Showing papers on "BET theory published in 1987"
TL;DR: In this paper, the hcp and fcc phases of Mo2C and Mo2N have been prepared and characterized, and the fcc phase has been shown to be polycrystalline and has a high degree of crystallinity, a BET surface area of about 180 m2/g and pores about 17 A in diameter.
124 citations
TL;DR: In this paper, the authors conducted hydrogen adsorption studies at 78 K and pressures up to 40 atmosphere on nine commercial activated carbon samples and found that the amount of hydrogen was increased with increasing surface area.
103 citations
TL;DR: In this paper, the surface charge ( sigma 0)-pH data of a synthetic pure crystalline gibbsite suspension were analyzed with a recently proposed one-step charging model for proton adsorption (one-pK model).
Abstract: Titration curves of a synthetic pure crystalline gibbsite suspension have been made at three NaCl levels. The synthesized gibbsite is characterized by TEM, TGA and X-ray diffraction. The overall BET surface area and the surface area of the edges of the hexagonal crystals are determined. The surface structure of gibbsite is discussed. The surface charge ( sigma 0)-pH data are analysed with a recently proposed one-step charging model for proton adsorption (one-pK model). Analysis of the data suggests that the singly coordinated surface hydroxyls are probably the dominant reactive surface group. Considering these groups as reactive only the titration data could be fitted well with the one-pK model if it is extended with pair formation. Only two adjustable parameters are needed, the Stern layer capacitance and the pair formation constant. Analysis of titration data of aluminium oxides, as presented in recent literature, showed that all sigma 0-pH curves could be described rather well with one and the same set of two parameters, the capacitance of the Stern layer and the pair formation constant. The difference in proton adsorption behaviour between different aluminium (hydr)oxides is mainly caused by differences in the site distribution and the site densities of the aluminium (hydr)oxides involved. The results suggest that pair formation should be taken into account. (Abstract retrieved from CAB Abstracts by CABI’s permission)
78 citations
TL;DR: The gravimetric estimation of CO2-evolved, FT-IR monitoring of the rate of formation of surface species, as well as several other measurements during the n-hexane soot/ozone reaction, has led to the conclusion that soot is a layered structure whose layers are chemically bonded, unlike the graphite structure where the layers are ordered by van der Waals forces as discussed by the authors.
Abstract: The gravimetric estimation of CO2-evolved, FT-IR monitoring of the rate of formation of surface species, as well as several other measurements during the n-hexane soot/ozone reaction, has led to the conclusion that soot is a layered structure whose layers are chemically bonded, unlike the graphite structure where the layers are ordered by van der Waals forces. Fourier transform infrared spectroscopy, electrochemical analysis, microgravimetry, scanning electron microscopy (SEM), and the classical BET surface area determination technique have been employed in this work.
53 citations
TL;DR: The double-layer properties of colloidal RuO2, prepared by thermal decomposition of RuCl3 at 420°C, have been studied by potentiometric acid-base titrations in combination with electrophoretic mobility measurements as mentioned in this paper.
42 citations
TL;DR: In this paper, a direct synthesis of alcohols from syngas on Ru Mo Na/Al 2 O 3 catalysts was investigated at 255°C under 86 kg cm −2.
31 citations
TL;DR: In this article, the surface area and pore structure of Raney copper catalysts were measured at temperatures from 1 to 50°C and it was found that prolonged contact of leached porous copper with caustic solution resulted in decreased BET surface area, increased pore diameters and increased copper crystallite sizes whilst the pore volume of the material remained constant.
19 citations
TL;DR: In this paper, various carbon blacks differing in particle size and surface area, amongst other properties, were used to prepare carbon black composites by mixing the carbon particles with a poly(furfuryl alcohol) binder and subsequently carbonizing the binder material at elevated temperatures.
18 citations
TL;DR: In this paper, solid-state magic angle spinning (MAS) and cross-polarization (CP)-MAS 29 Si NMR spectroscopy was used to monitor polycondensation in alkoxide-derived silica gels during thermal treatment from 25 to 800°C.
17 citations
Patent•
16 Dec 1987
TL;DR: In this paper, the authors proposed a method to improve moisture absorption propertities of a catalyst and to prevent deterioration of catalytic activity due to water by carrying Fe, Co, Ni, Mn, Cu, Cr, Sn and Ce together with Pt or Pd on an alumina carrier.
