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Showing papers on "Selective catalytic reduction published in 1987"


Journal ArticleDOI
TL;DR: In this paper, the titania supported vanadium oxide layers have been prepared and tested as catalysts for the selective catalytic reduction (SCR) of nitric oxide with ammonia.

154 citations


Journal ArticleDOI
TL;DR: In this article, the authors examined the possibilities of catalytic dinitrogen reduction in protic media and showed that an optimum catalyst should be able to form a binuclear complex MNNM bound to a polynuclear cluster of reductant atoms capable of transferring electrons to the coordinated N 2 molecule.

48 citations


Patent
03 Oct 1987
TL;DR: In this paper, a two-stage process is provided in which a catalytic reduction stage (30) for the substantial removal of the nitrogen oxides, with the addition of ammonia (50), and an additional catalytic oxidation stage (40) in which the residual oxygen present in the prepurified waste gas is utilised for oxidation of hydrocarbons, carbon monoxide and excess ammonia, are connected in series.
Abstract: In order to reduce emissions of nitrogen oxides, hydrocarbons and carbon monoxide in the operation of stationary internal-combustion engines having excess air coefficients greater than 1, a two-stage process is provided in which a catalytic reduction stage (30) for the substantial removal of the nitrogen oxides, with the addition of ammonia (50), and a catalytic oxidation stage (40) in which the residual oxygen present in the prepurified waste gas is utilised for oxidation of hydrocarbons, carbon monoxide and excess ammonia, are connected in series. Any leakage of ammonia from the first catalytic stage is decreased by the following oxidation step. A reduction in the amount of the pollutant components comprising nitrogen oxides, hydrocarbons and carbon monoxide is achieved at virtually all excess air coefficients greater than 1.

23 citations


Patent
20 Jan 1987
TL;DR: In this paper, a process for the purification of exhaust gases containing oxides of nitrogen and sulfur obtained from combustion installations and industrial production processes was described by selective catalytic reduction of the nitric oxides with ammonia, subsequent catalytic oxidation of sulfur dioxide with oxygen and conversion into sulfuric acid of the sulfur trioxide obtained.
Abstract: A process is described for the purification of exhaust gases containing oxides of nitrogen and sulfur obtained from combustion installations and industrial production processes by selective catalytic reduction of the nitric oxides with ammonia, subsequent catalytic oxidation of sulfur dioxide with oxygen and conversion into sulfuric acid of the sulfur trioxide obtained.

22 citations


Patent
22 Apr 1987
TL;DR: In this article, a process for reducing the nitrogen oxide content in waste gases of combustion installations is described, where nitrogen oxide-containing waste gases are conducted past temperature-resistant structures which are coated with a mixture of one or more aluminosiliciates of the faujasite group, silica sol and/or silicates and a copper compound.
Abstract: A process for reducing the nitrogen oxide content in waste gases of combustion installations is disclosed. The present process is a catalytic reduction with ammonia wherein the nitrogen oxide-containing waste gases are conducted past temperature-resistant structures which are coated with a mixture of one or more aluminosiliciates of the faujasite group, silica sol and/or silicates and a copper compound.

15 citations


Patent
07 Aug 1987
TL;DR: In this paper, 2.2-way and 3-way catalyst compositions comprising tin (IV) oxide (SnO2) and chromium (VI) oxide(CrO3) for use in catalytic converters for vehicle exhaust gas systems, such catalyst compositions being effective in the catalytic oxydation of carbon monoxide and unburnt hydrocarbons, and in the reduction of nitrogen oxides contained in the vehicle exhaust.
Abstract: 2-way and 3-way catalyst compositions comprising tin (IV) oxide (SnO2) and chromium (VI) oxide (CrO3) for use in catalytic converters for vehicle exhaust gas systems, such catalyst compositions being effective in the catalytic oxydation of carbon monoxide and unburnt hydrocarbons, and in the catalytic reduction of nitrogen oxides contained in the vehicle exhaust.

