Showing papers on "Selective catalytic reduction published in 1985"

Evaluation of a catalytic reduction technique for the measurement of total reactive odd-nitrogen NOy in the atmosphere

Abstract: A catalytic reduction technique for the measurement of total reactive odd-nitrogen NO y in the atmosphere was evaluated in laboratory and field tests. NO y component species include NO, NO2, NO3, HNO3, N2O5, CH3COO2NO2(PAN), and particulate nitrate. The technique utilizes the reduction of the higher oxides to NO in reaction with CO on a metal catalyst and the subsequent detection of NO by chemiluminescence produced in reaction with O3. The efficiency and linearity of the conversion of the principal NO y species were examined for mixing ratios in the range of 0.1 to 100 parts per billion by volume (ppbv). Results of tests with Au, Ni, and stainless steel as the catalyst in the temperature range of 25–500°C showed Au to be the preferred catalyst. NH3, HCN, N2O, CH4, and various chlorine and sulfur compounds were checked as possible sources of NO y interference with the Au catalyst. The effects of pressure, O3, and H2O on NO y conversion were also examined. The results of the checks and tests in the laboratory showed the technique to be suitable for initial NO y measurements in the atmosphere. The technique was subsequently tested in ambient air at a remote ground-based field site located near Niwot Ridge, Colorado. The results of conversion and inlet tests made in the field and a summary of the NO y data are included in the discussion.

The electrochemical reduction of co2 catalyzed by ruthenium carbonyl complexes

Abstract: The catalytic reduction of CO2 has been succesfully performed under the controlled potential electrolysis of [Ru (bpy)2 (CO)2](PF6)2 (bpy=2,2′-bipyridine) in a CO2-saturated H2O/DMF solution. Formic acid and CO as well as H2 are formed in alkaline conditions, while only CO and H2 are evolved in acidic conditions.

Method for recovering denitrating catalyst for ammonia catalytic reduction

Abstract: A method for recovering a denitrating catalyst for ammonia catalytic reduction which is characterized by treating the denitrating catalyst for ammonia catalytic reduction, in which a performance has deteriorated, with at least one selected from the group consisting of SO4 2- compounds, sulfur compounds and sulfonic acid compounds in order to replenish the catalyst with a sulfur content.

Vanadium oxide catalyst for nitrogen oxide reduction and process using the same

Abstract: A catalyst composition effective for selective catalytic reduction of nitrogen oxides with ammonia in a gas stream has an upstream section comprising a phosphorus getter comprised of a phosphorus retaining material, e. g., activated alumina, and a downstream section comprising a vanadium oxide containing catalyst, e. g., a vanadia/titania catalyst. It has surprisingly been found that vanadium oxide catalysts are poisoned by phosphorus which may be contained in the form of phosphorus contaminant compounds in the gas to be treated, so that the positioning of a phosphorus-retaining material upstream of the catalyst prolongs catalyst life. In operation, the gas to be treated is passed first through the phosphorus getter upstream section of the catalyst composition and then contacted in the presence of ammonia with the downstream section catalytic material.

Process for separating out nitrogen oxides

Abstract: The invention describes a process for separating out nitrogen oxides from a combustion exhaust gas, which process comprises the addition of ammonia to the combustion exhaust gas in order to react the nitrogen oxides contained in the exhaust gas with the ammonia and thus to decompose the nitrogen oxides, while a heat exchange is effected between the exhaust gas and air for combustion, using an air preheater of the rotary heat exchanger type.

Regenerating method of denitration catalyst

Abstract: PURPOSE: To perform easily the regeneration of a denitration catalyst by attriting and removing the surface of an ammonia catalytic reduction denitration catalyst (especially a denitration catalyst for a coal-fired boiler) which is deteriorated in the performance with the use of a powdery material. CONSTITUTION: The surface of a catalyst is attrited by inserting a nozzle 5 of a spray gun into the catalyst holes 2 of the catalyst 1 having a honeycomb shape and colliding a powdery material such as a fly ash, fine sand or iron powder fed from a vessel 4 against the surface of the catalyst by means of the compressed air. The nozzle number of the spray gun may be made equal to the number of the holes of the catalyst. The part to be attrited may be made nearly to the surface of the catalyst and in the example wherein it is attrited in 30μ or 35μ thickness, 90.1% or 95.5% rate of recovery is respectively exhibited. Furthermore the rate of recovery is shown in the following formula {(B-C)/(A-C)}×100% (A is the denitration degree of a fresh catalyst, B is the denitration degree after the regenerating treatment and C is the denitration degree before the regenerating treatment). COPYRIGHT: (C)1986,JPO&Japio

