Showing papers on "BET theory published in 1984"
Book•
19 Jul 1984
TL;DR: In this article, the authors compare the single-point and multi-point methods for surface area analysis with the single point and multipoint methods for measuring porosimetry and gas adsorption.
Abstract: I Theoretical.- 1 Introduction.- 1.1 Real surfaces.- 1.2 Factors affecting surface area.- 1.3 Surface area from size distributions.- 2 Gas adsorption.- 2.1 Introduction.- 2.2 Physical and chemical adsorption.- 2.3 Physical adsorption forces.- 3 Adsorption isotherms.- 4 Langmuir and BET theories.- 4.1 The Langmuir isotherm, type I.- 4.2 The Brunauer, Emmett and Teller (BET) theory.- 4.3 Surface areas from the BET equation.- 4.4 The meaning of monolayer coverage.- 4.5 The BET constant and site occupancy.- 4.6 Applicability of the BET theory.- 4.7 Some criticism of the BET theory.- 5 The single point BET method.- 5.1 Derivation of the single-point method.- 5.2 Comparison of the single-point and multipoint methods.- 5.3 Further comparisons of the multi- and single-point methods.- 6 Adsorbate cross-sectional areas.- 6.1 Cross-sectional areas from the liquid molar volume.- 6.2 Nitrogen as the standard adsorbate.- 6.3 Some adsorbate cross-sectional areas.- 7 Other surface area methods.- 7.1 Harkins and Jura relative method.- 7.2 Harkins and Jura absolute method.- 7.3 Permeametry.- 8 Pore analysis by adsorption.- 8.1 The Kelvin equation.- 8.2 Adsorption hysteresis.- 8.3 Types of hysteresis.- 8.4 Total pore volume.- 8.5 Pore-size distributions.- 8.6 Modelless pore-size analysis.- 8.7 V?t curves.- 9 Microporosity.- 9.1 Introduction.- 9.2 Langmuir plots for microporous surface area.- 9.3 Extensions of Polanyi's theory for micropore volume and area.- 9.4 The t-method.- 9.5 The MP method.- 9.6 Total micropore volume and surface area.- 10 Theory of wetting and capillarity for mercury porosimetry.- 10.1 Introduction.- 10.2 Young and Laplace equation.- 10.3 Wetting or contact angles.- 10.4 Capillarity.- 10.5 Washburn equation.- 11 Interpretation of mercury porosimetry data.- 11.1 Application of the Washburn equation.- 11.2 Intrusion-extrusion curves.- 11.3 Common features of porosimetry curves.- 11.4 Solid compressibility.- 11.5 Surface area from intrusion curves.- 11.6 Pore-size distribution.- 11.7 Volume In radius distribution function.- 11.8 Pore surface area distribution.- 11.9 Pore length distribution.- 11.10 Pore population.- 11.11 Plots of porosimetry functions.- 11.12 Comparisons of porosimetry and gas adsorption.- 12 Hysteresis, entrapment, and contact angle.- 12.1 Introduction.- 12.2 Contact angle changes.- 12.3 Porosimetric work.- 12.4 Theory of porosimetry hysteresis.- 12.5 Pore potential.- 12.6 Other hysteresis theories.- 12.7 Equivalency of mercury porosimetry and gas adsorption.- II Experimental.- 13 Adsorption measurements-Preliminaries.- 13.1 Reference standards.- 13.2 Other preliminary precautions.- 13.3 Representative samples.- 13.4 Sample conditioning.- 14 Vacuum volumetric measurements.- 14.1 Nitrogen adsorption.- 14.2 Deviation from ideality.- 14.3 Sample cells.- 14.4 Evacuation and outgassing.- 14.5 Temperature control.- 14.6 Isotherms.- 14.7 Low surface areas.- 14.8 Saturated vapor pressure, P0 of nitrogen.- 15 Dynamic methods.- 15.1 Influence of helium.- 15.2 Nelson and Eggertsen continuous flow method.- 15.3 Carrier gas and detector sensitivity.- 15.4 Design parameters for continuous flow apparatus.- 15.5 Signals and signal calibration.- 15.6 Adsorption and desorption isotherms by continuous flow.- 15.7 Low surface area measurements.- 15.8 Data reduction-continuous flow.- 15.9 Single-point method.- 16 Other flow methods.- 16.1 Pressure jump method.- 16.2 Continuous isotherms.- 16.3 Frontal analysis.- 17 Gravimetric method.- 17.1 Electronic microbalances.- 17.2 Buoyancy corrections.- 17.3 Thermal transpiration.- 17.4 Other gravimetric methods.- 18 Comparison of experimental adsorption methods.- 19 Chemisorption.- 19.1 Introduction.- 19.2 Chemisorption equilibrium and kinetics.- 19.3 Chemisorption isotherms.- 19.4 Surface titrations.- 20 Mercury porosimetry.- 20.1 Introduction.- 20.2 Pressure generators.- 20.3 Dilatometer.- 20.4 Continuous-scan porosimetry.- 20.5 Logarithmic signals from continuous-scan porosimetry.- 20.6 Low pressure intrusion-extrusion scans.- 20.7 Scanning porosimetry data reduction.- 20.8 Contact angle for mercury porosimetry.- 21 Density measurement.- 21.1 True density.- 21.2 Apparent density.- 21.3 Bulk density.- 21.4 Tap density.- 21.5 Effective density.- 21.6 Density by mercury porosimetry.- References.
