Showing papers on "Selective catalytic reduction published in 1981"

Process for efficiently removing oxides of nitrogen from exhaust gas

Abstract: A system for removal of oxides of nitrogen from the waste gas produced by various combustion processes discloses thoroughly mixing the waste gas with ammonia by means of a static mixing element and then passing the resultant mixture through a catalytic reactor. The ammonia may be supplied by reacting a portion of the waste gas with natural gas in the presence of a catalyst.

Process for the removal of urea, ammonia, and carbon dioxide from dilute aqueous solutions

Abstract: An improved process for the removal of urea, ammonia, and carbon dioxide from dilute aqueous solutions thereof by hydrolyzing the urea, and thereafter desorbing ammonia and carbon dioxide. The dilute solution containing urea is passed into the top portion of a reaction column and caused to flow downward and countercurrent to a heating and stripping gas while maintaining the reaction column at a pressure of between about 10 and 30 bar, and a top column temperature of between about 170° and 220° C. and a bottom column temperature of between about 180° and 230° C. The resulting liquid stream removed from the bottom of the reaction column, comprised of a substantially urea-free aqueous solution of ammonia and carbon dioxide, is introduced into a desorption zone wherein, at a pressure of between about 1 and 5 bar, ammonia and carbon dioxide are removed therefrom.

Method of cleaning gases from nitrogen oxides

Abstract: FIELD: cleaning waste flue gases of tubular furnaces used in power technological plants of ammonia production process from nitrogen oxides. ^ SUBSTANCE: proposed method includes mixing flue gases with air and ammonia-containing reductant. Used as ammonia-containing reductant are synthetic gases of ammonia production process of the following composition, mass-%: ammonia, 20-30; methane, 18-24; hydrogen, 25-35; argon, 3.8-4.8; the remainder being nitrogen. Selective catalytic reduction of nitrogen oxides of flue gases is performed in reactor at temperature of 240-450°C with the use of tungsten-vanadium catalyst. Proposed method makes it possible to clean flue gases to 91%. ^ EFFECT: high degree of cleaning. ^ 2 ex

Process of making L-gulono gamma lactone

Abstract: L-gulono gamma lactone is made in a one-step process by the simultaneous hydrolysis and catalytic reduction with hydrogen in acid medium of polyglucuronic acid or a lower alkyl glucuronoside. A use statement--L gulono gamma lactone can be converted chemically or biologically to L-ascorbic acid (vitamin C).

Treatment of waste gas

Abstract: PURPOSE:To remove nitrogen oxides stably at a relatively lower temperature while maintaining the activity of a catalyst by removing selectively sulfer trioxide from waste gas containing nitrogen oxides and sulfer oxides, and then catalytically reducing the waste gas with ammonia. CONSTITUTION:Sulfer trioxide is selectively removed at a temperature of from 200 to 350 deg.C from waste gas containing nitrogen oxides and sulfer oxides by using, as an absorbent, an alkali metal or alkaline earth metal oxide such as calcium oxide, etc. or iron oxide. Then, the resulting gas is reduced catalytically with ammonia at a temperature of from 200 to 350 deg.C. When sulfer trioxide is previously removed, subsequently the catalytic reduction of the waste gas with ammonia can be carried out at a relatively lower temperature, and the activity of the catalyst and the removal rate of nitrogen oxides can be maintained stably.

Process for preparing adenine

Abstract: A process for preparing adenine by reacting an arylazomalononitrile with formic acid or its derivatives in the presence of ammonia and then subjecting the intermediate pyrimidine derivative to a reaction under catalytic reduction condition. Adenine can be prepared in high purity and high yields without isolating the intermediate pyrimidine derivative, when ammonia is removed before conducting the reaction under catalytic reduction condition. Also, the preparation of adenine in high purity and high yields can be more surely attained, when the arylazomalononitrile prepared under a specific condition is employed as a starting material or when Raney nickel is employed as a reduction catalyst in combination with active carbon. The produced adenine is effectively purified by separation of insoluble materials from an aqueous hot solution of adenine adjusted to pH 7.5 to 9.0 and formation of a mineral acid salt of adenine followed by decoloration by heating in the presence of active carbon.