14 citations


Journal ArticleDOI
TL;DR: In this paper, the interaction between NO and CO over CuxCo3−xO4 spinels has been studied and it has been found that the two reactions of NO reduction, to N2O and N2, respectively, are accelerated by the increase of Cu content (x).
Abstract: The interaction between NO and CO over CuxCo3−xO4 spinels (0≤x≤1) has been studied. It has been found that the two reactions of NO reduction, to N2O and N2, respectively, are accelerated by the increase of Cu content (x). With the second reaction acceleration occurs only at x>0.5. This is attributed to the presence of different centers on which N2O and N2 are formed.

13 citations


Patent
12 Nov 1987
TL;DR: In this article, an ammonia/air mixture has been introduced through nozzles distributed over the cross-section of the flue gas duct at about the flow velocity of the liquid nitrogen oxides.
Abstract: Ammonia gas is introduced by means of a feeding device into the flue gas duct of a large boiler, for example of a power station, having a flow cross-section of at least 3 m , into the flue gas stream flowing through the flue gas duct at a flow velocity of 10 to 30 m/s for a subsequent reduction, in particular a selective catalytic reduction, of the nitrogen oxides contained in the flue gas to nitrogen and water at a temperature of 300 to 450 DEG C. Hitherto, an ammonia/air mixture has been introduced through nozzles distributed over the cross-section of the flue gas duct at about the flow velocity of the flue gas, a distribution grid being provided downstream thereof, if desired. In order to effect the ammonia feed with higher operational reliability and lower energy consumption and to achieve a perfect and more complete mixing over a comparatively short mixing length, it is provided that the feeding device has jet pipes 7, ending in the direction of the flue gas flow in the flue gas duct 1, for feeding flue gas under pressure at a rate of 1 to 5 % by volume of the flue gas stream and at a flow velocity of at least 80 m/s at the jet pipe end, the jet pipes being connected to a flue gas compressor (2) which draws the flue gas from the flue gas duct via a flue gas branch line (3) and draws the ammonia gas.

13 citations


Patent
Keck Lindsey1
19 May 1987
TL;DR: An SCR catalyst consisting of vanadium carried by a mixture of ceria and alumina on a support was proposed in this paper, where vanadium was replaced by vanadium dioxide.
Abstract: An SCR catalyst consisting essentially of vanadium carried by a mixture of ceria and alumina on a support.

12 citations


Patent
05 Feb 1987
TL;DR: In this article, a flue gas stream having passed a desulfurization plant 2 enters a reactor 6 flowing through an activated carbon bed and is discontinuously blended with ammonia to achieve a low ammonia content of the flue gases leaving the reactor, while maintaining a high efficiency of nitrogen oxide removal.
Abstract: A flue gas stream having passed a flue gas desulfurization plant 2 enters a reactor 6 flowing through an activated carbon bed. The flue gas entering the reactor continuously is discontinuously blended with ammonia, thereby achieving a low ammonia content of the flue gas leaving the reactor, while maintaining a high efficiency of nitrogen oxide removal. The duration of ammonia addition and the rate of flow at which ammonia is added to the flue gas stream are controlled as a function of the desired efficiency of nitrogen oxide removal and the ammonia concentration measured in the reactor.

11 citations


Patent
Pui K. Wong1
29 Dec 1987
TL;DR: A polymeric polyalcohol of high molecular purity was obtained by sodium botohydride reduction of a linear alternating copolymer of carbon monoxide and ethylene in a liquid-phase solution in hexafluoroisopropanol at ambient temperature and pressure as discussed by the authors.
Abstract: A polymeric polyalcohol of high molecular purity is obtained by sodium botohydride reduction of a linear alternating copolymer of carbon monoxide and ethylene in a liquid-phase solution in hexafluoroisopropanol at ambient temperature and pressure.

