Showing papers on "Selective catalytic reduction published in 1977"
TL;DR: In this article, the reduction of nitric oxide with ammonia was studied over transition metal ion exchanged Y zeolites (MeY), where one of the component ions was fixed as Cu(II), promoting effects of the second ionic species.
49 citations
Patent•
25 Jan 1977
TL;DR: In this article, the reduction of nitrogen oxides to nitrogen by passing the flue gas over a catalyst of metal compounds containing oxysulfur compounds in the presence of an ammonia gas is described.
Abstract: Nitrogen oxides are removed from flue gas evolving from stationary sources and containing the nitrogen oxides through reduction of nitrogen oxides to nitrogen by passing the flue gas over a catalyst of metal compounds containing oxysulfur compounds in the presence of an ammonia gas
30 citations
Patent•
09 Dec 1977TL;DR: In this article, a hot gas containing nitrogen oxides is mixed with ammonia and hydrogen peroxide to reduce the nitrogen oxide to nitrogen and water, and the reduction reaction of the nitrogen oxide by ammonia is considerably promoted in a temperature range of 400° to 800° C.
Abstract: A hot gas containing nitrogen oxides is admixed with ammonia and hydrogen peroxide to reduce the nitrogen oxides to nitrogen and water. Reduction reaction of the nitrogen oxides by ammonia is considerably promoted in a temperature range of 400° to 800° C. by the addition of hydrogen peroxide, and also ammonia present in excess of the nitrogen oxides is decomposed thereby, eliminating an unreacted ammonia effluent.
28 citations
Patent•
28 Mar 1977TL;DR: In this article, a process for treating an exhaust gas containing nitrogen oxides, oxygen and ammonia gas with a catalyst consisting essentially of titanium oxide, copper oxide, molybdenum oxide or tungsten oxide in an amount of 0.01 to 0.5 mole per one mole of the titanium oxide was described.
Abstract: A process for treating an exhaust gas containing nitrogen oxides, oxygen and ammonia gas with a catalyst consisting essentially of titanium oxide, copper oxide in an amount of 0.02 to 0.3 mole and molybdenum oxide or tungsten oxide in an amount of 0.01 to 0.5 mole per one mole of the titanium oxide. Because the catalyst exhibits good properties for decomposition of ammonia as well as for decomposition of nitrogen oxides it is possible to avoid secondary pollution due to unreacted ammonia.
18 citations
Patent•
21 Nov 1977TL;DR: In this article, ammonium sulfates are removed continuously or intermittently from a catalyst bed and fed to a regeneration tower where it is treated with a hot gas having a temperature of 350 ˜ 600° C.
Abstract: Ammonia is added to combustion flue gas containing nitrogen and sulfur oxides and the gas is brought into contact with a catalyst which contains titanium or tin oxide, or a mixture of the two, as a main component at a temperature between 150 ˜ 330° C. Nitrogen oxides are reduced to nitrogen and water, and sulfur oxides are deposited as ammonium sulfates, on the surface of the catalyst which causes a decrease in the ability of the catalyst. A part of the catalyst is removed continuously or intermittently from a catalyst bed and fed to a regeneration tower where it is treated with a hot gas having a temperature of 350 ˜ 600° C. The ammonium sulfates deposited on the catalyst are decomposed into SO3 and NH3. The SO3 is adsorbed by an SO3 absorbent and the NH3 is returned to the combustion flue gas to be treated.
16 citations
Patent•
17 Oct 1977TL;DR: In this article, the first transition metals of the periodic table were selected from a group of transition metals for catalytic reduction of nitrogen oxides with ammonia at a temperature of from 250° to 550° C and offer high resistivity to the poisonous effect of sulfur oxides.
Abstract: The present invention relates to a catalyst comprising at least a metal salt of heteropoly-acid, which is composed of a sort of heteropoly-acid and one or more metals selected from a group of the first transition metals of the periodic table The catalyst of the present invention exhibits high activity and selectivity in the catalytic reduction of nitrogen oxides with ammonia at a temperature of from 250° to 550° C and offers high resistivity to the poisonous effect of sulfur oxides It does not entail a wasteful use of the reducing agent, because the catalyst of the present invention does not accelerate the reaction of the reducing agent such as ammonia with oxygen coexisting in the waste gas to be treated, which results in the elimination of the undesired excessive consumption of the reducing agent Therefore, this invented catalyst may provide a commercially advantageous process for removing harmful constituents, nitrogen oxides from a waste gas which contains the same and additionally, in some cases, sulfur dioxides
14 citations
Patent•
14 Mar 1977
TL;DR: In this article, a process for the removal of nitrogen oxides from a waste gas containing said nitrogen oxide in conjunction with sulfur oxides is disclosed, which process comprises allowing said waste gas to come into contact with ammonia as the reducing agent at temperature in the range of from 250° to 550° C in the presence of a catalyst wherein an active component containing iron or copper as the active metal is supported on a silica-alumina type carrier.
