Showing papers on "Selective catalytic reduction published in 1979"

Three-way catalytic process for gaseous streams

Abstract: A process for the catalytic combustion of carbon monoxide and hydrocarbons and the catalytic reduction of the oxides of nitrogen contained in a gas stream. The process involves intimately contacting the gaseous stream with a catalyst bed comprising copper metal or copper ion and a high silica zeolite.

Process for the catalytic reduction of nitrogen oxides in gaseous mixtures

Abstract: A process for the reductive removal of a nitrogen oxide from a gaseous stream, particularly a stream containing oxygen, water, sulfur dioxide, nitrogen oxide and nitrogen, by contacting the stream with ammonia in the presence of a mixture of two catalysts. The first catalyst comprises copper or a copper compound, preferably copper sulfate supported on a porous carrier material. The second catalyst is a combination of metals or compounds thereof, preferably sulfates of vanadium and iron or tungsten and iron, also dispersed on a porous carrier material.

Integrated ammonia-urea process

Abstract: An integrated ammonia-urea process is disclosed which uses as the starting gas mixture a stream coming, for example, from steam reforming of hydrocarbons, carbon dioxide being stripped from the stream by the action of a very concentrated ammonia solution (above 70% by wt) first and the the action of an ammoniated solution of ammonium carbonate secondly, a solution of ammonium carbamate being obtained together with a gas stream composed of nitrogen and hydrogen; sending the carbamate solution to the urea reactor, discharging from the urea reactor the urea solution containing unconverted carbamate and excess ammonia, decomposing said carbamate and sending evolved ammonia to the urea reactor again along with carbon dioxide, discharging the urea solution having now 50% of the original carbamate to an adiabatic stripper in which the stripping gas is essentially composed of hydrogen and nitrogen, removing ammonia and carbon dioxide with water from the adiabatic stripper and condensing ammonia and carbon dioxide by heat exchange, sending the stream of hydrogen and nitrogen to methanization and ammonia synthesis and concentrating the urea solution directly until obtaining a urea melt.

Production of catalyst and denitration method

Abstract: PURPOSE:To remove NOx with high efficiency while controlling oxidation of SO2 to SO3 by adding oxide of W, Sn, Mn, Co or Zn to a titanium oxide carrier and then supporting a metal (oxide) for catalytic reduction denitration with NH3. CONSTITUTION:To 1 part by wt. of a titanim oxide carrier is previously added 0.01-1, pref. 0.05-0.2 part of oxide of W, Sn, Mn, Co or Zn. 0.01-1 part of Pt, V2O5, CuO, Fe2O3, WO3, etc. is then supported as an active component on 1 part of te carrier. Exhaust gas contg. NOx and SO2 is brought into contact with the resulting catalyst at above 200 deg.C in the presence of NH3 in an amt. of 0.5-3 times as much as the stoichiometric amt. to the NOx content.

Effect of oxygen on the catalytic reduction of nitric oxides by carbon monoxide over NiO

Abstract: The catalytic reduction of nitrogen oxides (NO, N2O and NO2) by carbon monoxide over NiO has been studied in the temperature range from 200 to 500°C. The reaction of NO2 with CO is much faster than that of NO with CO. The former reaction in the presence of a 3–4-fold excess of oxygen proceeds at a significant rate. In the temperature range studied, NO2 decomposes to N2 and O2.

Improved process for the further processing of hydrogen sulphide-containing gases

Abstract: A process for treating H2S-containing gases which have also a relatively high CO2 content, wherein sulphur-containing compounds of said gases are converted to elemental sulphur in a Claus plant. The process is applied to gases having a calculated H2S/CO2 ratio of less than 1. In a first absorption zone (2a, 2b) sulphur-containing compounds (H2S, COS, CS2) and C02 are absorbed in a liquid under non-selective absorption conditions, and after regeneration of said absorption liquid, partly fed to a Claus plan (10) and partly to a catalytic reduction zone (17). The off-gas of the Claus plant is also introduced in said reduction zone wherein any sulphur compounds other than H2S are converted into H2S in the presence of H2 and/or CO. The gas mixture leaving the reduction zone is treated for H2S removal in a second absorption zone (20) with the same liquid as applied in said first zone under conditions which are selective in respect of co-absorption of CO2. The H2S-containing absorption liquid of said second zone is regenerated in a regeneration zone (7) common to the first and second absorption zone, whereby the calculated H2S/CO2 ratio of the feed to the Claus plant is improved.

