Showing papers on "Activated alumina published in 1986"

Adsorption characteristics of fluoride onto hydrous alumina

Abstract: Fluoride removal by activated alumina, Type F‐1, depends primarily on the pH and surface loading. The optimal pH for fluoride removal is approximately 5. However, at pH<6.0, the aluminum (III) dissolved from activated alumina reacts with fluoride ions and forms alumino‐fluoro complexes. These complexes are unstable in neutral or alkaline pH regions. Consequently, the role of pH in minimizing alumina dissolution as opposed to maximizing fluoride removal must be considered. An alkalimetric titration method was used to determine the surface acidity of the activated alumina. The intrinsic constants, pKa1int and pKa2int, are 4.2 and 10.5, respectively, in 0.05 M NaClO4, and the density of Bronsted acid sites is approximately 5.6×1013/cm2. A surface complex formation model was used to describe the removal of fluoride by activated alumina. These reaction mechanisms can be identified as a surface complex formation involving Al¯OH and Al¯OH2+. Polynuclear surface complex may be formed at high surface loading.

Catalyst compositions and methods of making the same

Abstract: A method of making a catalyst composition comprising an activated alumina coating stabilized against thermal degradation includes applying a coating of alumina having one or more platinum group metal catalytic components dispersed thereon onto a carrier substrate and calcining the coating. The calcined coating is then impregnated with a solution of a thermal stabilizer-precursor and calcined again to provide a thermal stabilizer in the alumina. Bulk ceria, optionally an aluminum-stabilized bulk ceria, may also be added to the composition, preferably at specified minimum levels, including a high purity bulk ceria on which one or more non-rhodium platinum group metal catalytic components, e.g., platinum, optionally, are dispersed. A separate aspect of the invention provides for a method of making a catalyst composition including dispersing one or more platinum group metal catalytic components on an activated alumina and calcining the combined alumina and platinum group metal catalytic components. The steps are carried out under limited acidification conditions whereby at least minimum dispersions of the platinum group metal catalytic components are attained. The invention also provides for catalyst compositions resulting from either or both the foregoing methods.

Catalyst for purifying 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 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.

Activated carbon/alumina composite

Abstract: Disclosed is a method of preparing an activated carbon/alumina composite. The method includes providing a blend containing activated alumina powder and activated carbon powder. Added to the blend is an aqueous solution to form a mixture. A green body is then formed from the mixture and heated to form the activated carbon/alumina composite.

Process for removal, separation and recovery of heavy metal ions from solutions using activated alumina including acid treated activated alumina

Abstract: An improved process is disclosed for the purification of an impure aqueous solution containing heavy metal ions which comprises passing the impure solution through a bed of activated alumina adsorbent. The heavy metal ions are removed from the impure aqueous solution by adsorption onto the activated alumina adsorbent. The adsorbent may be regenerated for reuse and the adsorbed metals recovered by subsequently stripping the metal ions from the adsorbent and recycling the metal ions back to the process of origin. The pH of the effluent may be monitored to determine when the capacity of the adsorbent has been reached and regeneration of the adsorbent should be commenced. In a preferred embodiment, a portion of the activated alumina is pretreated with acid before passing the impure solution through the adsorbent to enhance the chromium ion adsorption of the acid-treated activated alumina and a portion of the regenerated activated alumina is again treated with acid after each regeneration cycle.

Composite adsorbent for removing acids from organophosphate functional fluids

Abstract: A composite adsorbent useful for reducing the acidity and moisture content of used organophosphate functional fluids. The adsorbent is a powder having an average particle size of about 20-500 microns and total pore volume of at least about 0.40 cm 3 /g and it comprises about 40-90 wt % alumina and about 10-60 wt % Y zeolite wherein the molar ratio of SiO 2 to Al 2 O 3 is about 4.5-6.0. The adsorbent is preferably produced by agglomerating particles of activated alumina and Y zeolite into a composite agglomerate, aging the agglomerate and then comminuting to form a powder.

