Showing papers on "BET theory published in 1989"

The first high specific surface area, pillared, layered phosphate with a narrow pore size distribution

Abstract: [Al13O4(OH)24(OH2)12]7+ has been intercalated under mild conditions into α-tin phosphate monohydrate to give α-Sn{[Al13O4(OH)24(OH)2)12]0.14H(PO4)2·nH2O}(‘Al13SnP’); calcination of ‘Al13SnP’ at 400 °C gives rise to an aluminium oxide-pillared material with a BET surface area of 228 m2 g–1 and a very narrow pore-size distribution centred at a radius of 22 A.

Absorbing precipitated silica and composition based thereon

Abstract: The invention relates to an absorbent precipitated silica and to compositions based on a liquid, for example of vitamin type, which is absorbed on this silica. The silica of the invention has the following characteristics: - BET surface area of at least 170 m /g; - oil uptake of between 220 and 300 ml/100 g; - tamped packing density of at least 0.29; - median particle diameter of between 80 and 150 m; - particle size dispersion index of not more than 0.70.

Applications of fractal geometry for characterizing hydrotreating catalysts

Abstract: The characterization of heterogeneous catalysts or porous solids involves a description of a reacting interface. The physical and chemical properties of catalysts - surface area, active site density and reactivity - have recently been quantified by fractal geometry. The use of fractal dimension rather than N 2 BET surface area provides for the determination of effective surface area for any adsorbate. The concept may be useful in predicting the reactivity of individual components in hydroprocessing. Similarly, the effects of particle size on surface area and reactivity, or the distribution of active sites on a catalyst, may be quantified by fractal geometry. Applications are discussed with specific examples.

Adsorption of CsOH on controlled porous glasses

Abstract: Adsorption of CsOH has been studied for 18 samples of porous glasses prepared from different raw glass materials by means of different thermal and chemical treatment. For all the samples studied and for 3 samples of chromatographic silica gels the adsorption capacity in relation to CsOH is proportional to the BET surface area and equals 4 μmol of cesium per 1 m2 of BET surface.

Production of zsm-5 fine particles

Abstract: PURPOSE: To improve the reproducibility of fine particles by crystallizing a material mixture incorporating silica source, alumina source, alkali metal source and water in the presence of specified seed slurry in hydrothermal synthetic conditions. CONSTITUTION: The source mixture of pH10-12 obtained by mixing silica source, alumina source, alkali metal source, pH controller and water by the molar ratios of SiO 2 /Al 2 O 3 =25-40, Na 2 O/SiO 2 =0.2-0.3, SO 4 2- /SiO 2 =0.1-0.2, into which the seed slurry is added by 10-40wt.%. The seed slurry used is such a hydrothermal synthesis slurry that incorporates a solid component showing X-ray diffraction pattern of ZSM-5 after drying and is partly crystallized to have the nitrogen adsorption BET surface area of 100-250m 2 /g. Then the source material is stirred with stirring force of 0.1-10kw/m 2 to effect crystallization under hydrothermal synthetic conditions at 100-200°C. Thus, ZSM-5 fine particles containing ≥50wt.% of primary particles with ≤1μm particle size can be obtained. COPYRIGHT: (C)1991,JPO&Japio

Flame-resistant silicone elastomers

Abstract: Compositions for obtaining compact or cellular silicone elastomers capable of being vulcanised at room temperature or at a temperature below 150 DEG C, flame-resistant, characterised in that they contain ceric oxide of BET surface area greater than or equal to 40 m /g, preferably greater than 85 m /g. Elastomers obtained with such compositions.

Process for the removal of hydrogen sulfide from a gas mixture by active carbon

Abstract: Hydrogen sulphide is removed from a crude gas by means of activated carbon impregnated with potassium iodide. The crude gas, which also contains free oxygen in a more than stoichiometric quantity, is passed at a pressure in the range from 1 to 200 bar and at temperatures below 100 C through a bed of granular activated carbon, elemental sulphur being formed. The activated carbon has a BET surface area from 500 to 1500 m /g, a potassium iodide content from 0.5 to 5% by weight and grain sizes from 0.5 to 6 mm. The activated carbon is loaded with at least 50% by weight of absorbed elemental sulphur, relative to non- loaded carbon. The regeneration of the activated carbon is carried out at a pressure from 1 to 1.5 bar with hot inert gas at temperatures from 200 to 500 C, which gas is passed through the activated carbon and removes the elemental sulphur. After at least four regeneration treatments, the activated carbon is newly impregnated with potassium iodide.