Abstract: A process for the removal of nitrogen oxides from a waste gas containing said nitrogen oxides in conjunction with sulfur oxides is disclosed, which process comprises allowing said waste gas to come into contact with ammonia as the reducing agent at temperature in the range of from 250° to 550° C in the presence of a catalyst wherein an active component containing iron or copper as the active metal is supported on a silica-alumina type carrier containing not less than 60% by weight of silica and the pore volume occupied by the pores measuring 150 A or over in diameter exceeds 0.15 cc/g, for thereby causing selective catalytic reduction of said nitrogen oxides.
13 citations
Patent•
30 Dec 1977
TL;DR: In this article, a method for removing nitrogen oxides from a nitrogen oxide-containing gas by contacting the gas with ammonia excited by ultraviolet irradiation in the presence of a catalyst to react the nitrogen oxide with the ammonia is described.
Abstract: There is disclosed a method for removing nitrogen oxides from a nitrogen oxide-containing gas by contacting the gas with ammonia excited by ultraviolet irradiation in the presence of a catalyst to react the nitrogen oxides with the ammonia According to the method, the reaction of nitrogen oxides with ammonia proceeds more rapidly than in the case of prior art methods
12 citations
Patent•
10 Jun 1977TL;DR: In this paper, a compressed exhaust gas containing nitrogen oxides discharged from a compressed absorption type nitric acid plant is treated by adding ammonia or an ammonia precursor to the gas and passing the gas through a NOx removing catalytic layer to an exhaust gas turbine wherein the temperature of the main flow of the exhaust gas in the zone from the point of which ammonia or a precursor is added to the outlet of the turbine is maintained at a temperature higher than T° K = 103 / (1.91 - 0.228 log P) [P : a sum of partial pressures of
Abstract: A compressed exhaust gas containing nitrogen oxides discharged from a compressed absorption type nitric acid plant is treated by adding ammonia or an ammonia precursor to the gas and passing the gas through a NOx removing catalytic layer to an exhaust gas turbine wherein the temperature of the main flow of the exhaust gas in the zone from the point of which ammonia or an ammonia precursor is added to the outlet of the exhaust gas turbine is maintained at a temperature higher than T° K = 103 / (1.91 - 0.228 log P) [P : a sum of partial pressures of ammonia and nitrogen oxides (atm.)] and feeding an inert gas into the place of the zone in which the exhaust gas stagnates.
10 citations
Patent•
04 Jan 1977
TL;DR: In this article, the nitrogen oxides can be removed by contacting the exhaust gas with ammonia in the presence of a substance derived from laterite, which can be used to remove the nitrogen oxide from an exhaust gas.
Abstract: From an exhaust gas containing nitrogen oxides, the nitrogen oxides can be advantageously removed by contacting the exhaust gas with ammonia in the presence of a substance derived from laterite.
9 citations
TL;DR: In this article, an experimental study of the relative catalytic activities of rare earth oxides for reducing nitric oxide in the presence of carbon monoxide was reported, and the results showed that the most active rare earth oxide was cerium dioxide with activity being similar to that of platinum and palladium catalysts tested under similar conditions.
Patent•
29 Mar 1977
TL;DR: In this article, a solution of alkali at the spray tower of a spray tower was used to reduce NOx for a long period of time, by contacting the exhaust gas containing NOx, SOx, and O2 with minute drops of an alkali solution.
Abstract: PURPOSE:To carry out stably and economically the reduction of NOx for a long period of time, by contacting the exhaust gas containing NOx, SOx and O2 with minute drops of a solution of alkali at the spray tower, then treating the exhaust gas with the electric dust collector, thus decreasing the content of SOx in the exhaust gas below the specifiied amount and, after that, by reducing NOx by adding NH3 and passing through the catalyst layer for catalytic reduction
Patent•
08 Jul 1977
TL;DR: In this article, the title compound was obtained by catalytic reduction of xylylenediamine in the presence of a ruthenium catalyst, an alkali metal hydroxide, and 6 W 40 wt.% based on the weight of reaction system water.