Patent
05 Oct 1987
TL;DR: In this paper, the authors describe a firing installation with a furnace and a boiler, in which ammonia NH3 is mixed to the flue gas stream, whereby the nitrogen oxides are reduced in a reaction chamber with catalysts.
Abstract: In a firing installation with a furnace (1) and a boiler (2), ammonia NH3 is admixed to the flue gas stream, whereby the nitrogen oxides are reduced in a reaction chamber (5) with catalysts. In a flue gas wet-scrubbing unit (7) downstream of the reaction chamber (5), the unreacted ammonia is dissolved in the scrubbing water. The latter is passed through a connection line (8) into a stripping column (9), where the ammonia is stripped from the scrubbing water and mixed with introduced air. This air enriched with ammonia NH3 is passed as combustion air into the furnace (1). As a result, the nitrogen oxide reduction can be operated with a large ammonia excess, so that a degree of nitrogen oxide separation of any desired high level can be achieved. In addition, the ammonia stripped out in the stripping column (9) is passed to the combustion, where it reacts with the NOx present, whereby the ammonia consumption is substantially reduced. This can also be achieved in combination with the SNCR process. … …

Patent
18 Sep 1987
TL;DR: In this article, an excess of ammonia is injected and this ammonia-enriched flue gas stream is first passed over a known reduction catalyst and then over an oxidation catalyst for oxidising the remaining ammonia excess.
Abstract: A catalyst arrangement (8) in a flue gas line (2) for reducing nitrogen oxides in the presence of oxygen involves the problem of further reducing the fraction of unreduced nitrogen oxides which remain in the flue gas. For this purpose, an excess of ammonia is injected and this ammonia-enriched flue gas stream is first passed over a known reduction catalyst (12) and then over an oxidation catalyst (13) for oxidising the remaining ammonia excess. The catalyst arrangement according to the invention is especially suitable for use in an industrial combustion installation.

Patent
05 May 1987
TL;DR: In this paper, the use of macroporous weakly-basic anion exchangers, charged with palladium or platinum and based on crosslinked polystyrene, as catalysts for the removal of oxygen from aqueous media by catalytic reduction, is described.
Abstract: Catalyst resins for the catalytic reduction of oxygen in aqueous media, the preparation of the catalyst resins, and new catalyst resins A b s t r a c t The invention relates to the use of macroporous weakly-basic anion exchangers, charged with palladium or platinum and based on crosslinked polystyrene, as catalysts for the removal of oxygen from aqueous media by catalytic reduction, a process for the preparation of these cata-lyst resins, and new macroporous weakly-basic anion exchangers, charged with palladium or platinum and based on crosslinked polystyrene, in which the amino groups are primary or secondary amino groups.

Patent
29 Sep 1987
TL;DR: In this article, a catalyst for reducing nitrogen oxides in waste gases is based on exchanged zeolite Y, if desired in a matrix with further doping, and it is shown that Y can be used for a variety of applications.
Abstract: A catalyst for reducing nitrogen oxides in waste gases is based on exchanged zeolite Y, if desired in a matrix with further doping.

Patent
Hyun Jong Jung1
30 Jun 1987
TL;DR: An SCR catalyst consisting of at least one oxysulfur compound of manganese, nickel or mixtures thereof, carried by a supported mixture of ceria and alumina is characterized by its high activity and by its stability even when used in the absence of sulfur oxides.
Abstract: An SCR catalyst consisting essentially of at least one oxysulfur compound of manganese, nickel or mixtures thereof, carried by a supported mixture of ceria and alumina. The catalyst is characterized by its high activity and by its stability even when used in the absence of sulfur oxides.

