Showing papers on "BET theory published in 1986"
TL;DR: In this article, the authors measured the surface areas of different carbonaceous materials at various levels of conversion and found that the conversion rates per unit BET surface area remained mostly constant over the range of higher conversion (X > 0.4).
77 citations
TL;DR: In this paper, the surface area, surface acidity, adsorption capacity and pore sizes, TGA, X-ray powder diffraction, and activity for isopropanol decomposition were investigated.
58 citations
TL;DR: In this paper, the vanadium ion from other starting vanadium salts was considerably incorporated and atomically dispersed in the crystal, and the crystallinity, morphology, BET surface area, and acidic property of vanadosilicates changed with the kind of starting vanagent.
43 citations
01 Jul 1986
TL;DR: In this paper, the thermal decomposition of synthetic acicular goethite has been studied with special reference to the effect of atmosphere on the particle characteristics of decomposition, such as pore structure and surface area.
Abstract: The thermal decomposition of synthetic acicular goethite has been studied with special reference to the effect of atmosphere on the particle characteristics of decomposed goethite such as pore structure and surface area. The decomposition was promoted by O2 but retarded by N2 and H2O. The conversion temperature from protohematite to hematite was lowest for H2O followed by N2 and O2. The sequence of pore structure development is described and the effects of atmosphere and SiO2 coating have been explained in terms of surface mobility, which was greatly enhanced by H2O and suppressed by SiO2 coating. The variation of BET surface area with both temperature and atmosphere has been correlated with pore structure change.
30 citations
TL;DR: In this paper, the effect of calcination temperature, under isobaric thermal conditions, on the structural stability and catalytic activity for thiophene conversion of Mo-impregnated NaY and NH4NaY zeolite catalysts was made.
30 citations
TL;DR: In this paper, the data of adsorption isotherms of nitrogen adorption at 77 K on various samples of zeolites were measured. Besides derivation of specific surface area by BET analysis, samples were characterised by characterisation of samples by different attributes.
Abstract: Data of adsorption isotherms of nitrogen adsorption at 77 K on various samples of zeolites were measured. Besides derivation of specific surface area by BET analysis, samples were characterised by ...
21 citations
TL;DR: In this paper, a new, highly porous silicon-based membrane was developed by pyrolyzing a silicon-rubber material (polydimethyl siloxane) in two steps.
Abstract: A new, highly porous silicon-based membrane was developed by pyrolyzing a silicon-rubber material (polydimethyl siloxane)in two steps. The first step was performed under an inert-gas environment below 800°C. The second step was performed in air below 950°C to oxidize and cross-link Si-O chains. The resulting silicon-based material was highly porous and had a fine pore structure (maximum porosity of 50%, BET surface area of I40m2/g) suitable for hot industrial gas separation even in a highly oxidizing environment. Gas permeability studies were performed at several different temperatures using a material derived by the pyrolysis of commercial silicon-rubber tubes. The results indicated that the flow through the membrane could be adequately explained by the Knudsen diffusion mechanism. The average permeabilities were 10 to 50 times those of porous Vycor glass.
17 citations
Patent•
25 Jul 1986
TL;DR: In this article, a silver catalyst for the direct oxidation of ethylene with oxygen to give ethylene oxide is applied on a porous carrier and essentially consists of α-alumina and contains certain amounts of soluble calcium, aluminum, potassium and sodium salts.
Abstract: A silver catalyst for the direct oxidation of ethylene with oxygen to give ethylene oxide is applied on a porous carrier and essentially consists of α-alumina and contains certain amounts of soluble calcium, aluminum, potassium and sodium salts. The carrier has a BET surface area of from 0.2 to 0.8 m2 /g, a pore volume of not less than 0.5 ml/g, the pores being equally accessible to cold and warm water, and a bulk density of less than 650 kg/m3, and has a shape which, in the reactor, provides a geometric surface area of not less than 600 m2 /m3, on which more than 13% by weight of silver are applied as the active component, more than 110 kg of silver being available per m3 of reactor.
13 citations
TL;DR: An aquametric microtechnique is proposed for measuring the pre-adsorbed (residual) moisture (DeltaW) and equilibrium moisture content (H) in macroporous weakly basic anion-exchangers and their gel analogues, during the derivation of water-vapour sorption isotherms by use of a modified McBain balance in a vacuum system.
