Showing papers on "BET theory published in 1969"

The Internal Surface and Pore Structure of Enamel

Abstract: Krypton adsorption studies demonstrated an easily accessible system of pores in enamel, measuring between 10 and 300 A, volume 0.26%, with a surface area of about 0.4 sq m/gm (BET analysis). These figures are much lower than is suggested by figures for water content, possibly resulting from non-penetration of the organic matrix by krypton. Some measurements on demineralized enamel were also made.

Novel anthraquinone hydrogenation catalyst

Abstract: A novel hydrogenation catalyst, especially useful for the catalytic hydrogenation of an anthraquinone working compound in the process for producing hydrogen peroxide, is described containing at least 0.05 percent by weight of metallic palladium dispersed on alumina supporting spheres, wherein the major crystalline structure of the alumina spheres is in the form of delta-alumina, theta-alumina, or mixtures of delta- and theta-aluminas and is substantially free of alpha-alumina, gamma-alumina or alpha-alumina monohydrate, wherein the alumina spheres have substantially no pores larger than about 0.06 micron, a BET surface area of over 20 m.2/gm., and wherein the palladium metal penetration into the pores of the supporting alumina surface is no more than about 40 or 50 microns.

Production of hydrogen peroxide by anthraquinone process

Abstract: An improvement in the catalytic hydrogenation of an anthraquinone working compound is obtained during the production of hydrogen peroxide by employing a hydrogenation catalyst containing 0.05 to 5 percent of palladium dispersed over the surface of alumina supporting spheres, said spheres having substantially no pores larger than about 0.06 microns in diameter, having a BET surface area of between 20 and 200 m.2/g., and having the palladium metal penetrating the pores of the support surface no greater than about 50 microns.

The determination of the surface area of sepiolite from carbon dioxide adsorption isotherms

Abstract: Summary Sepiolite has a microporous structure the pores of which may be penetrated to differing extents by molecules of different gases. A study has been made of the adsorption of CO2 on outgassed sepiolite (from Amboseli, Tanzania) at 193°, 209·7°, 273·2°, and 298·2 °K using a gravimetric method. Values of the surface area of sepiolite were calculated from BET (Brunauer, Emmett, and Teller) and Kaganer plots of results, assuming molecular areas for CO2 based on extrapolated liquid densities. There were only relatively small deviations from a mean value of 279 m2/g. However, the values were much lower than those previously determined by adsorption of N2 and of other gases. It is suggested that CO2 adsorbed at these temperatures should be assumed to be in the liquid state, but that the usual method of calculating the molecular areas of adsorbed CO2 from the liquid densities at these temperatures yields values which are too low. Molecular areas of 20·8 A2 at 193 °K and 23·4 A2 at 209·7 °K are preferred. Isosteric heats of adsorption at different coverages were calculated from the isotherms. The results indicated heterogeneity of the surface, with decreases in the values of the heat of adsorption occurring at low coverages and in the‘monolayer region’. They compare well with values calculated from the BET equation.

Sorption-desorption hysteresis in fibrous silica gel (Santocel C) with isomeric monohydric aliphatic alcohols

Abstract: By employing the quartz fibre spring technique, sorption-desorption hysteresis at 35° has been studied of Iso-propyl, Iso-Butyl, Sec-Butyl, Tert-Butyl, Active Amyl and Iso-Amyl alcohols on fibrous silica gel (Santocel C) activated at 250°. The isotherms of all the alcohols have clearly defined “knees”. By the application of BET theory, the monolayer capacities are determined. Knowing the specific surface area of fibrous silica gel, assuming oriented sorption of the isomeric alcohols with the OH group attached to surface; the cross-sections of the alcohol molecules are calculated. Excepting Iso-Propyl and Sec-Butyl alcohols, all others have cross-sections greater than that of normal aliphatic alcohols. These higher values are to be expected in view of the side CH3 groups. The exceptional behaviour of Iso-Propyl and Sec-Butyl alcohols is not clear.