PatentDOI
TL;DR: In this article, a heat exchanger is traversed from a top section to a bottom section by a plurality of heat storage elements which are separately movable and are charged by the flue gas transversely to their direction of movement.
Abstract: An apparatus and process for catalytically reducing noxious substances in flue gas wherein a heat exchanger is traversed from a top section to a bottom section by a plurality of heat storage elements which are separately movable and are charged by the flue gas transversely to their direction of movement. At least a portion of the heat storage elements are provided with a catalyst coating. Flue gas cooled downstream of a desulfurization system is conducted through the bottom section of the heat exchanger where it is preheated by the heat storage elements and is then heated to a predetermined reaction temperature by an external heating means. Ammonia is added and the flue gas is conducted at least once through at least one middle section of the heat exchanger for the catalytic reduction of the noxious substances. Then, the flue gas is conducted through the top section of the heat exchanger so as to cool it to a predetermined chimney entrance temperature. Not only is a decrease in catalytic activity prevented, but an adverse affect on the efficiency of the catalyst due to leakages from a gas preheater for the flue gas is prevented so that the heat exchanger can be used advantageously downstream of a desulfurization system.

Patent
12 May 1987
TL;DR: In this article, a process for removing ammonia from waste water of a power station is described. But this process requires that gaseous ammonia to be removed is fed, together with oxygen, in particular together with air, to at least one catalyst (8) which then gives off nitrogen and water.
Abstract: The invention relates to a process for removing ammonia. It is provided that gaseous ammonia to be removed is fed, together with oxygen, in particular together with air, to at least one catalyst (8) which then gives off nitrogen and water. To remove ammonia from ammonia-containing waste water, in particular from the waste water of a power station, the ammonia, in a mass transfer column (2) is transferred from the water into a gas stream. A mixture of gaseous ammonia, oxygen and other gases is fed via a heat exchanger (6) and a heater (7) to the inlet of a catalyst (8). Instead of a catalyst (8), a combination of a noble metal catalyst (10) and a mixed oxide catalyst (11) can be used. Nitrogen and water are given off at the catalyst exit. To form a virtually closed gas circulation, the exit of the catalyst (8) or of the mixed oxide catalyst (11) is connected via the heat exchanger (6) and a fan (9) to the gas feedline (4) of the mass transfer column (2).

Patent
12 Feb 1987
TL;DR: In this article, a method and apparatus for denitration of an NOx-containing untreated gas from an off-gas source is described, and control means for regulating the flow rate of the untreated bypass gas stream are provided.
Abstract: A method and apparatus is disclosed for the denitration of an NOx-­containing untreated gas from an off-gas source (7). According to the method ammonia (6) is introduced into the NOx-containing untreated gas in known manner prior to passage through a denitration reactor (2) packed with a catalyst effective to cause the catalytic reduction of the nitrogen oxides in the presence of ammonia. According to the invention a portion of the untreated gas (4) is caused to bypass the denitration reactor (2) and is subsequently recombined with the treated gas from the reactor. Control means (5) are provided for regulating the flow rate of the untreated bypass gas stream.

Patent
13 Nov 1987
TL;DR: For the removal of SO x and NO x from effluent gas, the gas, before being passed through a Selective Catalytic Reduction (SCR) catalyst bed for reduction of at least a part of the nitrogen oxides in the gas as discussed by the authors, is subjected to at least substantially complete desulfurization in a coke bed.
Abstract: For the removal of SO x and NO x from effluent gas, the gas, before being passed through a Selective Catalytic Reduction catalyst bed for reduction of at least a part of the nitrogen oxides in the gas, is subjected to at least substantially complete desulfurization in a coke bed. The desulfurized and denoxed gas can also be passed through a coke bed in which the ammonia which has not reacted in the SCR-catalyst bed is removed from the gas.

Patent
30 Jun 1987
TL;DR: An SCR catalyst consisting of iron sulfate or oxysulfur iron compound carried by a mixture of ceria and alumina on a support is a SCR as discussed by the authors.
Abstract: An SCR catalyst consisting essentially of iron sulfate or oxysulfur iron compound carried by a mixture of ceria and alumina on a support.