Abstract: PURPOSE: To obtain the title compound useful as a raw material for polyamide in high yields in a short time, by catalytic reduction of xylylenediamine in the presence of a ruthenium catalyst, an alkali (earth) metal hydroxide, and 6 W 40 wt.% based on the weight of reaction system water. COPYRIGHT: (C)1979,JPO&Japio
Patent•
18 Jul 1977TL;DR: In this paper, a method for the removal of nitrogen oxides from heavy oil combustion exhaust gases containing nitrogen oxide, sulfur oxides and dusts by a catalytic reduction process using a moving catalyst bed reactor was proposed.
Abstract: A method for the removal of nitrogen oxides from heavy oil combustion exhaust gases containing nitrogen oxides, sulfur oxides and dusts by a catalytic reduction process using a moving catalyst bed reactor wherein the exhaust gases are catalytically contacted with ammonia at 250° to 450° C., which is characterized in that a sealing gas having a temperature of 200° C. or higher, preferably 280° C. or higher, and a pressure higher than the average pressure at the outlet and inlet of the moving catalyst bed reactor is introduced into the portions of the reactor where the catalyst is taken out therefrom and is again supplied thereto, whereby the decrease of the catalyst activity can be effectively prevented.
Patent•
30 Apr 1977
TL;DR: In this article, the authors proposed to reduce NOx in exhaust gas from stationary sources to harmless N2 and H2O by catalytic reduction in the presence of ammonia gas and activated carbon impregnated with ferric sulfate.
Abstract: PURPOSE:To effectively reduce NOx in exhaust gas from stationary sources to harmless N2 and H2O by catalytic reduction in the presence of ammonia gas and activated carbon impregnated with ferric sulfate
Patent•
06 Sep 1977
TL;DR: In this article, the authors proposed a method to prevent the decrease in activity of catlayst in reduction of SOx, NOx contained simultaneously in a flue gas with addition of NH3 by means of thermal decomposition of ammonia compounds and sulfuric acid formed on the surface of catalyst.
Abstract: PURPOSE:To prevent the decrease in activity of catlayst in reduction of SOx, NOx contained simultaneously in a flue gas with addition of NH3 by means of thermal decomposition of ammonia compounds and sulfuric acid formed on the surface of catalyst.
Patent•
01 Nov 1977
TL;DR: In this paper, an improved process for the preparation of urea from carbon dioxide and ammonia at elevated temperature and pressure was proposed, in which unconverted ammonia, substantially free of carbon dioxide, water and nitrogen, was recovered from a urea and ammonium carbamate containing liquid process stream.
Abstract: An improved process for the preparation of urea from carbon dioxide and ammonia at elevated temperature and pressure whereby unconverted ammonia, substantially free of carbon dioxide and water is recovered from a urea and ammonium carbamate containing liquid process stream. An urea and ammonium carbamate containing process stream is expanded to a pressure of between about 1 and 25 kg/cm 2 absolute and heated, thereby decomposing ammonium carbamate and forming a gas mixture containing ammonia, carbon dioxide and water vapor. The improvement comprises the steps of (a) introducing this gas mixture into a carbon dioxide separation column along with sufficient diluting water to form a first residual liquid phase, containing ammonia, carbon dioxide and from about 65 to 96 percent by weight water, in the bottom of such column, and separately removing therefrom an off-gas of carbon dioxide substantially free of ammonia, and the first residual liquid phase; (b) introducing this first residual liquid phase into a desorption column wherefrom a second off-gas containing ammonia, carbon dioxide and water vapor, is removed; (c) introducing the second off-gas into an ammonia separation column and separately removing therefrom a third off-gas of ammonia substantially free of carbon dioxide and water vapor, and a liquid phase containing ammonia, carbon dioxide and water; and (d) recycling the third gas phase back to the urea synthesis zone. The carbon dioxide separation column, desorption column and ammonia separation column are all operated at substantially the same pressure of between about 1 and 25 kg/cm 2 absolute.
Patent•
26 Apr 1977
TL;DR: In this article, the authors proposed to reduce NOx in exhaust gas at low temperature and high space velocity by contacting the gas with a catalyst obtained by supporting base metal components on natural zeolite which has been cation exchanged with a specific amount of alkali (earth) metals.
Abstract: PURPOSE:To reduce NOx in exhaust gas at low temperature and high space velocity by contacting the gas with a catalyst obtained by supporting base metal components on natural zeolite which has been cation exchanged with a specific amount of alkali (earth) metals.
Patent•
03 Mar 1977
TL;DR: In this paper, a method of removing NOx in heavily dust-laden gases such as exhaust combustion gases of glass melting furnaces by the catalytic reduction of the NOx was proposed.
Abstract: PURPOSE:A method of removing NOx in heavily dust-laden gases such as exhaust combustion gases of glass melting furnaces by the catalytic reduction of the NOx in the presence of NH3.