Abstract: PURPOSE:To improve moisture absorption propertities of a catalyst and to prevent deterioration of catalytic activity due to water by carrying Fe, Co, Ni, etc., together with Pt or Pd on an alumina carrier nonincorporating a narrow pore having diameter not larger than 110Angstrom . CONSTITUTION:A catalyst for removing carbon monoxide is formed by carrying at least one kind selected from a group consisting of Fe, Co, Ni, Mn, Cu, Cr, Sn and Ce together with Pt or Pd on an alumina carrier practically nonincorporating a narrow pore having diameter not larger than 110Angstrom . The alumina carrier having fine narrow pores of 110-120Angstrom and BET surface area not larger than 120m /g which is obtained by calcining alumina particles at the temp. not lower than about 850 deg.C is preferably used. The obtained catalyst is excellent in resistance to moisture absorption properties and little in effect due to water contained in gas and holds high oxidative capacity of carbon monoxide without causing the change thereof with time due to moisture contained in the gas.
12 citations
TL;DR: In this paper, a new method for the preparation of catalysts by means of impregnation is described for obtaining a homogeneous distribution of the active material within preshaped support particles.
Abstract: A new method is described for the preparation of catalysts by means of impregnation. The technique is especially suitable for obtaining a homogeneous distribution of the active material within preshaped support particles. The possibilities of the new procedure are illustrated by impregnation of preshaped α-alumina pellets with various organometallic Sncomplexes. After calcination in air the size and distribution of the resulting SnO2 particles and the surface area and porous structure of the catalysts were investigated by several complementary techniques such as BET surface area measurements, mercury porosimetry, X-ray diffraction, electronmicroscopy and temperature-programmed reduction. It proved possible to control the mean particle size and the porosity within narrow limits.
Patent•
07 May 1987
TL;DR: In this article, a process for decreasing the content of nitrogen oxides in flue gases with a catalyst is described, which consists of contacting the flue gas with a catalytic catalyst.
Abstract: A process for decreasing the content of nitrogen oxides in flue gases. The process comprising contacting the flue gases with a catalyst. The catalyst contains at least one of the metals titanium, zirconium, vanadium, tungsten, molybdenum, or cerium in the form of one or more of their oxides combined with a silicate with a layer structure (layer silicate) comprising acid-activated kaolin. The crystalline layer structure of the acid-activated kaolin is essentially retained, while being not yet X-ray amorphous. The acid activation increases the BET surface area at least 15% and preferably at least 50% in terms of the BET surface area of the kaolin before acid activation. The atomic ratio of the silicon in the acid-activated kaolin to the metal in the oxide is from 0.2 and 50 and preferably from 0.4 to 25.
Patent•
17 Dec 1987
TL;DR: In this paper, a silver catalyst containing lithium and cesium as promoters for the direct oxidation of ethylene with oxygen to give ethylene oxide is applied to 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 containing lithium and cesium as promoters for the direct oxidation of ethylene with oxygen to give ethylene oxide is applied to 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 0.4 to 0.8 m 2 /g, a pore volume of not less than 0.45 ml/g, the pores being equally accessible to cold and warm water, a bulk density of less than 700 kg/m 3 and a shape which, in the reactor, provides a geometrical surface area of not less than 600 m 2 /m 3 , on which more than 13% by weight of silver are applied as active component and more than 115 kg of silver are available per m 3 of reactor, and from 100 to 300 ppm by weight of lithium and from 200 to 600 ppm by weight of cesium are present as promoters. A process for the preparation of the silver catalyst and its use for the oxidation of ethylene are described.
Patent•
27 Oct 1987
TL;DR: In this article, a slurry of boehmite having a specified BET surface area on a fireproof carrier, forming a wash coat by drying and calcining, and supporting a catalytically active material on the wash coat.
Abstract: PURPOSE: To increase activity at low temp. by sticking a slurry of boehmite having a specified BET surface area on a fireproof carrier, forming a wash coat by drying and calcining, and supporting a catalytically active material on the wash coat. CONSTITUTION: Boehmite having 1W100m 2 /g BET surface area is stuck on a fireproof carrier having a monolithic structure in the form of a slurry and a wash coat is formed by drying and calcining. A catalytically active material is then supported on the wash coat to produce a catalyst for purification of waste gas. The drying is preferably carried out with hot air at 30W100°C because rapid treatment is enabled and the calcining is preferably carried out at 300W600°C for several ten minWseveral hr in the air. A Pt family metal is suitable for use as the catalytically active material. COPYRIGHT: (C)1989,JPO&Japio