Patent
23 Oct 1987
TL;DR: In this article, the authors proposed a method for the thermal recovery of pure ammonia from ammonia water containing hydrogen sulphide and/or carbon dioxide, which is used in the processing of waste waters which occur in the upgrading of petroleum and coal.
Abstract: The invention comprises the thermal recovery of pure ammonia from ammonia water containing hydrogen sulphide and/or carbon dioxide. The process is to be designed in such a way that it is not necessary to feed in pure water for the separation of the inert gas/ammonia mixture and for the ammonia scrub. This is achieved by, after distillative deacidification, passing the ammonia water to be processed or a part thereof in countercurrent to the inert gas/ammonia mixture. Another part of the deacidified ammonia water is used for scrubbing the ammonia removed in the thermal volatilisation of ammonia. The enriched ammonia water coming from the inert gas/ammonia separation is fed to the thermal volatilisation of ammonia and the ammonia water coming from the scrub is, after a large part of the ammonia has been driven off, fed to the distillative deacidification. The invention is used in the processing of waste waters which occur in the upgrading of petroleum and coal.


Patent
23 Jul 1987
TL;DR: In this paper, a method of preparing test gas mixtures containing nitrogen oxides such as NO and/or NO2 for calibrating NO/NO2 analysers is described, where ammonia (NH3) is added to a carrier gas containing oxygen, in particular air, in a certain amount to achieve a certain concentration of ammonia in the carrier gas, in that the gas mixture leaving the catalyst material serves as test gas mixture.
Abstract: The invention relates to a method of preparing test gas mixtures containing nitrogen oxides such as NO and/or NO2 for calibrating NO/NO2 analysers. The method is characterised in that ammonia (NH3) is added to a carrier gas containing oxygen, in particular air, in a certain amount to achieve a certain concentration of ammonia in the carrier gas, in that the carrier gas/ammonia mixture is passed over or through the catalyst material at a certain temperature, which catalyst material promotes a reaction of the ammonia with the oxygen, and in this process, the ammonia is burnt with oxygen at high efficiency to form nitrogen oxide (NO) and nitrogen dioxide (NO2) and possibly further combustion products, and in that the gas mixture leaving the catalyst material serves as test gas mixture. The invention also relates to a device for carrying out such a method.

Book ChapterDOI
TL;DR: In this paper, the influence of macromolecular carbon deposits, catalytic poisons, sintering, and destruction of pellets both on the deactivation and life of a copper catalyst used for the selective gas-phase catalytic reduction has been discussed.
Abstract: The influence of macromolecular carbon deposits, catalytic poisons, sintering, and destruction of pellets both on the deactivation and life of a copper catalyst used for the selective gas-phase catalytic reduction has been discussed. The catalyst applied in an industrial tube non-isothermic reactor is deactivated mainly by carbon deposits and sintering. The contribution of catalytic poisons is in fact negligible if their concentration in the processed raw material is lower than 0.5 ppm. It has been proved that the support composition, the presence of poisons, and the amount of 1, 3-dinitrobenzene in the raw material can have the major influence on the formation of carbon deposits. The catalyst sintering occurs nearly exclusively in the starting period of the operational cycle. The slow destruction of pellets has a positive influence on the catalyst life.

Patent
30 Nov 1987
TL;DR: In this article, a process of catalytically reducing NO contained in a gas which contains SO2 and NO is described, where the NO is reduced with NH3, which is mixed with the mixture of V2O5, MnO2, CuO, Fe2O3, NiO and/or Y 2O3.
Abstract: not available for EP0274148Abstract of corresponding document: US4847054A process of catalytically reducing NO contained in a gas which contains SO2. The NO is reduced with NH3, which is admixed to the gas which contains SO2 and NO. The mixture is supplied to the catalyst at a rate of 0.2 to 20 standard liters per minute and per gram of catalyst and is reacted with the latter in a fluidized bed at a temperature between 185 DEG and 500 DEG C. and under normal pressure. The catalyst has a particle size between 0.1 and 3 mm and is composed of an acid support and an active component, which consists of V2O5, MnO2, CuO, Fe2O3, NiO and/or Y2O3 and has been applied to the support in a quantity of 0.5 to 20% by weight. It is proposed that part of the catalyst is removed from the fluidized bed and is regenerated and returned to the fluidized bed.

