Showing papers on "BET theory published in 1974"
TL;DR: In this article, it was shown that thermal treatment of a copper/zinc oxide CO-shift catalyst in a reducing gas causes a decrease in the BET surface area as well as partial reduction of zinc oxide followed by the formation of α-brass.
60 citations
TL;DR: In this article, the authors applied the BET theory to determine the surface area and pore structure of four gases (N2, A, Kr and CO2) on a number of clay mineral and oxide systems.
Abstract: Sorption isotherms for four gases (N2, A, Kr and CO2) , commonly used in specific surface area and pore structure measurements, have been accurately determined on a number of clay mineral and oxide systems. Specific surface areas obtained by application of the BET theory to these isotherms illustrate the extent to which the apparent cross-sectional areas for these sorbed gases vary with surface structure, ex- changeable cation and microporosity. V-n plots for nitrogen adsorption on these materials using nitrogen adsorption on crystalline materials of large crystal size as a standard isotherm provide appreciable ranges of linearity in each case. The specific surface areas obtained from these straight line plots agree well with the corresponding BET values. The linearity of these plots for illite clays indicates the absence of capillary condensation and that adsorption in slit-shaped pores takes place largely by the formation of physically adsorbed layers on the surfaces. Much larger BET specific surface areas were obtained from carbon dioxide sorption at 196K on goethite, hematite and gibbsite than from nitrogen, argon and krypton sorption at 78"K. It is suggested that enhanced sorption of CO2 into microporous regions of the oxides, inaccessible to the other gases, occurs in a similar fashion to that frequently observed for coal and charcoal materials. V-n plots for CO2 sorption in these materials using that for an illite clay as a standard isotherm, support this conclusion. Considerably lower BET specific surface areas were obtained for CO 2 sorption on kaolinite than were obtained for nitrogen, argon and krypton sorption. The shape of the V-n plots for CO., sorption on kao- linite compared with illite suggest that an initial specific adsorption of CO2 on the kaolinite is followed by a change in state with the completion of this layer, allowing normal multilayer formation to proceed.
57 citations
TL;DR: In this paper, values of the nitrogen BET specific surface areas calculated from data supplied by many laboratories on four currently available surface area standards are presented and compared, and analytical data, representative adsorption isotherms and typical BET plots are given.
Abstract: Values of the nitrogen BET specific surface areas calculated from data supplied by many laboratories on four currently available surface area standards are presented and compared. Analytical data, representative adsorption isotherms and typical BET plots are given. Various factors affecting the accuracy of nitrogen BET surface area measurements are summarised.
28 citations
TL;DR: The effect of Cu(II) added to β-FeOOH in various ratios up to 6% Cu/Fe was examined by X-ray diffraction, electron microscope, BET surface area, DTA, TGA and chemical analyses as discussed by the authors.
Abstract: The effect of Cu(II) added to β-FeOOH in various ratios up to 6% Cu/Fe was examined by X-ray diffraction, electron microscope, BET surface area, DTA, TGA and chemical analyses. Differing from other cases reported previously, Cu(II) showed no effect, but thermal changes of the Cu-doped samples indicated a reinforcement of bonding by Cu.
18 citations
TL;DR: In this article, the influence of irradiation of adjusted uranium, to a burn-up of 6400 MWd/t, has been studied upon its reactivity out-of-reactor in carbon dioxide at 375-500° C and in air at 200-300° C.
15 citations
TL;DR: Changes in hysteresis of the adsorption isotherms indicated that the increased surface area after milling was mostly external for amosite and the increase for chrysotile was primarily caused by the greater availability of micropores.
Abstract: Nitrogen and argon isotherms were determined on amosite and on chrysotile asbestos at −183° and −195°C, and in three states of subdivision. BET surface area determinations showed that milling increased the amosite surface area from 1.3 to 11.0 m2/g, and the chrysotile from 15.3 to 48.4 m2/g. Changes in hysteresis of the adsorption isotherms indicated that the increased surface area after milling was mostly external for amosite and the increase for chrysotile was primarily caused by the greater availability of micropores. Measurements of pore size showed averages of 58.5 A for amosite and 80.5 A for chrysotile. Heat of adsorption determinations, calculated from the Clausius-Clapeyron equation, showed only minor differences between the two minerals.
11 citations
Patent•
07 Nov 1974
TL;DR: In this paper, the SO2 content of combustion gases from sulphuric acid plants is removed by adjusting their relative humidity to 35-90% and passing them through a solid carbon bed having a surface area exceeding 1000 m2/g.
Abstract: Gases having relatively low SO2 content (1 vol.%) such as combustion gases or gases from sulphuric acid plants, are proetically completely freed of SO2 by adjusting their relative humidity to 35-90% and passing them through a solid carbon bed having a BET surface area exceeding 1000 m2/g a micropore vol. of 0.5-0.7 cm3/g., a macropore vol. of 0.45-0.60 cm3/g., and a hydrophobia quotient of 1.5-2.5. The contact time is pref. >8 secs. The resulting sulphuric acid has high concn. (40-60%). There is no need to regenerate the catalyst.
3 citations
TL;DR: In this article, a 2-constant BET equation with closely agreeing constants c for the standard curve and the adsorption isotherm of the adsorbent under study is derived.
1 citations