Showing papers on "Activated alumina published in 1992"

Determination of chromium(III) and chromium(VI) in water using flow injection on-line preconcentration with selective adsorption on activated alumina and flame atomic absorption spectrometric detection

Abstract: A rapid and sensitive method for the species-selective determination of chromium(III) and chromium(VI) in water samples by flame atomic absorption spectrometry using online preconcentration on a microcolumn packed with activated alumina (acidic form) has been developed. Sequential species-selective sorption was possible by using the Clark-Lubs systems with pH 7 for Cr(III) and pH 2 for Cr(VI). The preconcentrated species were eluted directly from the column to the nebulizer-burner system using 1.0 mol/L nitric acid and 0.5 mol/L ammonia for Cr(III) and Cr(VI), respectively

Removing Selenium(IV) and Arsenic(V) Oxyanions with Tailored Chelating Polymers

Abstract: The need for selective sorption of trace concentrations of toxic Se(IV) and As(V) oxyanions, especially in the presence of competing high concentrations of sulfate ions, is well recognized. In this regard, previous investigators have shown the advantages as well as shortcomings of the fixed-bed sorption process when activated alumina or strong-base polymeric anion exchangers are used as sorbents. The present study reports the sorption behaviors of a newly identified sorbent that, in terms of composition, is a specialty chelating polymer with immobilized Cu(II) present at the sorption sites. Experimental results with the new sorbent show higher selenite and arsenate selectivities over competing sulfate ions. Anion exchange accompanied by Lewis acid-base interactions are the underlying reasons for the new sorbent’s enhanced affinities toward arsenates and selenites. In several ways, the new sorbent can complement the shortcomings of activated alumina and other strong-base anion exchangers.

Method and apparatus for filtration with plural ultraviolet treatment stages

Abstract: An improved filtration system involving the use of ultraviolet irradiation, ozonation, chlorination, reactive filtration media, chemical treatment, compressed air aeration, air emission control, and central flow control is described. The process system and apparatus of the present invention mainly include a liquid pump, an ultraviolet pretreatment means, a central flow control, an air emission control means, a reactive pressure filter, a process tank, at least one chemical feeder means, an ultraviolet post-treatment means, and an aeration means. The filter media are of reactive type, including diatomaceous earth, granular activated carbon, fibrous activated carbon, granular metal medium, greensand, neutralizing sand, silica sand, activated alumina, ion exchange resins, polymeric adsorbents, chemical treated adsorbents, manganese oxide, coal, porous plastic medium, porous stainless steel medium, porous ceramic medium, bacteriostatic filter medium, porous paper filter medium, porous carbon filter medium, coalescing filter medium, fiberglass filter medium, or combinations thereof. The process tank contains and handles regenerating chemicals, flocculating chemicals, filter aids, or recirculating water. The reactive filter media of this invention are regenerated by either chemical reactions or aeration for reuse to prolong the filter media's service life and to reduce the operation and maintenance costs. Said air emission control means is provided when compressed air aeration is applied to said pressure filter for regeneration of said reactive filter media. The apparatus of this invention is compact and simple, and can cost-effectively remove suspended, dissolved, volatile, radioactive and living contaminants from a contaminated liquid.

Catalyst for purifying automotive exhaust gas

Abstract: An exhaust gas purifying catalyst for simultaneous removal of carbon monoxide, hydrocarbons and nitrogen oxides from an exhaust gas from an internal-combustion engine, having carried on a monolithic carrier a mixture comprising a catalytically active component comprising 0.5 to 30 g of palladium, 0.1 to 50 l g of an alkaine earth metal oxide, 10 go 150 g of cerium oxide, and 0.1 to 50 g of zirconium oxide and 10 to 300 g of an activated alumina.