Process for removing nitrogen oxides and sulfur oxides from a waste gas

Abstract: 1. A process of removing nitrogen oxides (NOx ) and sulfur oxides from an exhaust gas which contains nitrogen and water vapor and which at temperatures of 40 to 120 degrees C is contacted with activated alumina and activated carbon as catalysts, wherein the alumina mainly combines with the nitrogen oxides, the activated carbon removes the sulfur oxides and combines with them to form sulfuric acid, and a reducing gas is used to regenerate the laden catalysts, characterized in that the exhaust gas is first conducted over activated alumina to substantially remove the nitrogen oxides and to remove a part of the sulfur oxides at the same time, the partly purified exhaust gas, which contains oxygen and water vapor, is subsequently conducted over the actived carbon, the laden alumina is regenerated in an AL2 O3 regenerator and separately thereform the laden activated carbon is regenerated in an activated carbon regenerator, the activated carbon regenerator is supplied with hydrogen-containing reducing gas, the sulfur and the sulfur-containing compounds are removed from the activated carbon at a maximum temperature of 400 to 550 degrees C, a reducing gas which contains sulfur compounds is withdrawn from the activated carbon regenerator and is fed to the Al2 O3 regenerator, the reducing gas which contains sulfur compounds is used at maximum temperatures of 200 to 400 degrees C to reduce the loading of the alumina to form sulfur and nitrogen and to desorb the loading, and a sulfur-containing desorption gas is discharged.

Removal and recovery of silver from waste stream

Abstract: In accordance with the invention, an improved process is provided for the efficient removal and recovery of silver from an impure solution containing silver ions which comprises contacting the silver-containing solution with an activated alumina adsorbent to selectively adsorb the silver ions from the solution and the lower the subsequent effluent discharge to less than 1 ppm silver, treating the activated alumina with a regeneration fluid to recover the silver ions from the adsorbent, and reducing the recovered silver ions to metallic silver.

Catalyst for purifying carbon monoxide and gaseous hydrocarbon in diesel exhaust gas

Abstract: PURPOSE:To enhance the purification capacity of CO, by containing at least one component selected from metal V and a V-compound and one or more of a metal selected from Pt, Pd and Rh and/or a compound thereof as catalytically active substances CONSTITUTION:A porous inorg substance is supported by a honeycomb shaped monolithic carrier in a slurry form according to a coating method and this supported layer is immersed in a solution containing a compound of a platinum group metal selected from platinum, palladium and rhodium to support said compound before drying and a solution containing a vanadium compound to support said vanadium compound while the impregnated carrier is dried and baked to obtain a catalyst for purifying carbon monoxide and gaseous hydrocarbon in diesel exhaust gas As the material of the honeycomb shaped monolithic carrier, cordierite, mulite, alumina and a heat resistant metal are generally used As the porous inorg substance, activated alumina, silica or titania are pref

Mode D'elimination de composes organiques polaires par une alumine activee γ‐Al2O3 en milieu aqueux. Comparaison avec le charbon actif.

Abstract: Batch experiments carried out on dilute solutions of organic acids (oxalic, maleic, benzoic and salicylic acids, humic substances) showed that activated alumina γ‐Al2O3 removed these solutes from water. The removal of organic acids was optimum in an acid medium (4 < pH < 6) and was significantly affected by the presence of inorganic anions. Filtration experiments showed competitive fixation of organic acids on γ‐Al2O3. Activated alumina could be regenerated by sodium hydroxide solutions but an important loss of efficiency of the filters was observed for the salicylic acid removal during 5 exhaustion‐regeneration cycles. A comparative study showed clearly that granular activated carbon (F400) had higher adsorptive capacities and was a better support for bacterial growth than activated alumina y‐A12O3.

Preparation of catalyst for purifying exhaust gas

Abstract: PURPOSE:To enhance the capacity of an exhaust gas purification catalyst, by supporting a compound of a catalytic metal selected from platinum group elements by an integral structure coated with a porous film containing activated alumina and baking the supported structure in an oxygen-containing atmosphere. CONSTITUTION:At least one or more of a catalytic metal selected from platinum group elements is supported by an integral base structure coated with a porous film containing activated alumina. Subsequently, the aforementioned carrier is baked at 400-700 deg.C in a state contacted with an atmosphere containing oxygen in an amount 0.9-1.4 times that of oxygen necessary for perfect combustion, that is, an atmosphere wherein the concn. of oxygen (O2) in combustion gas was regulated to a range of lambda=0.9-1.4 calculated according to formula to obtain an exhaust gas purification catalyst. By this method, the content of the harmful component such as chlorine remaining in the catalyst can be reduced and th enhancement of catalytic capacity is enabled.

Removal of impurities from n-methyl-pyrrolidone using highly pure water washed activated alumina

Abstract: N-methyl pyrrolidone solvent (hereinafter NMP) used to extract aromatic components from lubricating oil distillates is purified by contacting the solvent with activated alumina.