Method of preparation of catalyst and catalyst prepared by the method for converting nitrogen oxides in exhaust gases

Abstract: A catalyst for removing nitrogen oxides from an exhaust gas comprises a composite oxide or mixture of niobic acid or niobium oxide with iron oxide or hydrated iron oxide. The catalyst contains atoms of niobium and atoms of iron in a ratio Nb/Fe not exceeding about 1. The catalyst is useful for converting nitrogen oxides in an exhaust gas to nitrogen gas by contacting the exhaust gas with the catalyst in the presence of a reducing gas, such as ammonia. The catalyst can be prepared by impregnation or coprecipitation.

Process for the continuous removal and recovery of ammonia from waste waters of flue-gas purification plants

Abstract: The invention consists in a process for the continuous, automatically controlled removal and recovery of ammonia from waste waters of flue-gas purification plants, in which the flue gas is admixed, for the purpose of catalytic reduction of nitrogen oxides, with ammonia of which a residual amount not consumed is then scrubbed out in a scrubbing stage connected downstream for the purpose of removing sulphur oxides and other noxious gases and in this manner is taken up in the waste water removed from the process. In order to process this waste water, which contains ammonia in the form of ammonium salts, so as to produce once more a water which is not harmful to the environment, the precipitation of sparingly soluble metal compounds, which is known per se for waste waters of this type, is in this case carried out at a considerably higher pH in order to completely convert ammonia into the form where it is dissolved as a gas. In this form the ammonia can then be driven off from the alkalinised waste water by means of hot air, which is expediently drawn from a steam generation plant, and can be returned to the flue-gas purification process while heat losses are minimised.

Process for regenerating carbon-containing adsorbents (adsorption agents)

Abstract: Brown coal coke used as adsorbent is regenerated in a moving bed by washing (scrubbing) for adsorptive removal of sulphur dioxide and catalytic reduction of nitrogen oxides to nitrogen. The regeneration is carried out by washing sulphuric acid and soluble sulphates out of the brown coal coke with water at atmospheric pressure in a temperature range of 20-95 DEG C. The washing out can also be carried out under increased (superatmospheric) pressure at 5 bar and at an elevated temperature of 150 DEG C. Another method of regeneration comprises first driving out the sulphuric acid with superheated steam and subsequently washing out the soluble sulphates with water in the temperature range of 20-95 DEG C. The treatment of the brown coal coke in a container is carried out continuously or batchwise (discontinuously), with the brown coal coke being treated in countercurrent or cocurrent mode with the steam or water. The untreated waste water (effluent) from the regeneration is used for wetting of ash which is produced in the combustion process from which the flue gas arises. In addition, the waste water obtained can again be supplied to the washer after removal of the sulphuric acid.

Apparatus for the realization of a process to remove nitrogen oxides from exhaust gases.

Abstract: An apparatus for the realization of a process for the removal of nitrogen oxides from exaust gases wherein the hot exaust gases are mixed with gaseous ammonia or sprayable liquid ammonia and then brought through a catalyst lattice. In that catalyst lattice the nitrogen oxides with the ammonia are reduced to form gaseous nitrogen and water vapor. The catalyst lattice is made to form a ceramic molecular sieve. The size of the cross - sectional diameter of the passages of that sieve is below the critical diameter of ammonia.