Oxidation catalyst and method of use

Abstract: Oxidation catalyst compositions include a catalytic material having a BET surface area of at least about 10 m2/g and consisting essentially of a combination of bulk ceria and a bulk second metal oxide which may be one or more of titania, zirconia, ceria-zirconia, silica, alumina-silica and α-alumina. The combination may optionally also include activated alumina having a BET surface area of at least about 10 m2/g. The ceria, second metal oxide and optional activated alumina may be mixed together or provided as discrete layers. Optionally, one of platinum or palladium metal may be dispersed on the catalytic material provided that the platinum, when used, is used in limited amounts to preclude excessive oxidation of SO?2? to SO3. The catalyst compositions may be used for oxidation of oxidizable components in a gas-borne stream, e.g., in a method to treat diesel engine exhaust by contacting the hot exhaust with the catalyst composition to promote the oxidation of the volatile organic fraction. The optional inclusion of platinum or palladium promotes the oxidation of gas phase components, e.g., hydrocarbons and carbon monoxide.

Catalytic body and process for producing the same

Abstract: A catalytic body contains a base material and, formed on the surface thereof, a catalytic coating layer containing activated alumina, zeolite, a platinum group metal and an inorganic binder. By alternately repeating the step of adsorption of odor components with zeolite and alumina under non-heating condition and the step of heat-regeneration of the zeolite and alumina and catalytic decomposition of odor components under heating condition, offensive odors can be continuously removed over a long period and without excessively raising the temperature in the surroundings of the catalytic body.

Catalyst for decomposition of nitrous oxide

Abstract: PURPOSE:To attain excellent peculiar effects such as a very slight change with the lapse of time as well as to enable efficient catalytic decomposition of N2O in exhaust gas by carrying iridium and at least one among Nb2O5, Tie2 and ZrO2 on a hydrophobic carrier. CONSTITUTION:This catalyst for decomposition of nitrous oxide is a catalyst obtd. by carrying iridium and one or more kinds of oxides selected among Nb2O5, TiO2, and ZrO2. on a hydrophobic carrier such as silica gel, activated alumina or silica-alumina. When this catalyst is produced, the hydrophobic carrier is immersed in an aq. soln. of iridium chloride for a certain time to impregnate the noble metal and the carrier is dried and further immersed in an aq. soln. of one or more among niobium chloride, titanium sulfate and zirconyl sulfate for a certain time to impregnate these precursors of oxides. The carrier is then dried, fired at 300-500 deg.C for 3-5hr and subjected to reduction treatment at 400-500 deg.C for 3-5hr in a flow of gaseous H2.

Epoxidation using hydrogen peroxide and tungsten catalysts

Abstract: Alkenes can be epoxidised with hydrogen peroxide using a homogeneous heavy metal catalyst, but discharge of spent reaction mixtures releases the heavy metal in the environment. The problem can be ameliorated by selecting a heterogeneous catalyst system comprising a tungsten-containing heteropolyacid supported on selected Group IIa, IIb, IIIb, IVa or IVb inorganic supports or on a strong basic resin, which catalyst has either been calcined after impregnation or in the impregnation stage an alcoholic solution of the heteropolyacid is employed and by employing a nitrilo or oxygenated polar solvent reaction medium. A number of preferred heteropolyacids satisfy the empirical formula M3/nPWwMO12-wO40 in which w represents an integer of at least 1, M represents a counterion and n its basicity. Preferred supports include activated alumina, calcined at 400 to 600° C and cross-linked quaternary ammonium-substituted polystyrene resins. The most preferred catalysts are made by impregnating an inorganic support with a methanol solution of the heteropolyacid to a desired loading of active material on the support and subsequently calcining the loaded support at 400 to 600° C. Preferred reaction media include acetonitrile and tertiary butanol.