Production of ppaminomethylbenzoic acid or its derivative

Abstract: PURPOSE:4-Carboxybenzaldehyde, after oximated, is subjected to catalytic reduction in the presence of ammonia or an acylating agent to produce titled compound used as a monomer and starting material for medicine with industrial advantage. CONSTITUTION:After 4-carboxybenzaldehyde or its alkyl ester is oximated with hydroxylamine, the catalytic reduction is effected in the presence of ammonia or an acylating agent and a catalyst of Ni or Pd to produce p-aminomethylbenzoic acid or its derivative. Raney nickel is preferred as the Ni catalyst. The acylating agent is preferably a mixture of acetic anhydride and acetic acid and in this case the use of 5%Pd-C catalyst is preferred. The process is high-safety because the use of hazardous p-cyanobenzoic acid can be avoided and shortened in steps, thus giving high-purity titled compound in high yield.

Preparation of cymene

Abstract: PURPOSE:To obtain cymene economically, by the catalytic reduction of dimethylstyrene with hydrogen in a specific temperature range passing the starting material together with hydrogen upwardly through a catalytic layer consisting of a Pd-aluminum catalyst. CONSTITUTION:Cymene is obtained by the catalytic reduction of dimethylstyrene with hydrogen at 10-130 deg.C in the presence of a Pd-alumina catalyst (the content of Pd in the catalyst is pref. 0.3-0.5wt%). the dimethylstyrene is passed together with hydrogen upwardly through the catalyst layer.

Process for removing nitrogen oxide gas

Abstract: In a process for reducing the NOx contents in waste gases, particularly waste gases from a nitric acid plant, by catalytic reduction of the NOx gases, a solution is to be provided, by means of which especially the nitrogen oxides content in waste gases can be reduced to the low values now demanded, without the catalyst used being irreversibly poisoned. This is achieved by carrying out the reduction in two stages, part of the NOx gas being dissolved out in a first stage by means of alkalis such as, for example, sodium hydroxide solution or sodium carbonate solution, and the remainder of NOx gas then being catalytically reduced to nitrogen in a second stage with addition of ammonia.

Preparation of 22chloroo55trifluoromethylpyridine

Abstract: PURPOSE:To obtain the titled compound in high yield in chlorinating and fluorinating beta-picoline in the presence of a fluoride of aluminum, etc. as a catalyst in an inert diluent in gas phase, by subjecting by-products to catalytic reduction in the presence of a platinum catalyst, followed by recycling the prepared beta-trifluoromethylpyridine through the above-mentioned reaction system. CONSTITUTION:In the presence of at least one catalyst selected from the group consisting of fluorides of aluminum, chromium, iron, and nickel and an inert diluent, beta-picoline is reacted with chlorine and anhydrous hydrogen fluoride in fluid state to give the titled compound and a mixture of chloro beta-trifluoromethylpyridines containing 2-chloro-3-trifluoromethylpyridine, etc. as by-products. The titled compound is separated from the mixture and collected. The residue solution is subjected to contact reaction with hydrogen in the presence of a catalyst of platinum, palladium, nickel, copper, or silver so that the above-mentioned by-products are converted into beta-trifluoromethylpyridine, which is recycled through the reaction system to utilize the by-products effectively and to give the titled compound in high yield.

Catalyst for removal of nitrogen oxides in exhaust gas

Abstract: PURPOSE:To obtain the catalyst for removal of nitrogen oxides, having a high activity less variable in the course of time, for a catalytic reduction by a method in which vanadium oxide and tungsten oxide are supported in a specific ratio on the surface of a titanium oxide carrier and then covered with cerium oxide. CONSTITUTION:A denitrification catalyst for a catalytic reduction is manufactured by a procedure in which 1:5-1:50 (by weight) active composition consisting of 2-25wt% vanadium oxide, and tungsten oxide is supported on a titanium oxide- based carrier and then covered with 0.5-2.5wt% cerium oxide. The catalyst thus obtained is excellent in catalytic activity and durability in a wide range of temperatures as well as in the convertibility of SO2 into SO3 with less variation with time.