Preparation of intermediate for pigment

Abstract: PURPOSE:To obtain 6-chloro-3-amino-toluenesulfonic acid-(4) or its salts which are intermediates for pigments, by catalytic reduction of 6-chloro-3-nitrotoluenesulfonic acid or its salts using a platinum catalyst in an aqueous solvent.

Preparation of 44 piperidinopyridine

Abstract: PURPOSE:To prepare the title compound useful as an intermediate of pesticide and medicine, and catalyst, economically, by the catalytic reduction of N-(4-pyridyl)pyridinium salt (easily derived from pyridine) with H2 in an alcohol, in the presence of Pd catalyst, under mild conditions. CONSTITUTION:4-Piperidinopyridine of formula II is prepared by reducing a hydrogen halide salt of N-(4-pyridyl)- pyridinium salt of formula I (X is halogen) in an alcohol such as methanol, ethanol, etc., in the presence of Pd catalyst, such as palladium oxide, Pd/C catalyst, etc., at O-40 deg.C and 1-5 kg/cm (pref. at room temp. and normal pressure).

Activation of catalyst

Abstract: PURPOSE:To reactivate poisoned catalyst simply in a short time as well as enhance catalytic activity of unused catalyst by exposure of metal oxide catalysts-carrying porous support to supersonic wave in water or a diluted inorganic acid aequeous solution. CONSTITUTION:A catalyst consisting of a metal oxide supported by a porous support, e.g., silica, alumina, titania, etc., particularly the catalyst for the catalytic reduction of NOx present in gases, is exposed, prior to use or after being deactivated by use, to supersonic wave for a short time in water or a 0.03 to 1.3 wt% inorganic acid aqueous solution, washed with water, and then dried in order to increase or reactivate the catalytic activity of the catalyst. The preferred frequency of the supersonic wave irradiated is approx. 15 to 40 kHz, and also the preferred output of the oscillator is more than 0.35 W/cm . And, the application of a greater amplitude of supersonic wave is more effective. When the catalyst exposed to supersonic wave is washed with water sufficiently, dried at 100 to 150 deg.C, for example, for approx. 1 hour, treated by heating at approx. 400 to 650 deg.C, and lastly baked for 30-180 min. much higher reactivation effect can be attained.

Method and apparatus for removing nitrogen oxides in exhaust gas

Abstract: PURPOSE:To efficiently remove NOx in combustion exhaust gas by gasifying a solid granular or powder material of sublimability and gasifiability as a reducing agent and supplying the gasified material to the exhaust gas. CONSTITUTION:When NOx are directly reacted with a reducing agent such as urea at high temp. in the absence of catalyst, combustion exhaust gas 1 is introduced into urea evaporator 2 and solid urea 3 is gasified by heating. Gas 1 is then fed to reactor 4 kept at high temp. together with gaseous urea molecules to carry out denitration, and the denitrated gas is introduced into exhaust line 5. At this time, the urea is gasified at 100-420 deg.C and injected into the exhaust gas. In case of catalytic reduction using catalyst, gas 1 is introduced into evaporator 2 and urea 3 is gasified by heating. Gas 1 is then fed to catalyst-packed reactor 6 together with gaseous urea molecules to complete denitration, and the denitrated gas is introduced into line 5. By these methods, NOx in exhaust gas can be removed at reduced construction and operational costs.