Ceria-alumina oxidation catalyst and method of use

Abstract: Oxidation catalyst compositions include a catalytic material containing ceria and alumina each having a surface area of at least about 10 m2/g, for example, ceria and activated alumina in a weight ratio of from about 1.5:1 to 1:1.5. Optionally, platinum may be included in the catalytic material in amounts which are sufficient to promote gas phase oxidation of CO and HC but which are limited to preclude excessive oxidation of SO?2? to SO3. Alternatively, palladium in any desired amount may be included in the catalytic material. The catalyst compositions have utility as oxidation catalysts for pollution abatement of exhausts containing unburned fuel or oil. For example, the catalyst compositions may be used in a method to treat diesel engine exhaust by contacting the hot exhaust with the catalyst composition to promote the oxidation of the volatile organic fraction component of particulates in the exhaust.

Exhaust gas purification catalyst

Abstract: PURPOSE:To prevent the formation of an alloy with Pd and Rh or Pt when used at high temperature and thereby prevent performance deterioration by forming a layer which does not contain precious metal components between a layer containing Pd and a layer containing Pt and/or Rh. CONSTITUTION:The subject catalyst is composed of the first layer containing Pd and activated alumina, the second layer containing activated alumina which does not contain precious metal, and the third layer containing Rh and/or Pt and activated alumina on monolithic carrier base as a catalyst for exhaust gas purification. Thus, the mutual action between Pd, and Pt and/or Rh is prevented by an intermediate layer which does not contain precious metal, so that the production of an alloy during use at high temperature is restricted. Subsequently, catalytic performance deterioration is minimized.

Catalyst for removing nitrogen oxide

Abstract: PURPOSE:To obtain a catalyst having high NOx decomposition capacity by applying and supporting catalytic components containing activated alumina having W and Cu supported thereon and specific zeolite on a honeycomb carrier having a monolithic structure CONSTITUTION:An aqueous mixture of a W-source such as tungsten oxide and a Cu-source such as an inorg or org salt of copper is mixed with activated alumina and the resulting mixture is dried and calcined to obtain a catalytic component A having W and Cu supported thereon in predetermined amounts Separately, one or more kinds of components selected from H-type ferrite, H-type mordenite and H-type ZSM-5 are selected to be set to a catalyst component B The catalyst components A, B, are subjected to wet grinding in a predetermined ratio to prepare a slurry which is, in turn, infiltrated in a honeycomb carrier Subsequently, the excessive slurry is removed by a means such as the blow of compressed air and the impregnated carrier is dried to obtain a catalyst for removing nitrogen oxide The obtained catalyst is excellent in the decomposition capacity of NOx and has high temp heat resistance

Catalyst excellent in heat resistance for purifying exhaust gas of internal combustion engine and production thereof

Abstract: PURPOSE: To enhance capacity for keeping purifying activity by forming an active layer containing a platinum group element, activated alumina, cerium oxide, a barium compound and a zirconium compound on a support. CONSTITUTION: Catalyst components consisting of a platinum group element, activated alumina, for example, α-alumina with a specific surface area of 10-300m 2 /g, cerium oxide, a barium compound such as barium hydroxide and a zirconium compound such as zirconium oxide are supported on a support having a monolithic structure. The support is formed into a honeycomb shape from refractory metal oxide such as cordierite. The wts. of the platinum group element, activated alumina, cerium oxide, the barium compound and the zirconium compound per 1L of a catalyst are respectively set to 0.02-2g, 30-200g, 10-150g, 0.1-20g (as barium oxide) and 0.1-30g. COPYRIGHT: (C)1993,JPO&Japio

Arsenic and selenium removal from fly ash leachate

Abstract: A bench-scale study of fly ash leachate evaluated the potential for iron coprecipitation and activated alumina adsorption to meet National Pollution Discharge Elimination System (NPDES) limits for arsenic and selenium. Study results showed that arsenic can be removed effectively from fly ash leachate in the laboratory by both iron coprecipitation and activated alumina. Both processes required careful control to remove selenium. For activated alumina treatment, the batch studies empolyed three mesh sizes of activated alumina. All three mesh sizes provided effluent well below the required limit for arsenic. However, only the 80x200 mesh test met the selenium limit. The continuous flow testing showed good results for arsenic,and selenium concentrations were very close to the permit limit. The results of the study provide a prediction of effluent quality and also provide information for conceptual design parameters. Detailed pilot studies will be needed to better define the design parameters.