1,066 citations
Patent•
BP1
TL;DR: In this article, the vapour phase hydrogenation of carboxylic acid esters to give alcohols is described, where the Group VIII element is ruthenium, nickel, or rhodium and the promoter is introduced on to the carbon as a water stable compound of Group IA, IIA metal, a lanthanide or actinide.
Abstract: The present invention relates to the vapour phase hydrogenation of carboxylic acid esters to give alcohols. More particularly, this invention pertains to a process for the production of an alcohol by hydrogenation of an ester with a hydrogenation catalyst comprising a Group VIII element, a promoter, and a carbon support. This process is characterized in that (1) the Group VIII element is ruthenium, nickel, or rhodium, (2) the promoter is introduced on to the carbon as a water stable compound of Group IA, IIA metal, a lanthanide or actinide, and (3) the carbon has a BET surface area of at least 100 m 2 /g, and a ratio of BET to basal plane surface area not greater than 4:1, and (4) the hydrogenation is carried out in the vapor phase at a temperature in the range 100° C. to 400° C. at a total space velocity of 100 to 120,000.
45 citations
TL;DR: In this paper, a new exothermal peak, located between the γ-FeOOH dehydration and further transformation to hematite, has been detected in the DSC diagrams.
35 citations
TL;DR: In this paper, X-ray diffraction was used to characterize a series of Coz.sbnd catalysts and showed that the catalyst surface contains CoMoO 4 and irreducible Co 2+ ions of tetrahedral symmetry when the CoO concentration is 0 to 6%.
29 citations
TL;DR: In this article, the sintering of coprecipitated nickel alumina catalysts was studied in a 70 hydrogen/30% steam gas flow at a temperature of 700°C and a pressure of 1 bar.
23 citations
TL;DR: In this paper, the authors compared the performance of the two methods in terms of surface area for a single metal oxide and showed that the difference in surface area is not due to adjustment of the surface tension or contact angle between the material and the mercury.
22 citations
01 Mar 1984
TL;DR: In this paper, the adsorption isotherms follow the Langmuir equation above an equilibrium concentration of 2.0 × 10−3 mmoles/liter of Cu2+.
Abstract: Adsorption of Cu2+ on various crystalline modifications of MnO2 at 300°K and in buffered medium of pH 4.4 has been studied. The adsorption isotherms follow the Langmuir equation above an equilibrium concentration of 2.0 × 10−3 mmoles/liter of Cu2+. The isotherms reveal that the δzMnO2 group of samples show the highest sorption capacity followed by the electrolytic γzMnO2 and αzMnO2 group of samples. Beta-MnO2 shows the poorest sorption capacity. Similar is the behavior for release of Mn2+ in solution during the adsorption of Cu2+. It has been observed that there is a direct relationship between the amount of Mn2+ release and the fraction of lower valence manganese present in the samples. Adsorption capacity is also found to be directly related to BET surface area.
17 citations
TL;DR: In this paper, the formation and fine structure of microporous carbons and the nature of adsorption in micropores are discussed and some experimental factors are also considered.
13 citations
TL;DR: In this paper, the surface area of mica and aluminum foil samples was estimated using the adsorption isotherm gradient method using the benzene or toluene vapor at room temperature.
10 citations
01 Aug 1984
TL;DR: In this article, the surface area of polyoxymethylene (POM) is shown to be 150 m2/g, which is the largest surface area known for POM.
Abstract: Single crystals of polyoxymethylene are flat, homogeneous, and essentially uncharged and offer a large specific surface area. Since they can be prepared reproducibly and in large amounts, they constitute a suitable model substrate in systematic adsorption studies. The crystallization procedure is discussed in some detail. The thickness of the crystals is obtained from EM and SAXS measurements, the results being in excellent mutual agreement. Combining this thickness with the crystal density the geometrical surface area is found to be 150 m2/g. This is compared with the surface area obtained by BET analysis of nitrogen adsorption (30 m2/g) and with the surface area that follows from adsorption of polyoxyethylated nonyl phenols from aqueous solution (60 m2/g). The discrepancy in the results is explained in terms of different degrees of aggregation of POM crystals in the dry state and in suspension. Finally, some preliminary results of albumin and sodium polystyrene sulfonate adsorption are discussed.
7 citations
Patent•
19 Nov 1984
TL;DR: In this article, a 1,4-di-substituted benzene with a 1-3C alkylating agent in a gaseous phase is used as a catalyst.
Abstract: PURPOSE:To obtain a 1,4-di-substituted benzene in high reproducibility in high selectivity, by using specific crystalline aluminosilicate zeolite as a catalyst, alkylating a mono-substituted benzene with a 1-3C alkylating agent in a gaseous phase. CONSTITUTION:In preparing a 1,4-di-substituted benzene by alkylating a mono- substituted benzene with a 1-3C alkylating agent in the presence of crystalline aluminosilicate zeolite in a gaseous phase, crystlline aluminosilicate zeolite of zeolite not replaced with ion obtained by hydrothermal synthesis using silica supplying substance, alumina supplying substance, alkali metal supplying substance, organic cation or organic cation precursor, followed by air combustion, having >=10mol ratio of silica/alumina, 1-15 control index, and 100-250m /g BET surface area by nitrogen adsorption, is used as a catalyst. Especially the catalyst has preferably properties shown by the table in diffraction X-ray diagram.