Control device for amount of ammonia addition in denitration of coke oven waste gas

Abstract: PURPOSE: To remove NO x efficiently and economically and reduce unreacted ammonia by controlling the amount of ammonia addition according to the fluctuations in the NO x concn. in waste gas in a catalytic reduction denitration method for coke over waste gas. CONSTITUTION: In the catalytic reduction denitration of coke oven waste gas, the total amount of NO x s in the waste gas entering the catalyst bed of a reaction tower 1 is determined from flow rate and an analyzer 12, and the amount of ammonia corresponding to this is calculated with a rate setter 14. A control valve 24 is moved by the deviation between this signal and the actual flow rate of ammonia. Whereas, coke oven undergoes alteration periodically, and causes a sharp decrease particulrly in the NO x concn. and therefore at such a time, a timer 26 operates to cut off between a controller 23 and the valve 24, thereby stopping the supply of ammonia. In this way, denitration is accomplished efficiently, and even more, the oversupply of ammonia is eliminated and secondary pollution is prevented. COPYRIGHT: (C)1981,JPO&Japio

Catalyst for removing nitrogen oxide and its production

Abstract: PURPOSE:To reduce the deposition of ammonium sulfate or the like on a catalyst surface and improve activity at low temp. by contg. titanium oxide, oxide of metals such as vanadium and inorg. fibrous materials as a catalyst for removing nitrogen oxide. CONSTITUTION:At least one kind out of titanium oxide and oxide of metals such as tungsten, vanadium and other as well as inorg. fibrous materials of silica, inorg. glass, etc. are contained as a catalyst used for catalytic reduction of NOx in waste gas contg. SOx by NH3. When these are molded and fired after kneading, fine pores of large diameters disperse uniformly in a large amount in the catalyst, thereby preventing ammonium sulfate or acidic ammonium sulfate from depositing on the surface and improving catalyst activity at low temp.

1,1-diisopentylacetone

Abstract: NEW MATERIAL:1,1-Diisopentylacetone of formula I. USE:Useful as a perfume, a base for a cosmetic or a solvent. PROCESS:1,1-Diisopentenylacetone is hydrogenated to give the compound of formula I. The catalytic reduction is preferably carried out by using a palladium catalyst supported on carbon. The amount of the catalyst is preferably 0.1-10wt% based on the 1,1-diisopentenylacetone. The reaction solvent is an inert one such as a saturated hydrocarbon, ether or ester, and the reaction conditions are a hydrogen pressure of normal to 50kg/cm and ordinary temperature to 200 deg.C.

Nox controls: many new systems undergo trials

Abstract: New systems to control nitrogen oxides emissions in flue gases from coal-burning power plants are being tested. These systems would complement co in the combustion process, and the conventional techniques used to control NOx emissions are discussed. Problems and prospects of several flue gas control systems are explored. These systems generally involve selective catalytic reduction of NOx to nitrogen and water by injection of ammonia in the presence of a catalyst. Some experts feel that these added controls are unnecessary, and that combustion controls alone can meet increasingly stringent U.S. emission standards.

Preparation of longgchain aliphatic secondary amine

Abstract: PURPOSE:To prepare the colorless, high-purity titled compound in high yield, by the nitrilation and catalytic reduction of a product obtained by contacting a preliminary deaerated higher fatty acid with NH3-H2 mixed gas extracted from the following catalytic reduction process. CONSTITUTION:A fatty acid stored in the storage tank 8 is deaerated in a deaerating tower 9, and contacted in a packed column 7 with NH3-H2 mixed gas taken out from the catalytic reduction reactor 5 to obtain a mixture of a higher fatty acid and the ammonium salt of the higher fatty acid. The mixture is separated from H2 gas, and sent to the nitrilation reactor 1, in which it is reacted with NH3 supplied from the tank 2 to afford a nitrile. H2 gas supplied from a hydrogen bomb and the one separated from the packed column 7 and purified by removing NH3 in the washing column 10 and liquid impurities in the cyclone 11, is made to react with the nitrile in a catalytic reduction reactor 5 to afford the objective secondary amine, which is recovered from the bottom of the reactor 5.