Verfahren zur Oxidation von Arsenat(III) in der Trinkwasseraufbereitung

Abstract: The Germain drinking water standard for arsenic will be reduced from 40 to 10 μg/l in 1996. Some groundwater plants containing geogenic arsenic will probably require removal of the arsenic. While pentavalent As is quite effectively removed by precipitation with ferric salts or adsorption on activated alumina, As(II) must be oxidized before removal. Simple but specific processes were sought for this oxidation, and two techniques without dosing of chemicals were investigated; UV-irradiation and catalytic oxidation by powdered activated carbon

Activated alumina for removing heavy metal and production of silver nitrate using the same

Abstract: PURPOSE:To remove heavy metals from a silver nitrate soln and to obtain high-purity silver nitrate by bringing the activated alumina having >=8 surface acidity and consisting of the grains having =8 surface acidity and consisting of the grains having <=50Angstrom average pore diameter, and the heavy metals are removed from the soln The activated alumina having basic surface acidity absorbs heavy metals more easily than that having acidic surface acidity, and the basic activated alumina with the pore size smaller than a specified value is effectively used Namely, there is provably a correlation between the surface acidity of the activated alumina grain and pore diameter and the properties of the elements occluded in the pore in terms of the periodic table High-purity silver nitrate is thus obtained by a continuous process by using the activated alumina highly adsorptive to heavy metals

Manufacture of catalyst for purifying exhaust gas

Abstract: PURPOSE:To improve catalytic performance by allowing an oxide as a preliminary processing material to be borne on a thin wall support with a low coefficient of water absorption of a monolithic structure and then further allowing a specified catalytic component to be borne. CONSTITUTION:A specified catalytic component is allowed to be borne after an oxide as a preliminary processing material is allowed to be borne on a thin wall support with a low coefficient of water absorption of a monolithic structure. The oxide with a low coefficient of water absorption of a monolithic structure consists of a fireproof metal oxide with a coefficient of water absorption of 12wt.% or lower. The most favorably used support is a honeycomb support of cordierite. The thin wall design is for reducing a pressure loss when the catalyst is mounted on a vehicle and the actual wall thickness is 90% or lower than that of the conventional catalyst. The preliminary processing material is selected from among activated alumina, activated silica, cerium oxide, ziconium oxide and titanium oxide. The catalytic component is platinum element, activated aluminum or cerium oxide. Thus catalytic performance is enhanced.

Production of catalyst for purification of exhaust gas

Abstract: PURPOSE:To obtain a catalyst for purification of exhaust gas causing no deterioration of the catalytic performance even after use at a high temp. for a long time by ionizing a noble metal, accelerating the resulting ions to a high speed with an accelerator and implanting the ions into the surface of activated alumina. CONSTITUTION:A catalytic metal is supported on a flat metallic sheet coated with activated alumina by an ion implantation method by which particles to be added are ionized in vacuum of Pa and the resulting ions are accelerated to several keV-several MeV and implanted into a solid substrate. The depth of the ions implanted depends on the kinds of the ions and the substrate but is controlled by acceleration energy. The amt. of the particles implanted is controlled by the current density of ion beams and implantation time. Since noble metal ions are accelerated to a high speed with an accelerator and implanted into the surface of the activated alumina to obtain a catalyst for purification of exhaust gas, the noble metal is perfectly fixed in the surface of the alumina on an atomic level and sintering due to the transfer of the noble metal on the alumina is not caused.

