhombic Mo3VOx (x = 11.2), in which the microchannel is constructed by seven-membered rings of corner-sharing MO6 (M = Mo or V) octahedra. It is isostructural to orthorhombic MoVNbTeO compounds, which are very active and selective oxidation catalysts for light alkanes. These mixed metal oxides have a layered orthorhombic structure with a slab composed of sixand seven-membered rings of corner-sharing {MO6} octahedra and pentagonal {(M)M5O27} units with a {MO7} pentagonal bipyramid and five edge-sharing {MO6} octahedra, whereM is Mo, V, or Nb. The layered sixand seven-membered rings form channel structures. The Te atom is believed to be located both in the sixand seven-membered rings and block the channel. Recently, we succeeded in preparing an orthorhombic Mo3VOx compound that contains only Mo and V, [6] in which the channel is expected not to be blocked (Figure 1).

Molybdenum–Vanadium‐Based Molecular Sieves with Microchannels of Seven‐Membered Rings of Corner‐Sharing Metal Oxide Octahedra

Adsorption equilibria of various gases and vapors on molecular-sieving carbon were measured. The data were correlated by the Dubinin-Astakhov equation: W=W0 exp [-(A/E0)n], and the characteristic values of adsorption were determined. The equation covers the adsorption of various kinds of gases and vapors. The exponent n in the equation is about 3 for organic gases and lies between 2 and 3 for inorganic gases. The charactersitic energy of adsorption is expressed as E=β(ΔH0)s, where (ΔH0)s is the standard heat of vaporization of a standard material such as benzene and the coefficient β is approximately equal to the ratio of the parachor of the adsorbate to that of the standard material. Studies are made of three different types of deviations from the Dubinin-Astakhov equation, observed in the course of experiment.

Correlation of adsorption equilibrium data of various gases and vapors on molecular-sieving carbon

Adsorption Equilibrium on Molecular-sieving Carbon

IN THE PROCESS FOR REMOVING SULFUR OXIDES FROM WASTE GASES WITH EMPLOYMENT OF ACTIVATED CARBON AS THE ADSORBENT, THE CHEMICAL EXHAUSTION OF ACTIVATED CARBON AND THE LOWERING OF ITS ABILITY FOR ADSORBING SULFUR OXIDES IN THE REGENERATION STEP CAN BE REMARKABLY PRVENTED BY REGENERATING THE SULFUR OXIDES-ADSORBING ACTIVATED CARBON WITH THE DESORBENT CONTAINING CARBON MONOXIDE GAS AND/ OR HYDROGEN GAS IN A CONCENTRATION AT LEAST ABOUT 40% AT A TEMPERATURE FROM ABOUT 230*C. TO ABOUT 450*C. THE MOST ADVANTAGEOUS RESULTS CAN BE ATTAINED BY EMPLOYING VANADIUM OXIDE-SUPPORTING ACTIVATED CARBON AS THE ADSORBENT.

Yoshitomo Eguchi

Papers

Correlation of adsorption equilibrium data of various gases and vapors on molecular-sieving carbon

Adsorption Equilibrium on Molecular-sieving Carbon

Process for removing sulfur oxides from waste gas