Preparation of catalyst structure

Abstract: PURPOSE:To uniformize pore distribution and to enhance purifying capacity, by coating the surface of a carrier with an aqueous catalyst slurry to which a combustible substance and a combustible org. solvent were added and removing the excessive aqueous catalyst slurry before baking. CONSTITUTION:A combustible substance 2 such as powdery activated carbon, a combustible org. solvent 3 such as light oil and a surfactant 4 are added under stirring to an aqueous catalyst slurry 1 prepared by mixing activated alumina with water to which a small amount of nitric acid was added. The obtained aqueous catalyst slurry 1 is applied to the surface of a ceramic carrier 5 according to a wash-coating method to form a wash-coat layer 6 and air blow is subsequently applied to the wash-coat layer on the surface of the carrier 5 to remove the excessive aqueous catalyst slurry. Thereafter, baking is performed to burn off the combustible substance 2 and the combustible org. solvent 3 to obtain a catalyst structure wherein pores 7 are formed to the surface of the layer 6.

Preparation of monolithic type exhaust gas purifying catalyst

Abstract: PURPOSE:To enhance the purifying action of a ternary catalyst, by forming the platinum group element fixed to activated alumina into an aqueous slurry along with a cerium hydroxide powder and applying said aqueous slurry to a monolithic carrier before additionally applying the other component. CONSTITUTION:At least one of compounds of platinum group elements are supported by an activated alumina powder in a dispersed state to fix at least one of platinum group metals onto activated alumina. This supported platinum group element composition is formed into an aqueous slurry along with a cerium hydroxide powder to prepare a slurry composition which is, in turn, applied to a monolithic carrier. On the other hand, a rhodium compound is supported by an activated alumina powder in a dispersed state to fix rhodium onto activated alumina while the obtained composition is formed into an aqueous slurry which is, in turn, additionally applied to the monolithic carrier, to which the aforementioned coating treatment was applied, to form an exhaust gas purifying catalyst.

Catalyst carrier for purifying exhaust gas

Abstract: PURPOSE: To enhance the high-temp. durability of a catalyst by incorporating α-alumina and θ-alumina in the coating layer on the upstream side of a base material, and incorporating α-alumina and γ-alumina in the coating layer on the downstream side. CONSTITUTION: When a coating layer of activated alumina is laminated on the honeycomb monolithic base material, α-alumina and θ-alumina are incorporated in the coating layer of activated alumina on the upstream side in the flowing direction of exhaust gas. Furthermore, δ-alumina and γ-alumina are incorporated in the coating layer of activated alumina on the downstream side, and the catalyst carrier for purifying exhaust gas is formed. Cordierite, mullite, etc., are used as the honeycomb monolithic base material, and triangular, square, and corrugated cell structures are appropriately used. Platinum, palladium, and rhodium are appropriately used as the metals to be deposited on the catalyst carrier. COPYRIGHT: (C)1987,JPO&Japio

Manufacture of integral structure type catalyst for purifying waste gas

Abstract: PURPOSE:To increase the gas purifying degree and durability of the titled catalyst by mixing activated alumina having specified narrow pore diameter with alumina sol, crushing the mixture to make slurry and forming an aluminum oxide coating on the surface of a catalyst. CONSTITUTION:Activated alumina contg. cerium preliminarily wherein >=80% all narrow pore volume is occupied by the narrow pore volume of 200-600Angstrom narrow pore diameter is mixed with cerium oxide and alumina sol and the mixture is crushed and the obtained slurry is impregnated into an integral structure type carrier, dried and calcined and thereafter the essential catalytic metals are deposited on the composite oxide coating formed on the carrier. Separately, after the slurry of mixed and crushed material of both alumina wherein >=80% all narrow pore volume is occupied by the narrow pore volume of 200-600Angstrom narrow pore diameter and alumina sol is coated on the carrier deposited with the above-mentioned essential catalytic metals, it is dried, calcined to manufacture the waste gas purifying catalyst for removing carbon monoxide, hydrocarbons and nitrogen oxides contained in the waste gas.