Aldehyde decomposing catalyst for purifyying exhaust gas

Abstract: PURPOSE:To obtain a catalyst excellent in heat resistance and efficiently decomposing aldehyde in the exhaust gas discharged from a combustion engine using oxygen-containing fuel at low temp. CONSTITUTION:A catalyst layer consisting of composite oxide represented by chemical formula Ce1-xZrxCu1-yAuyO3-sigma (wherein x is 0.1 or 0.2, y is 0.02-0.04 and sigma is 1.0 or less), cerium-containing activated alumina oxide having O2 storage capacity and a large specific surface area is provided on a carrier base material.

Ceramic sheet with catalyst and its production

Abstract: PURPOSE: To enhance the efficiency of combustion and workability by specifying the average particle diameter of an inorg. oxide carrying a noble metal catalyst in the sheet for oxidation decomposition of an org. compd. CONSTITUTION: When a ceramic sheet with a catalyst is composed essentially of ceramic fibers 1 such as alumina fibers, a noble metal catalyst 5 and an inorg. oxide 4 for carrying the catalyst 5, e.g., activated alumina, the average particle diameter of the inorg. oxide 4 is regulated to ≤6μm, preferably ≤1.5μm. In the case of >6μm average particle diameter, flocculating power lowers and powder of the inorg. oxide is liable to fall. In the case of ≤1.5μm average particle diameter, strength can sufficiently be maintained without using an inorg. binder 2. When the inorg. binder 2 is used, colloidal silica or colloidal alumina is used. COPYRIGHT: (C)1994,JPO&Japio

Production of aqueous slurry of activated alumina and activated alumina adsorption column

Abstract: PURPOSE:To obtain the title slurry excellent in fluidity by dispersing activated alumina particles in water and adjusting the pH level of the resultant aqueous slurry to a specified value to prevent flocculation of the activated alumina particles in the slurry. CONSTITUTION:Firstly, activated alumina particles are dispersed in water to produce an aqueous slurry of said alumina particles. Thence, the pH level of this slurry is adjusted to 2-6 to prevent flocculating the activated alumina particles in the slurry. And, this aqueous slurry is introduced into an adsorption column using e.g. a slurry pump to make the objective adsorption column packed with the activated alumina for use in purification. Thus, because of excellent fluidity of the above aqueous slurry, said adsorption column can be made in good workability. When such activated alumina as to be >=8 in surface acidity is used, the present method will be particularly effective.

Removing method for nitrogen oxide in gas

Abstract: PURPOSE:To remove nitrogen oxides in gas by using a solid catalyst under coexistence of an org. compd. CONSTITUTION:Nitrogen oxides in gas are removed by bringing the gas containing nitrogen oxides into contact with a solid catalyst under coexistence of an org. compd. As for the org. compd., methyl tert-butylether is directly added to the gas. Further, the solid catalyst consists of at least one element of Rh, Ru and Pt deposited on an activated alumina.

Preparation of alumina carrier

Abstract: PURPOSE:To obtain an alumina carrier having micropores and enhanced in mechanical strength by molding an activated alumina powder adjusted to specific moisture content under specific pressure and ageing the molded matter at specific temp. before drying and baking the same. CONSTITUTION:Water is added to an activated alumina powder to adjust the moisture of said powder to 25-35wt.%. Subsequently, the alumina powder adjusted in its moisture content is molded under pressure of 100kg/cm to obtain molded which is, in turn, aged at 60 deg.C higher in a hermetically closed state and subsequently dried and baked to obtain alumina carrier having a pore size of 10 Angstrom or more enhanced in mechanical strength. When the alumina carrier having further high mechanical strength is desired, the obtained alumina carrier may be impregnated with an aqueous alumina salt solution to be dried and baked. As the activated alumina powder, gamma-alumina, eta-alumina, rho-alumina, chi-alumina and theta-alumina can be used but rho-alumina and chi-alumina are pref. from the aspect of the strength of an obtained carrier.