Preparation of oochloroaniline

Abstract: PURPOSE:To prepare o-chloroaniline, in high selectivity and yield, using a low-cost reactor, and without causing environmental pollution, by the catalytic reduction of o-chloronitrobenzene in the presence of NH3 and water, using an extremely small amount of Pt-C catalyst, under a mild reaction condition. CONSTITUTION:o-Chloroaniline is prepared with a selectivity of >=99.9% and a purity of >=99.8% by the hydrogenation of o-chloronitrobenzene in the presence of NH3 and water, using a Pt-C catalyst, at 45-137 deg.C under a hydrogen pressure of 5-30 kg/cm . The Pt-C catalyst is the one prepared by conventional process, and its amount is as low as 0.01-0.03 wt% based on the raw material. The supported amount of the catalst is 1-5%. The amounts of NH3 and water are 0.35- 1.98 wt%, and 1-50 wt%, based on the raw material, respectively. Use of larger amount of water remarkably improves the reaction rate, and further decreases the amount of the catalyst.

Denitrating method by catalytic reduction with ammonia

Abstract: PURPOSE:To increase reduction denitration performance described in the title, by addn. of alcohol or aldehyde to an exhaust gas contg. NOx principally composed of NO so as to bring it into contact with the NOx in the presence of NH3. CONSTITUTION:Alcohol or aldehyde is added to an exhaust gas contg. NOx principally composed of NO at an exhaust gas temp. 450-600 deg.C. in the molar ratio of the alcohol or aldehyde to the NO of 0.1-10. The NO is oxidized with the alcohol or aldehyde to a molar ratio of NO2/NOx of 0.3-0.7 at the inlet of catalyst layer. The maximum denitration ratio of catalytic reduction denitration with NH3 is obtained at the molar ratio NO2/NOx of 0.5. NH3 is added at a gas temp. 300- 600 deg.C, and the gas is allowed to reach the catalytic layer in 0.1 sec. or more after the addn. of alcohol or aldehyde.

Priduction of 22chloroo55aminotoluenee44sulfonic acid or its salt

Abstract: PURPOSE:The catalytic reduction of 2-chloro-5-nitrotoluene-4-sulfonic acid is effected in the presence of a Raney-nickel catalyst to produce high-purity title compound useful for an intermediate of azo dyes and organic pigments as lakered C in high yield. CONSTITUTION:The catalytic reduction of 2-chloro-5-nitrotoluene-4-sulfonic acid or its salt is carried out in the presence of a catalyst that is prepared by soaking a nickel-aluminum alloy in an alkali metal hydrxide aqueous solution to dissolve the aluminum in an aqueous solution or dispersion to produce 2-chloro-5-aminotoluene- 4-sulfonic acid or its salt. The reaction temperature is preferably 20 - 100 deg.C. EFFECT:Wastes difficult to be deposited does not form and the reaction can be economically effected under mild conditions in a short time.

Removing method for nox contained in exhaust gas

Abstract: PURPOSE:To denitrate exhaust gas with remarkably reduced caralyst cost, at a relatively low temp. so as to decrease energy cost, by catalytic reduction of NOx contained in the exhaust gas by use of manganese ore as a catalyst in the presence of NH3. CONSTITUTION:Exhaust gas contg. NOx is denitrated by addn. of NH3, using manganese ore as catalyst, which has been broken to a suitable particle size and made even-sized, or calcined in addn., in order to reduce catalytically NOx to NO. Inexpensive manganese ore exhibits excellent denitrating performance as catalyst at a low temp. of 200 deg.C. The manganese ore with decreased catalytic activity after use can be used as it is as raw material for producing ferroalloy or dry cells. Catalyst used in this method contains gibbsite, todorokite, or pyrolsite, which are broken to 3.3-7.9mm. and made uniformsized, as principal components.

Kinetic studies on the catalytic reduction of nitrotoluene by hydrazine

Abstract: Kinetics of reduction of p-nitrotoluene by hydrazine in presence of Raney nickel catalyst have been studied spectrophotometrically. It has been found that the reaction is first order with respect t...