Production of 1-(4-isopropylphenyl)ethylamine

Abstract: PURPOSE:To produce the titled compound useful as a purely synthetic basic optical resolution agent, easily, in high yield, by the catalytic reduction of p- isopropylacetophenone in the presence of a nickel catalyst and ammonia. CONSTITUTION:The objective compound can be produced by the catalytic reduction of p-isopropylacetophenone in the presence of a nickel catalyst (e.g. Raney nickel) and ammonia in a solvent such as methanol at 50-150 deg.C and 5-150kg/ cm pressure, preferably at 70-130 deg.C and 10-100kg/cm pressure, for 20-90min. The amount of the catalyst is 0.5-30wt%, preferably 2-20wt% based on p- isopropylacetophenone in terms of nickel, and that of ammonia is >=2mol, preferably 3-7mol per 1mol of p-isopropylacetophe none.

Catalyst, method of preparation and its use in converting nitrogen oxides in exhaust gases

Abstract: A catalyst for removing nitrogen oxides from an exhaust gas comprises a composite oxide or mixture of niobic acid or niobium oxide with iron oxide or hydrated iron oxide. The catalyst contains atoms of niobium and atoms of iron in a ratio Nb/Fe not exceeding about 1. The catalyst is useful for converting nitrogen oxides in an exhaust gas to nitrogen gas by contacting the exhaust gas with the catalyst in the presence of a reducing gas, such as ammonia. The catalyst can be prepared by impregnation or coprecipitation.

Denitration apparatus by catalytic reduction with ammonia for reprocessing off gas

Abstract: PURPOSE:To prevent the condensation and deposition of nitric acid and ammonium nitrate on the inner wall surface of a denitration apparatus by insulating the denitration apparatus by catalytic reduction with ammonia, and providing a gas circulating system provided with a removing apparatus of nitric acid and ammonium nitrate to the inside of the apparatus. CONSTITUTION:The denitration apparatus 1 by catalytic reduction with ammonia can be insulated from an upstream and a downstream treating apparatus, and a circulating system 5 of the gas in the system provided with a removing apparatus 4 of nitric acid and/or ammonium nitrate is provided to the inside of the denitration apparatus 1 by catalytic reduction with ammonia. The denitration apparatus by catalytic reduction with ammonia for reprocessing off gas, wherein the condensation of the deposition of corrosive nitric acid and ammonium nitrate on the inner wall surface of the denitration apparatus can be prevented even during the stoppage including the stoppage due to an emergency, can be obtained.

Electrochemistry of metalloporphyrins and their catalytic reduction of oxygen at carbon electrodes

Abstract: 2. When an image on the film is obliterated with a round black m ark, it is an indication o f either blurred copy because o f m ovem ent during exposure, duplicate copy, o r copyrighted m aterials tha t should not have been filmed. For blurred pages, a good image o f the page can be found in the adjacent frame. If copyrighted materials were deleted, a target note will appear listing the pages in the adjacent frame.

Ammonia catalytic reduction and denitration apparatus

Abstract: PURPOSE:To hold the NOx-concn. at the outlet of a denitration apparatus to a low level correspondig to the abrupt change in a NOx-concn., in an ammonia catalytic reduction and denitration apparatus, by arranging an adsorbing tower packed with a NOx-adsorbent to the upstream side of the denitration reaction apparatus. CONSTITUTION:NOx-containing exhaust gas is introduced into an adsorbing tower 2 from an inlet duct 1 and the adsorbing tower 2 is packed with an inorg. porous adsorbent such as zeolite for performing NOx-adsorption. The exhaust gas passing this adsorbing tower 2 is heated while guided to a preheater 5 and NH3 is injected from an NH3 injection port. Subsequently, the exhaust gas is guided to a denitration reactor 8 to be reacted with a catalyst while the treated gas is exhausted from a duct 9. The NH3 injection amount is operated and controlled on the basis of signals from a gas flow meter 10, an inlet NOx-meter 11, an outlet NOx-meter 16 and an NH3 flow meter 14 by a control circuit 15.

METHOD FOR LOWERING THE NOx CONCENTRATION IN EXHAUST GAS

Abstract: A method for lowering the NOx concentration in exhaust gas by means of a catalytic reduction of NOx gas with utilization of a washable catalyst, provides a solution enabling, while preserving the advantages of the known method according to DE-A 31 07 117, to avoid this danger and which is convenient to a wide range of exhaust gas, ie not limited particularly to nitric acid plants This result is obtained because the reduction with utilization of unsaturated hydrocarbons is carried out at a temperature equal or lower than 180 C