Structure and properties of porous hypercrosslin ked polystyrene sorbents 'Styrosorb'

Abstract: Hypercrosslinked sorbents %tyrosorb" were obtain- ed by introducing large number of rigid bridges between li- near polystyrene chains in solution or in a highly swollen state. This crosslinking procedure results in a homogeneous The porosity stems from the loose packing of polymer chains in the rigid network. The inner specific surface area of Styrosorbs, when calculated formally in terms of the BET theory, reaches a value of loOO-l3OO m /g, though a more de- tailed analysis reveals the failure of the theory to describe the sorbtion ptoperties of the polymers, The total volume of voids does not exceed 0,5 cm3/g, with an average pore diame- ter of 1.0-1.5 nm. However, the inner surface of the sorbents appears to be easily accessible to both small and large or- ganic molecules due to a cooperative conformational rearran- gement of the network under the influence of the sorbate mo- lecules. The sorption capacity of Styrosorbs with respect to vapours of organic compounds exceeda by far the capacity of known types of polymeric and inorganic sorbents. Styrosorbs efficiently extract non-polar organic compounds from aqueous and polar organic media. They are further useful as column packing materials in size exclusion chromatography of oligo- mers . network which appears to be highly porous when in dry state.

Process for the preparation of sulphur-free iron-oxide- and chromium-oxide-containing catalysts

Abstract: The application relates to a process for the preparation of sulphur-free iron-oxide- and chromium-oxide-containing catalysts having BET surface areas of 20 to 100 m /g and in which more than 80% of the pore volume is in the pore radius range of 30 to 100 nm, an iron(III) oxide prepared from iron carbonyl having a mean grain size below 10 mu m and a BET surface area of greater than 50 m /g and chromium(III) oxide having a mean grain size below 40 mu m and a BET surface area of more than 30 m /g being mechanically mixed as powder or suspension and then tableted.

Process for the preparation of n-alkylated anilines

Abstract: Anilines or N-alkyl-anilines are advantageously reacted with alkyl alcohols or the associated dialkyl ethers at elevated temperature in the gas phase, if a γ-Al2 O3 is used that is prepared by dehydration of an aluminum oxide/hydroxide hydrate and has a BET surface area from 50 to 400 m2 /g and a surface acidity of 5 to 600 mmol H+ /kg.

IR study of chlorination of alumina employing mixtures of gaseous chlorine and carbon monoxide

Abstract: The chlorination of an alumina with BET surface area of 100 m2/g has been studied in situ by transmission IR measurements at about 670 K. The chlorinating gases consisting of Cl2 and CO were employed individually and in equimolar proportion. The IR results do not reveal the presence of a phosgene surface species which could support the only mechanism proposed so far to explain the chlorination. A detailed alternative reaction mechanism is suggested for the high temperature chlorination reaction, taking into account the IR results, together with the known electron donor-acceptor properties of the activated alumina and the reaction gases: Cl2 molecules accept electrons from oxide ions with a lower coordination number on the alumina surface, leading to the formation of Cl−and Oad. While Cl− yields AlCl3, Oad reacts further with CO producing CO2.

Black titanium nitride and process for its preparation

Abstract: A black titanium nitride with a BET surface area of 10 to 80 metres squared per gram and containing from 1 to 10% by weight of oxygen is described. The titanium nitride can be prepared by the reaction of ammonia and a titanium halide in an electric plasma of a non-oxidising gas under conditions which induce recirculation of the gaseous material.

Three Parametric Equations and Their Adaptability (III)

Abstract: The accomodation of a three-Parameter adsorption equation derived on the basis of statistical thermodynamics in the model of localized adsorption for monolayer and non-localized adsorption for the upper adphase over the 1st layer to the experimental adsorption isotherms has been investigated by N2 adsorption isotherms on carbon black with a micropore which is preadsorbed by nonane. The three-parameter adsorption equation agreed well with experimental isotherms in the range of relative pressure from 0.01 to 0.6. These had wider range of agreement than with the BET equation i. e., in a range from 0.05 to 0.2. Accordingly, the upper adphase over the monolayer for the formation in an intermediate relative pressure range after the completion of the monolayer was perceived not to form stacked layers like the localized multilayer proposed by BET theory, but to form preferably a non-localized mobile adphase. The surface areas obtained from the three-parameter adsorption equation, a Huttigtype adsorption equation and BET equation, agreed with each others within 15%, respectively. These surface areas were investigated by comparison of the results from αs-plots of these experimental isotherms. Since the surface areas obtained from the isotherms in the reduction of the micropore amount from αs-plot in the application of each adsorption equations agreed with the outer plane surface areas from the slope of the linear portion in αs-plots, the micropores would be filled up in an extremely low relative pressure range. The surface areas obtained from the three-parameter adsorption equation was perceived to be reasonable.

High surface area alpha-alumina and supercritical fluid synthesis thereof

Abstract: High surface area α-alumina free of transitional aluminas and having a BET surface area greater in the range of about 30 to at least about 100 m2/g, and a method of producing same comprising the step of heating an α-alumina precursor, such as an aluminum hydroxide or a hydrated alumina, with a solvent, such as methanol, under conditions of temperature and pressure that are supercritical for the solvent. The resultant surface area may be controlled by the addition of water to the starting materials.