Preparation of catalyst carrier

Abstract: PURPOSE:To obtain a catalyst carrier excellent in durability, by adhering a slurry comprising an acidic aqueous solution containing specific activated alumina and a specific metal salt to a monolithic carrier and subsequently forming a film comprising a specific wt. ratio of activated alumina and metal oxide by backing. CONSTITUTION:An activated alumina powder having an average particle size of 20mum or less and pref. having a specific surface area of 75m /g or less is mixed with an acidic aqueous solution containing at least one metal salt selected from a rare earth metal salt, a cobalt salt and a zirconium salt to obtain a slurry of which the pH is pref. 3-5.5 and the solid component is pref. 50wt% or more. Subsequently, said slurry is adhered to a monolithic carrier while the treated carrier is dried and subsequently backed pref. at 250-800 deg.C. By this method, a catalyst carrier having a film consisting of 1-50wt% of metal oxide and 50-90wt% of activated alumina formed thereto is obtained.

Hydrocracking of liquefied coal

Abstract: PURPOSE:To provide a method of hydrocracking liquefied coal which enables the hydrocracking to be continuously conducted for a long period of time with excellent catalytic activity and selectivity while suppressing the deposition of a carbonaceous substance on a catalyst, by conducting the hydrocracking of liquefied coal in the presence of a specific hydrocracking catalyst. CONSTITUTION:An activated alumina powder such as gamma-alumina or an activated alumina precursor powder such as a hydrated alumina powder, e.g. boehmite powder is mixed with water and a forming assistant (e.g. nitric acid or a basic nitrogen compound) and, if necessary, 10-120wt% of carbon black. The mixture is formed into a spherical shape having a diameter of 0.5-3mm or a cylindrical shape having a diameter of 0.5-3mm and dried. The product is calcined at 500-1,000 deg.C for 1hr to 1 day to obtain a (porous) activated alumina to be used as a supporting material. On the activated alumina are supported 1-50% (by weight in terms of oxide; the same applies hereinafter) of a metal belonging to Group VI A of the periodic table and 0.1-20% of Ni or Co, or 0.01-10% (in terms of metal) of a platinum group metal etc. to obtain a hydrocracking catalyst. A liquefied coal which has been obtained as a secondary hydrocracking reaction product of a two-stage hydrocracking reaction of coal is decomposed to make more volatile in the presence of the hydrocracking catalyst under an H2 pressure of 50-300kg/cm G at a temperature of 250-500 deg.C and a liquid space velocity of 0.1-5hr .

Catalyst for treating exhaust gas of car

Abstract: PURPOSE:To remove simultaneously three components of NOx, HC and CO in the high efficiency by providing a catalytic layer which contains activated alumina contg. ceria, ceria, praseodymium oxide and catalytic active metal on the surface of a monolithic base material. CONSTITUTION:In a catalyst for purifying the exhaust gas discharged from an internal combustion engine of a vehicle especially a car, a catalytic layer 3 consisting of alumina contg. ceria, ceria, praseodymium oxide and catalytic active metal such as Pt and Rh is formed on the surface of a monolithic base material, namely a base material 2 molded in one body. In the catalyst obtained by such a way, three components of NOx, HC and CO can be simultaneously removed in the high efficiency and also it has the high heat resistance and the resistance to lead and the purifying performance is stabilized and enhanced.

Production of hydrogenation catalyst

Abstract: PURPOSE: To improve hydrogenation activity and its durability by depositing at least one kind of activated metal for hydrogeneation selected from among group VIB metals and group VIII metals of the periodic table on a porous activated alumina carrier. CONSTITUTION: After preparing a mixture contg. both the powder of activated alumina or a precursor of activated alumina and carbonaceous fiber and drying it, it is calcined in an air current contg. oxygen to calcine and remove carbonaceous fiber and thereby a porous activated alumina carrier is formed. A hydrogenation catalyst is produced by depositing at least one kind of activated metal for hydrogenation selected from among group VIB metals and group VII metals of the periodic table on the alumina carrier. As the other method, after drying a mixture contg. activated alumina, carbonaceous fiber and one kind of activated metal for hydrogenation selected from among group VIB metals and group VIII metals of the periodic table, the hydrogenation catalyst can be produced by calcining it in the air current contg. oxygen. COPYRIGHT: (C)1987,JPO&Japio

Production of catalyst for purifying exhaust gas

Abstract: PURPOSE:To form a film having a high covering strength by covering a carrier with a specified solid quantity of an alumina slurry composed of activated alumina powder having <=15mum average particle diameter and ammonium salts of polyacrylic acid oligomer. CONSTITUTION:The alumina slurry which is composed of activated alumina powder having <=15mum average particle diameter and ammonium salts of polyacrylic acid and whose solid matter content is 50-90wt% is prepared. By using said slurry an activated alumina film is formed on a monobloc structure carrier made from cordierite and further a catalytic metal is supported on said carrier on which said film is formed, thus the catalyst for purifying the exhaust gas is formed. The temp. at which the alumina slurry stuck onto the carrier is calcined is preferably to be 250-1,000 deg.C. Noble metals such as platinum, palladium, rhodium, etc., are used as a catalytic metal.