Denitrating method by reduction with ammonia

Abstract: PURPOSE:To restrain the effluent of NH3, to increase denitration ratio, and to reduce equipment cost, by, in denitration of exhaust gas, addn. of NH3 and H2O2 to the exhaust gas which is at a specific temp. range, then by passing the exhaust gas additionally through a layer of metallic oxide catalyst. CONSTITUTION:To exhaust gas 12 (at a temp. not lower than 400 deg.C) discharged from a turbine are added NH3 14 (in a mol ratio 0.5-3 to NOx) from nozzles 7, and H2O2 15 (in a mol ratio 0.3-1 to NH3) from nozzles 8 in order to decompose NOx contained in the exhaust gas in gas phase. By passing the exhaust gas through a conventional metallic oxide catalyst layer 9 (at a temp. 600-250 deg.C), residual NOx is reduced catalytically with unreacted NH3 so as to complete the denitration. In that case, because nearly all NO has been oxidized to NO2, and the rate of reaction of NO2 with NH3 is larger than that of NO, the catalyst layer of smaller volume is sufficient to complete the reaction. In addn., combination of gas phase reduction with N2O2 and NH3 and catalytic reduction shows synergetic effect, restraining effluent of NH3 and increasing denitration ratio.

Method and apparatus for denitrating exhaust gas

Abstract: PURPOSE:To denitrate the exhaust gas with a good controllability at an optional low temperature without using the catalyst, by exciting nitrogen compounds and the reducing substance using the corona discharge and making these compounds react with each other, at the dry catalytic reduction process using ammonia.

Method and apparatus for dry catalytic reduction of nitrogen oxide contained in exhaust combustion gas

Abstract: PURPOSE:To reduce NOx surely at a low cost by specifying O2 and CO concns. of a mixed gas of blast furnace (or converter) exhaust gas with smelting exhaust gas which contains CO as a reducing agent. CONSTITUTION:While being sent through a flue 2 to a denitrating catalyst layer 10, exhaust combustion gas from its originating source 1 is mixed with smelting exhaust gas, which is added through a nozzle 8 and contains CO as a reducing agent. An O2-concn. analyzer 3, a combustion control unit 4, a flow meter 5b and a flow control unit 5 for exhaust smelting gas, and a flow control valve 5a are adjusted respectively so as to maintain the O2 concn. of the mixed gas at 3% or below, and to made the relative ratio CO to O2 satisfy the following equation: CO%>=O2% x2+1%.

Removing method for nitrogen oxides

Abstract: PURPOSE:To save fuel consumption for heating and to denitrate exhaust combutsion gas efficiently, by addn. of hydrocarbon fuel to the exhaust gas before it is fed to a reactor so as to oxidize the hydrocarbon catalytically and to reduce and remove NOx with NH3. CONSTITUTION:After starting operation of denitration apparatus consisting of a multitubular heat-exchanger 1, a heating-up furnace 2, a mixer 3, and a reactor 4, when the temp. at the outlet of the reactor is raised up to 200-400 deg.C, the heating-up furnace 2 is shut down, and simultaneously hydrocabon fuel, e.g., LPG, is added to the exhaust gas at the inlet side of the mixer 3, then the reaction temp. in the reactor 4 is maintained at 200-400 deg.C, by the catalytic oxidation of LPG caused by iron ore, a denitration catalyst, thus catalytic reduction of NOx with NH3 proceeding efficiently. Becuase the hydrocarbon fuel is oxidized catalytically without use of combustion air unlike the heating-up furnace 2, temp. rise of the exhaust gas is very small and heat energy consumption is reduced remarkably.

The effects of supports on the reaction of no with nh3 catalyzed by v2o5

Abstract: The reaction mechanism of the catalytic reduction of NO by NH3 was studied using V2O5–Al2O3 and V2O5–SiO2 catalysts. On V2O5–Al2O3the reaction rate was enhanced by the presence of oxygen and the reaction was found to proceed through the formation of NO2 adsorbed on the catalyst surface. While on V2O5–SiO2 no effects of oxygen were observed and the reaction seems to proceed through the formation of HNO adsorbed on the catalyst, since N2O, which may be produced by the decomposition of HNO adsorbed, was detected during the reaction.