Patent
26 May 1987
TL;DR: In this article, N-methyl-2(or 7)-homopiperazinone is used as a raw material and subjected to catalytic reduction usually at 100-350 deg.C under 5-500 kg/cm, preferably 30-150kg/cm pressure in a dioxane solvent in the presence of a copper-chromium catalyst.
Abstract: PURPOSE:To obtain the titled compound useful as an intermediate for pharmaceuticals, in high yield and purity, by catalytically reducing N-methyl-2(or 7)-homopiperazinone in the presence of a dioxane solvent using a specific catalyst and cooling the reaction system immediately after the completion of reduction. CONSTITUTION:N-methyl-2(or 7)-homopiperazinone is used as a raw material and subjected to catalytic reduction usually at 100-350 deg.C, preferably 150-300 deg.C under 5-500kg/cm , preferably 30-150kg/cm pressure in a dioxane solvent in the presence of a copper-chromium catalyst. Immediately after the completion of the reduction, the reaction system is cooled to obtain the objective compound. The cooling is carried out e.g. by using a continuous reduction reactor, by taking the reaction system out of a batch autoclave reactor in the form of vapor or liquid, etc., immediately after the reduction, etc. A commercially available low-cost copper-chromium catalyst can be used as it is as the above catalyst.

Book ChapterDOI
01 Jan 1987
TL;DR: In this paper, the authors proposed a method or catalytic reduction of nitrogen oxides by ammonia, which has found the widest acceptance among secondary secondary measures taken to reduce NOx emissions from large combustion facilities.
Abstract: Of the various secondary measures taken to reduce NOx emissions from large combustion facilities, the method or catalytic reduction of nitrogen oxides by ammonia has found the widest acceptance.

Patent
30 Jan 1987
TL;DR: In this article, a two-stage exhaust gas heater was placed after an ammonia oxidizer, and an ammonia catalytic reduction denitration apparatus was attached to the outlet channel of the former stage heater.
Abstract: PURPOSE:To carry out the denitration reaction at optimum gas temperature, by placing two-stage exhaust gas heater after an ammonia oxidizer, and attaching an ammonia catalytic reduction denitration apparatus to the outlet channel of the former stage heater. CONSTITUTION:NH3 evaporated by the evaporator 1 is mixed with air supplied through the compressor 3 and the air heater 5, and oxidized in the oxidizer 3. The produced nitrogen oxide is passed through the heater 5, the first exhaust gas heater 7A and the second exhaust gas heater 7B to effect the heat-exchange, condensed in a condenser cooler 9, introduced into the absorption column 11, and absorbed in water to obtain nitric acid. The exhaust gas exhausted from the absorption column 11 is introduced into the heater 7A through the line 15 to effect the heat-exchange and to control the gas temperature to 310-350 deg.C and gas pressure to 6-7kg/cm G at the outlet-side line D. The conditioned gas is supplied to the ammonia catalytic reduction denitration apparatus, denitrated by ammonia reduction, and supplied through the heater 7B to the steam turbine 13 to recover the energy.

01 Jan 1987
TL;DR: Engelhard vandia-titania-based catalysts have been used for power plant applications as discussed by the authors, and the results of commercial systems using this catalyst demonstrating favorable long-term operation is discussed along with comparisons of published results for other catalysts.
Abstract: In late 1979, Engelhard renewed development efforts directed at vanadia type catalysts which were initially used in Europe for nitric acid plants, and vanadia-titania catalysts which were later used extensively in Japan for power plants The vanadia-titania basic composition was combined with the earlier extensive Engelhard experience developed during the commercial pioneering effort which resulted in the practical catalyzing of ceramic honeycomb supports The result was the high activity, high cell density, coated ceramic honeycomb catalyst, now available for use downstream of utility FGD units, gas turbines, stationary engines, industrial heaters and boilers This paper reports key performance characteristics of Engelhard vandia-titania based catalyst The results of commercial systems using this catalyst demonstrating favorable long-term operation is also discussed along with comparisons of published results for other catalysts