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Showing papers on "Activated alumina published in 1979"


Patent
17 Sep 1979
TL;DR: In this paper, a method and filter bed for removing impurities from liquids wherein the filter bed comprises a mixture of treated filter aid material and an active particulate material having opposite surface charges in aqueous suspension.
Abstract: A method and filter bed for removing impurities from liquids wherein the filter bed comprises a mixture of treated filter aid material and an active particulate material having opposite surface charges in aqueous suspension. The filter aid material has been treated to produce the desired surface charge. The identity of the active particulate material depends on the application. Examples are organic polymeric absorbents, zeolites, bentonite, zirconium oxide, zirconium phosphate, activated alumina, ferrous sulfide, activated carbon and diatomaceous earth.

68 citations


Patent
22 Oct 1979
TL;DR: In this article, a porosity of 75-95% was achieved by covering surfaces of cell strands of a ceramic body skeleton having a bulk specific gravity of 0.25-0.55 with 3-40% by weight per the weight of the skeleton of an activated alumina layer.
Abstract: A ceramic porous body useful as a filtering material for molten metal is disclosed. The ceramic porous body, consisting essentially of cordierite, alumina and silica, is formed by covering surfaces of cell strands of a ceramic porous body skeleton having a bulk specific gravity of 0.25-0.55 with 3-40% by weight per the weight of the skeleton of an activated alumina layer and has an average diameter of interconnected voids of 0.3-5.0 mm, a pressure loss of 0.3-30.0 mm as a water-gauge pressure when passing air through the body of 1 cm thick at a rate of 1 m/sec., a microsurface area of not less than 10 m 2 /g and a porosity of 75-95%.

49 citations


Journal ArticleDOI
TL;DR: The results of the present study indicate that for optimum removal of fluoride ion the system pH should be maintained at pH5.1 as discussed by the authors, and that at the optimum pH condition, the rate of fluoride adsorption onto activated alumina increases as the ratio of the fluoride ion concentration to activated aluminina dosage decreases.
Abstract: Adsorption of fluoride ion from aqueous solution by activated alumina was carried out in six 2-l reactors under different pH values and ratios of initial fluoride ion to activated alumina. The results of the present study indicate that for optimum removal of fluoride ion the system pH should be maintained at pH5. Also, at the optimum pH condition, the rate of fluoride adsorption onto activated alumina increases as the ratio of fluoride ion concentration to activated alumina dosage decreases. However, no remarkable change in adsorption rate constant was found when the ratio indicated previously exceeded 10\u-² mg/mg of fluoride ion of activated alumina. Fluoride ion adsorption could be modeled by the Langmuir Isotherm.

38 citations


Patent
30 Nov 1979
TL;DR: In this paper, it has been discovered that silica may be effectively and selectively removed from such waste-water streams without the consequential removal of its beneficial chemical conditioning additives by passing such water over activated alumina and thereafter returning it to the system from which it was withdrawn thereby maintaining the silica concentration in the system below its scale formation level.
Abstract: Industrial waste-water, particularly cooling water containing water conditioning chemical additives, which heretofore has been discharged to the environment as blowdown because of high silica content, may now be treated for selective silica removal to condition it for reuse in industrial systems. It has been discovered that silica may be effectively and selectively removed from such waste-water streams without the consequential removal of its beneficial chemical conditioning additives by passing such water over activated alumina and thereafter returning it to the system from which it was withdrawn thereby maintaining the silica concentration in the system below its scale formation level.

33 citations


Patent
11 Aug 1979
TL;DR: In this article, a three-way catalyst for cleaning exhaust gas from internal cumbustion engine, an activated alumina of an ignition loss of 5-20%, obtained by quickly dehydrating aluminium hydroxide in a high-temperature gas, is mixed with cerium oxide or cerium hydroxides in an amount of 10-18% (as CeO2 of a purity of 90% or more), granulated, cured in a saturated steam, dried, and then baked at 800-1,100 deg.
Abstract: PURPOSE:To manufacture a CeO2-containing catalyst having an oxygen storing effect, by a procedure in which activated alumina obtained by quickly dehydrating aluminium hydroxide is mixed with cerium oxide, granulated, cured, and then baked to obtain a three-way catalyst. CONSTITUTION:As a three-way catalyst for cleaning exhaust gas from internal cumbustion engine, an activated alumina of an ignition loss of 5-20%, obtained by quickly dehydrating aluminium hydroxide in a high-temperature gas, is mixed with cerium oxide or cerium hydroxide in an amount of 10-18% (as CeO2 of a purity of 90% or more), granulated, cured in a saturated steam, dried, and then baked at 800-1,100 deg.C. The catalyst thus obtained, containing CeO2 having an oxygen storing effect,can clean NOx, CO, and hydrocarbons effectively and concurrently.