Oxidation of ammonia over a mixed catalyst bed of cobalt and aluminum oxides

Abstract: This invention is a catalyst and method of oxidizing ammonia by contacting the ammonia and air with catalyst of cobalt oxide, wherein the improvement comprises using activated alumina in conjunction with the cobalt oxide catalyst.

Process for removing carbonyl sulphide from liquid propylene

Abstract: There is disclosed a process for removing COS from liquid propylene feedstreams containing relatively high quantities of water by hydrolysis of the feedstream using activated alumina as the catalyst, the catalyst being periodically regenerated, and passing the feedstream through one or more secondary reactors whereby a liquid propylene containing 50 wppb or less COS is obtained.

Combustion chamber of internal-combustion engine

Abstract: PURPOSE:To improve adhesion of an alumina coat layer with catalyst by using slurry, obtained through mixed pulverization of boehmite alumina-sol with alumina carrying noble metals attached thereto and later maturing it with added acid, in a combustion chamber which has said layer CONSTITUTION:An alumina coat layer 9 with catalyst is formed on a piston 4, cylinder head 3 and a vortex chamber 2 in the main chamber 1 of a combustion chamber The alumina coat layer 9 with catalyst is formed through drying and baking a flame spraying layer, which has ZrO2 as its main ingredient, after attaching slurry thereto Further, this slurry is made through mixed pulverization of boehmite alumina-sol, which is stabilized with nitric acid, with activated alumina which previously bears catalyst of noble metals and is baked, and later maturing by adding acid Thus, a part of activated alumina and noble metals is melted again and adhesion of the alumina coat layer is improved

Separation of carbon monoxide

Abstract: PURPOSE:To save the initial cost and the operation energy for the separation of carbon monoxide from a mixed gas, by using an adsorbent composed of activated alumina impregnated with cuprous chloride and aluminum chloride. CONSTITUTION:An activated alumina carrier having the shape of sphere, honeycomb, plate, pipe, etc. is prepared beforehand. The carrier is impregnated with a solution obtained by dissolving cuprous chloride and aluminum chloride in a solvent, and the solvent is evaporated to obtain a solid carrier for the separation of carbon monoxide gas from a mixed gas containing the same.

Method and apparatus for reducing chemical oxygen demand in water

Abstract: A method and apparatus for reducing chemical oxygen demand levels in water which includes the steps of: (a) mixing the water to be treated with at least one oxygen source; (b) contacting the water with a first, activated alumina catalyst; (c) contacting the water with a catalyst selected from the group consisting of Group VIIIB metals, Group IB metals or mixtures thereof; (d) reacting chemical contaminants in the water with the oxygen source; and finally (e) contacting the water with an adsorptive material such as activated carbon. The present invention also includes a method and apparatus for regenerating the catalyst in situ by contacting the catalyst with alkaline and acidic aqueous inorganic regeneration solutions.

Preparation of monolithic catalyst carrier for purifying exhaust gas

Abstract: PURPOSE:To prevent the peeling off of activated alumina from a carrier base material by depositing specified substances such as Ca and Sr on the surface of the carrier base material made of Cr-Fe-Al ferrite stainless steel, heat- treating the material, and then forming a catalyst carrying layer consisting of activated alumina. CONSTITUTION:The corrugated sheet 2 and flat sheet 3 of a metallic thin sheet are alternately wound to form the metallic carrier base material. One or more kinds among Ca, Sr, Ba, Ra, K, Rb, Cr, and Fr are deposited on the material and heat-treated to form an oxide coated film 4 consisting essentially of activated alumina. In this case, the ionic radii of Ca, etc., are larger than the ionic radius of an Al ion, the crystal structure of activated alumina is stabilized, and the transition to alpha-alumina is controlled. A slurry contg. activated alumina is deposited, and the catalyst carrying layer 5 consisting essentially of activated alumina is formed on the oxide coated film. Consequently, the bond strength between the activated alumina layer and the metallic carrier base material is improved, and the stripping off of the activated alumina is prevented.