Dry type sulfur recovering desulfurization method

Abstract: PURPOSE:To smooth reaction, by introducing part of concentrated SO2 gas directly into a catalytic reduction tower in order to control a mole ratio of H2S to SO2 in the process of conducting Claus reaction of a gas containing H2S and SO2 leaving an SO2 reduction tower, in the catalytic reduction tower. CONSTITUTION:Waste gas exhausted from boiler 1 is introduced to adsorber 2 to adsorb SO2 in the waste gas with an adsorbent, and the purified gas is exhausted from smokestack 5 to the open air. The adsorbent with SO2 adsorbed is fed to desorber 3, reactivated by heating, and returned to adsorber 2. On the other hand, concentrated SO2 gas obtained from desorption of SO2 is introduced to SO2 reduction tower 4, reduced with carbon supplied through pipe 32 to produce simple substance S, and this is recovered via condenser 8. The residual gas containing H2S and SO2 and leaving condenser 8 is sent to catalytic reduction tower 9, at the same time, part of the concentrated SO2 gas produced from desorber 3 is introduced through pipe 34 in order to control a mole ratio of H2S/SO2 to 2, thus permitting the Claus reaction to be efficiently carried out and simple substances S to be produced.

Refinery catalytically cuts NO/sub x/ emissions

Abstract: To meet nitrogen oxides emission standards, the USA Petrochem refinery in Ventura, Calif., had to install a selective catalytic reduction system. The thermodynamically designed system is described. The denitrification process employed mixes vaporized ammonia with the flue gases before passing through a catalyst bed reducing NOx to harmless nitrogen and water vapor. This reaction will occur at 1800chemically bond F without the presence of a catalyst, but the addition of the catalyst allows the reaction to take place at much lower temperatures.

Highly active catalyst for denitration of exhaust gas

Abstract: PURPOSE:To offer a catalyst which can maintain its high activity to sulfur oxide- containing exhaust gas for a long period, by further supporting wolfram oxide on a copper sulfate-carrying silica/alumina catalyst to be used in the catalytic reduction of nitrogen oxides by ammonia. CONSTITUTION:The catalyst comprises copper sulfate and wolfram oxide supported on an active silica/alumina carrier containing 40-90wt% silica. If the silica content is less than the lower limit, the deterioration of the catalyst is conspicuous in the disposal process of sulfur oxide-containing exhaust gas. If the silica content exceeds the upper limit, the activity, especially the initial activity, of the catalyst is insufficient. The wolfram oxide has an effect of further enhancing the catalytic activity of the copper compound. The amount of wolfram oxide is 0.12-0.22g/1g-carrier.

Inert gas generation utilizing diesel exhaust

Abstract: The generation of inert gas from 60 KW diesel engine exhaust by catalytic reduction of O{sub 2} and NO{sub x} has been demonstrated. Measured O{sub 2} levels were < 10 V{sub ppm} and NO{sub x} levels were {approx} 0.1 V{sub ppm} over a wide range of equivalence ratios. Durability of the catalytic converter was demonstrated up to 200 hours operating time at two diesel engine load conditions. Effective catalyst operating range was stoichiometric to rich fuel/air ratios. Optimum operation is at stoichiometric fuel/air ratios to minimize CO emissions. Alternative converter designs are proposed to allow operation over the full diesel engine load range with essentially zero emissions of O{sub 2}, NO{sub x} and CO.

Production of 3*33diaminodiphenyl sulfone

Abstract: PURPOSE:To catalytic reduction of 3,3'-dinitrodiphenyl sulfone is carried out in the coexistence of a specific alkali metal compound and a reduction catalyst containing Pd or Pt to produce the titled compound used as a starting material for producing high-molecular-weight compounds in high purity and yield. CONSTITUTION:The catalytic reduction of 3,3'-dinitrodiphenyl sulfone with molecular hydrogen is carried out in a solvent such as 1-8C aliphatic alcohol or cyclohexanol in the presence of a catalyst containing Pd to produce the titled compound wherein at least one selected from hydroxides, oxides, carbonates and bicarbonates of alkali or alkaline earth metals is added to the reaction system to prevent the deactivation of the catalyst, resulting in high yield of the objective compound. The amount of the alkali metal compound employed is 0.1-5wt% on the basis of 3,3'- dinitrodiphenyl sulfone.

Catalytic Reduction of Nitric Oxide by Ammonia on Cobalt-Amine Complexes in Y-Zeolite and in the Solution

Abstract: Catalytic reduction of nitric oxide by ammonia proceeds over Co-amine complexes in Y-zeolite with the same mechanism as that in the solution, indicating a solvent-like function of zeolite.