Treatment of wastewaters from ore flotation containing aliphatic amines and hydrofluoric acid

Abstract: Wastewaters from feldspar flotation containing hydrofluoric acid and amines were effectively purified by neutralization‐clarification with a 10% solution of lime and polyelectrolytes, followed by a coke filtration and/or a Zeolite or Activated Alumina adsorption. A Polish synthetic Ca‐type Zeolite proved to be efficient in the elimination of fluoride ions at the pH of 7.8. At this pH the Zeolite was more efficient than the Activated Alumina N. Wastewaters from feldspar washing were effectively treated by coagulation with A12(SO4)3, yielding final effluents with the characteristics very close to the clarified postilotation wastewaters. After clarification amines and fluoride ions could be removed from feldspar postflotation and feldspar washing effluents mixed together. A final concentration of fluorides and amines in the purified wastewaters was below 2 mg/1.

Removing radium from water by plain and treated activated alumina. Project summary

Abstract: The research determined the feasibility of using BaSO4 -impregnated activated alumina and plain activated alumina for radium removal from ground-water by fixed-bed adsorption. The major factors influencing radium adsorption onto the two types of alumina were identified. The radium regenerability of the aluminas was also studied.

Production of nucleus-substituted chlorinated toluene

Abstract: PURPOSE:To produce the subject compound useful as raw materials for medicines and agricultural chemicals by an extremely simple post-treatment operation in a high yield by chlorinating toluene or monochlorotoluene in liquid phase in the presence of activated alumina as a catalyst. CONSTITUTION:Toluene(TOL) or monochlorotoluene(MCT) is chlorinated in liquid phase in the presence of activated alumina to produce the subject compound. The activated alumina is a quasi-stable alumina excluding alpha-alumina, generally exemplified by gamma-,delta-,eta-,theta-,kappa-,rho or chi-alumina. The feed ratio of chlorine to the reaction system is 0.01 to 0.1mol/g-cat.hr. The feed amount of TOL or MCT is preferably 0.05-1mol per 1.0g of the activated alumina for batchwise system, and 0.01-0.1mol/g-cat.hr for continuous system. In the process the production of highly nucleus-substituted chlorinated product is minimized, and the post-treatment is simplified.

Heat and mass transfer

Abstract: In a chemisorption reaction process wherein a polar gas is repeatedly alternately adsorbed and desorbed on a complex compound formed by adsorbing said polar gas on a metal salt, said complex compound capable of having a first density if allowed to expand without restriction during said adsorption, a method of increasing the reaction rates of said chemisorption reaction process comprises controlling the volumeric expansion of said complex compound formed during at least the initial adsorption reaction of said polar gas on said metal salt to form at least a partially structurally immobilized, self-supporting, coherent, reaction product mass having a second density. The metal salt may also be mixed with a zeolite, activated carbon, activated alumina or silica gel prior to the first adsorption reaction. In another embodiment, the polar gas is used initially to form a complex compound with the salt and thereafter desorbed and a nonpolar gas used for being adsorbed and desorbed on the zeolite, activated carbon, activated alumina silica gel, or metal hydride.

Ceria-Alumina Oxidation Catalyst and Method of Use

Abstract: The oxidation catalyst composition of the present invention a surface area of about 10 m 2 / g or more of ceria and alumina, for example, a weight ratio of about 1.5, respectively: comprises a catalytic material containing ceria and activated alumina of from 1.5: 1 to 1. Optionally, in the catalyst material, it is sufficient There promotes the oxidation of gas phase HC and CO, and SO 2 can contain a limited amount of platinum that is not oxidized excessively to SO 3. Further, in the catalyst material, the palladium may be included in any amount. The catalyst composition of the present invention have a utility as oxidation catalysts for pollution reduction of exhaust gases containing incompletely burned fuel or oil. For example, it can be used in the method of processing a diesel engine exhaust gas by contacting a hot diesel exhaust gas and the catalyst composition to promote the oxidation of the volatile organic fraction component of particulates in the exhaust gas.