9 citations


Patent
19 Jun 1979
TL;DR: In this paper, a process for preparing alumina suitable for layer chromatography was described, and the alumina was prepared in accordance with the invention in such a manner that an aluminium trinydroxyde containing 34 to 37% by weight of bayerite, 3 to 5% by value of pseudoboehmite and 60 to 62% of amorphous aluminium trihydroxide was heated at 300° C. to 400° C for 2 to 4 hours.
Abstract: The invention relates to a process for preparing alumina being suitable for layer chromatography. The alumina suitable for layer chromatography is prepared in accordance with the invention in such a manner that an aluminium trinydroxyde containing 34 to 37% by weight of bayerite, 3 to 5% by weight of pseudoboehmite and 60 to 62% by weight of amorphous aluminium trihydroxide is heated at 300° C. to 400° C. for 2 to 4 hours. The activated alumina thus produced is snow-white, has a large specific surface and its average grain size is within the range between 8 and 20 μm. The product complies with the requirements of layer chromatographical technique.

7 citations


Patent
15 May 1979
TL;DR: In this paper, the surface of a catalyst obtained by supporting noble metals, e.g., Pt, Rh, etc., on an activated alumina support is thinly coated with a porous activated alumina composed mainly of gamma-alumina in a thickness of 15 microns or less.
Abstract: PURPOSE: To prevent the lowering of catalyst function by suppressing the passage of vitrifiable components by thinly coating activated alumina on an activated alumina on which noble metals as cleaning catalysts for automobile exhaust gas are supported. CONSTITUTION: In order to obtain a catalyst subjected to a phosphorus-poisoning prevention treatment particulary for cleaning the exhaust gas of automobile, the surface of a catalyst obtained by supporting noble metals, e.g., Pt, Rh, etc., on an activated alumina support is thinly coated with a porous activated alumina composed mainly of gamma-alumina in a thickness of 15 microns or less. Thus, the catalyst so coated allows the passage of exhaust gas but prevents the passage of vitrifiable components. Therefore, the lowering of the catalytic function due to phosphorus poisoning can be prevented. COPYRIGHT: (C)1980,JPO&Japio

1 citations


Patent
07 Mar 1979
TL;DR: In this article, the authors propose to simply and effectivly regenerate activated activated alumina particles whose activity had been lowered by adsorption of silicic acid, by treating the particles with and or alkali to elure the silic acid followed by heat treatment.
Abstract: PURPOSE:To simply and effectivly regenerate activated alumina particles whose activity had been lowered by adsorption of silicic acid, by treating the particles with and or alkali to elure the silicic acid followed by heat treatment.

1 citations


Patent
14 Apr 1979
TL;DR: In this paper, a transitive transitive alumina carrier is used to provide a highly heat resistant catalyst having a long life used in simultaneous removal of NOx CO and HC, and obtd.
Abstract: PURPOSE:To provide a highly heat resistant catalyst having a long life used in simultaneous removal of NOx CO and HC, and obtd. by supporting Rh or Rh and one or more kinds of other platinum group metals, and one or more kinds of metals showing a plurality of oxidized states on a transitive alumina carrier in which at least alpha-alumina is detected through X-rays. CONSTITUTION:alpha-alumina base carrier or activated alumina with a relatively large specific area is calcined to prepare a spherical transitive alumina carrier in which at least alpha-alumina is detected through X-rays. On this carrier are then supported 0.01g of Rh to 1l of packed catalyst or more than 0.02g of Rh and other platinum group metals, and more than 0.01mol of O2 storage components such as Ce, Fe, Cu and Co. The resulting catalyst is used in simultaneous removal of NOx, CO, HC, etc. contained in exhaust gas of car esp. equipped with an internal combustion engine and it has superior heat resistance.

1 citations



Patent
20 Dec 1979
TL;DR: Granulated activated alumina is prepd. by decomposing alumina trihydrate by contacting it with a fluidized bed at 350-600 degrees C for 0.05-0.2 seconds to form amorphous hydroxide; mixing the hydroxides with H2O to form an aq. suspension contg. at 400-600 degree C.
Abstract: Granulated activated alumina is prepd. by (a) decomposing alumina trihydrate by contacting it with a fluidized bed at 350-600 degrees C for 0.05-0.5, esp 0.05-0.2, seconds to form amorphous hydroxide; (b) mixing the hydroxide with H2O to form an aq. suspension contg. 100-500g/litre calculated as Al oxide; (c) hydrating the hydroxide by heating at 20-100 degrees C and at pH 5-12 for 0.5-10 hours. This is followed by (d) treating with an acid which can form H2O sol. basic salts with Al at 20-150 degrees C; (e) granulating, drying at 20-150 degrees C and calcining the prod. at 400-600 degrees C. The activated prod. is used as an adsorbing material, a catalyst, or a support for active components in the chemical and petrochemical industry. Using a fluidised bed decreases the decompsn. temp. also the specified hydration conditions make it possible to modify within a wide range the pore structure of the end prod.