4 citations
Patent•
19 Mar 1986TL;DR: An ammonia synthesis catalyst precursor having a high surface area and containing oxides of iron, cobalt, aluminum, and an alkali metal of atomic number equal to, or greater than, 19 is described in this paper.
Abstract: An ammonia synthesis catalyst precursor having a high BET surface area and containing oxides of iron, cobalt, aluminum, and an alkali metal of atomic number equal to, or greater than, 19. On reduction the precursor gives a catalyst having a high initial activity relative to that of a catalyst obtained by reduction of a standard fused, cobalt-free, precursor. The precursor may be made by precipitation followed by calcination.
3 citations
01 Jan 1986
TL;DR: In this paper, a gas phase synthesis from silane and methane in an argon thermal rf-plasma was used to synthesize ultrafine SiC powders and the near-surface composition and structure of the particles were examined by x-ray photoelectron spectroscopy and transmission electron microscopy (TEM).
Abstract: Ultrafine SiC powders have been prepared by gas phase synthesis from silane and methane in an argon thermal rf-plasma. Bulk properties of the powders were determined by elemental analysis, x-ray diffractin, helium pycnometry, and BET surface area measurements. The near-surface composition and structure of the particles were examined by x-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). In addition to free silicon and carbon particles in the powders, free carbon and various silicon/carbon/oxygen species were found on the surface of the SiC particles.
TL;DR: In this paper, the influence of baking temperatures of carbon blocks in the oxidation with carbon dioxide, the gasification rates and exidation profiles inside of the carbon rods were investigated, and the results of the surface area for each of the thin layers was determined by the gas adsorption method applied to the cut off powder.
TL;DR: The suitability of the Huttig-type equation for the component adsorption isotherms from the mixed gases of O2 and N2 on anatase at 77K was investigated in this paper.
Abstract: The Huttig-type adsorption equation on mixed gas adsorption was derived assuming that the molecules in the 1st layer were localized, and the molecules in the 2nd or higher layers behaved as gases with molecules in a different potential from that of gas molecules. The surface areas were separately obtained by the application of this adsorption equation to the experimental total adsorption isotherms or component adsorption isotherms. The suitability of this equation for the component adsorption isotherms from the mixed gases of O2 and N2 on anatase at 77K was investigated in comparison with that of the extended BET adsorption equation for mixed gas adsorption of the experimental isotherms.The suitability showed good agreement in the range of 0.05 and 0.5 in relative pressure. This adaptable range had a wider range than that of the extended BET adsorption equation. The surface areas obtained separately by the adaptation of the equation to the experimental total adsorption isotherms and component adsorption isotherms showed reasonable agreement with those obtained from the adaptation of the Huttig-type adsorption equation of the single component adsorption for the experimental single component adsorption isotherms. From these results, even in the adsorbed phase of the mixed gas adsorption, the model of the Huttig-type adsorption equation for mixed gas adsorption was perceived to be much more reasonable than that of the localized model of the extended BET equation for mixed gas adsorption in the relative pressure range of 0.05 and 0.5.
Patent•
28 May 1986
TL;DR: In this article, a hydrocarbon conversion catalyst consisting of silica and a stabilized Y zeolite having a chemical SiO2/Al2O3 molar ratio of from 4.5/1 to 6/1, the essential x-ray powder diffraction pattern of Y, a BET surface area of at least 350 m /g and an adsorptive capacity for water vapour at 25 DEG C and a water vapor pressure of 320 Pa (2.4 Torr) of from 6 to 12 wt.
Abstract: of EP0122063A hydrocarbon conversion catalyst comprises silica and a stabilized Y zeolite having a chemical SiO2/Al2O3 molar ratio of from 4.5/1 to 6/1, the essential x-ray powder diffraction pattern of zeolite Y, a BET surface area of at least 350 m /g and an adsorptive capacity for water vapour at 25 DEG C and a water vapour pressure of 320 Pa (2.4 Torr) of from 6 to 12 wt.%. The catalyst is useful for hydrocarbon conversion, especially fluid catalytic cracking.