Surface-Metals Interactions in Fluid Cracking Catalysts During the Upgrading of Vanadium Contaminated Gas Oils

Abstract: Laser Raman and x-ray photoelectron spectroscopy (XPS), together with microactivity testing, x-ray diffraction (XRD) and BET surface area measurements have been used to elucidate the interaction of vanadium with typical constituents of a fluid cracking catalyst. Cracking components like HY or CREY (calcined rare-earth exchanged zeolite Y) are thermally stable in air at 760°C/5h even when loaded with 3–4% V. In the presence of steam, stability is greatly reduced. With less than 1% V, HY collapses with formation of mullite (Al6Si2O13) and silica (tridymite) whereas CREY collapses with formation of cerium orthovanade (CeVO4). The presence of lanthanide ions in the zeolite reduces V-tolerance at hydrothermal conditions. Mullite formation was also observed on V-loaded gels. On steam-aged Kaolin, aluminosilicate gels and HY, vanadium is present mainly as bulk V2O5.

Continuous process for complete removal or organic impurities from and complete decolorization of prepurified wet-process phosphoric acid

Abstract: A continuous process is indicated for complete removal of organic impurities from and complete decolorization of pre-purified wet-process phosphoric acid which has been purified by an extractive method using an organic solvent, freed from residual hydrofluoric acid by steam stripping and treated with hydrogen peroxide at elevated temperature, which comprises mixing the pre-purified wet-process phosphoric acid and the hydrogen peroxide in a mixing zone at a temperature of from 100° to 200° C., preferably 140° to 160° C., and allowing them to react at this temperature for a further 1 to 4 hours, cooling to from 85° to 90° C. the pre-purified wet-process phosphoric acid treated in this way and pumping it at this temperature with exclusion of air firstly through an activated charcoal bed which has been prepared on the basis of peat and has been steam-activated and has a BET surface area of from 800 to 1000 m 2 /g, and subsequently through a silicon carbide and/or graphite bed while maintaining a pumping rate of less than 0.5 m 3 /h of wet-process phosphoric acid per m 3 of activated charcoal bed.

Copper-containing catalyst for low-temperature carbon oxide conversion

Abstract: Copper-containing catalysts for low-temperature conversion at temperatures of from 150 to 300 DEG C and at from 10 to 40 bar which additionally contain aluminium, and zinc, if desired in the form of the compounds or oxides, and are prepared by joint precipitation, the copper-containing catalysts containing potassium and having a BET surface area matched to the potassium content, the potassium content being set to from 0.1 to 3.0% by weight at a BET surface area of from 30 to 160 m /g, and their use for the production of hydrogen and carbon dioxide from carbon monoxide and water.

Spherical hydrophilous silica, process for its preparation and use

Abstract: Spherical hydrophilic silica consisting of compact, solid, non-crystalline particles without internal pores, having a particle size of 0.5 to 10 mu m, preferably 0.5 to 4 mu m, in particular 1 to 3 mu m, having a BET surface area of /g, preferably of 1 to 10 m /g, by heating steam and gaseous silicon tetrachloride separately to a temperature of 300 to 400 DEG C, mixing with one another in a molar ratio of 2:1 to 6.7:1 and reacting the mixture at a temperature of 600 to 1200 DEG C.

The Three-Parametric Adsorption Equation and its Adaptability (IV)

Abstract: Nitrogen adsorption isotherms at 77K on non-porous powders, such as γ-Fe2O3, A1100 and SM and silicon carbide, SiC(P) have been measured. The application of experimental isotherms to the 3-parametric adsorption equation was compared with that of the BET equation. The applicable relative pressure range of the 3-parametric adsorption equation was compared with that of the BET equation. The applicable relative pressure range of the 3-parametric adsorption equation was wider, from 0.05 to 0.65, than that of the BET equation which was in the range from 0.05 to 0.35. The surface areas, ∑T obtained from the 3-parametric adsorption equation showed an agreement within 10% with that from the BET equation, ∑B. Since the straight line in αs-plots of N2 adsorption isotherms were found to pass through the origin of the coordinate, the powders were confirmed to have no micropore. The outer plane surface areas, ∑Tαs and ∑Bαs, were determined from the slope of the straight line in αs-plots of the standard isotherm of N2 on non-porous hydroxylated silica, on the basis of the surface areas by application of the standard isotherm to the 3-parametric adsorption equation and BET equation, respectively. There is a reasonable agreement of ∑T and ∑B with ∑Tαs, and ∑Bαs, respectively, and therefore it will be difficult to determine which surface areas were the most reasonable. However, the surface areas obtained from the measurement of the particle diameter in use of a photograph of a scanning electron microscope showed better and reasonable agreement with the surface areas from the 3-parametric adsorption equation than that from BET equation. Therefore, the 3-parametric adsorption equation seemed to be more reasonable than the BET equation.

Synthesis of Sinterable β‐SiC Powders by a Solid Combustion Method

Abstract: A solid combustion method for obtaining sinterable {beta}-SiC powders from Si and C mixtures is described. The method is similar to the thermal explosion method in which a proper preheating of the reactive mixture enables a substantial increase in the temperature of the mixture, due to the heat of reaction, in a short time. The characteristics of the powders obtained by the method are given. Both a high chemical purity of the powders, which is due to the high temperature of synthesis, and an adequate BET surface area of the powders, obtained after vibratory milling, enable these powders to be used for producing sintered SiC materials.