Patent•
06 Jan 1977
TL;DR: In this paper, dry catalytic reduction was used to remove nitrogen in exhaust gas from moving and standing sources by using catalysts for removing nitrogen from the exhaust gas, and the resulting nitrogen was removed.
Abstract: PURPOSE:Catalysts for removing nitrogen in exhaust gas from moving and standing sources by dry catalytic reduction.
Patent•
13 Jan 1977
TL;DR: In this article, the NH3 was used to reduce NOx in exhaust gases under mild reaction conditions of low temperatures and high space velocity, and the NOx was removed under mild conditions.
Abstract: PURPOSE:In catalytically reducing NOx in exhaust gases using NH3, NOx is effectively removed under mild reaction conditions of low temperatures and high space velocity.
Patent•
17 Jan 1977
TL;DR: In this article, the authors proposed a catalytic reduction of waste gas containing NO2 with ammonia using catalytic catalytic converters, which can reduce efficiently NO2 to N2.
Abstract: PURPOSE:Catalyst which can reduce efficiently NO2 to N2 by the catalytic reduction of waste gas containing NO2 with ammonia.
Patent•
08 Oct 1977
TL;DR: In this article, the authors proposed to reduce catalystically Ti(IV) ions to Ti(III) ions useful for reducing agent in an excellent yield in a short time by use of inexpensive apparatus by catalytic reduction of an acidic aqueous soltuion of Ti (IV) with hyrogen in the presence of a platinum group catalyst at a speficic pH.
Abstract: PURPOSE:To reduce catalystically Ti(IV) ions to Ti(III) ions useful for reducing agent in an excellent yield in a short time by use of inexpensive apparatus by catalytic reduction of an acidic aqueous soltuion of Ti(IV) with hyrogen in the presence of a platinum group catalyst at a speficic pH and in the presence of anions of a specific concentration.
Patent•
23 Apr 1977
TL;DR: In this paper, the NH3 wet dust removal is carried out to reduce alkali metal content in exhaust gas to less than 2mg/N m, so clogging of a catalyst bed is prevented.
Abstract: PURPOSE:In catalytic reduction of NOx in exhaust gas from sintering furnaces fro ore, etc. by using NH3 before addition of NH3 wet dust removal is carried out to reduce alkali metal content in exhaust gas to less than 2mg/N m , so clogging of a catalyst bed is prevented.
Patent•
05 Mar 1977
TL;DR: In this article, the authors proposed a catalytic reduction catalyst suitable for making NOx in exhaust gas nonhazardous by treatment with NH4, which is not spoilt by coexisting SOx and is little affected by the change of reaction temperature.
Abstract: PURPOSE:To offer a catalytic reduction catalyst suitable for making NOx in exhaust gas non-hazardous by treatment with NH4, which is not spoilt by coexisting SOx and is little affected by the change of reaction temperature.
Patent•
09 Feb 1977
TL;DR: In this article, NH3 is used to catalytically reduce NOx contained in exhaust gases emitted from internal combustion engines or nitric acid plants, at relatively high temperatures (above 400 deg.C) at high decomposition efficiency.
Abstract: PURPOSE:NOx contained in exhaust gases emitted from internal combustion engines or nitric acid plants, etc. is catalytically reduced by NH3 at relatively high temperatures (above 400 deg.C) at extremely high decomposition efficiency.
Patent•
16 Feb 1977
TL;DR: In this article, the authors proposed a selective catalytic purification of waste gases from nitrogen oxides, in which the waste gas to be treated is passed, together with gaseous ammonia, through the bed of a catalyst at a temperature of 100°-500° C.
Abstract: The method of selective catalytic purification of waste gases from nitrogen oxides consists in that the waste gas to be treated is passed, together with gaseous ammonia, through the bed of a catalyst at a temperature of 100°-500° C, a volumetric velocity of the waste gas of 5000 - 100000 hour-1 and a volumetric ratio of ammonia to nitrogen oxides of 0.7 - 1.5. The catalyst used in the proposed method is actually oxides of vanadium and of manganese that are taken in the weight ratio V2 O5 /Mn2 O3 of 0.1 - 30, the total quantity of the metal oxides being from 5 to 40 percent with respect to the total weight of the catalyst.
Patent•
17 Oct 1977
TL;DR: In this paper, the Pt group was used to promote decomposition of NOx and decrease amount of catalyst to be used by contacting NOx-containing gas and ammonia with Pt group catalyst under pressure.
Abstract: PURPOSE:To promote decomposition of NOx and to decrease amount of catalyst to be used by contacting NOx-containing gas and ammonia with Pt group catalyst under pressure.