Showing papers on "Selective catalytic reduction published in 1980"

Electrocatalytic reduction of carbon dioxide by using macrocycles of nickel and cobalt

Abstract: An indirect method for the reduction of CO/sub 2/ in nonaqueous solutions and involving initial reduction of metal complexes and their subsequent reduction with CO/sub 2/ is described. The complexes were tetraazamacrocyclic complexes of Ni and Co. The catalytic reduction process was investigated by means of controlled potential coulometry experiments performed in a gas-tight electrolysis cell under a CO/sub 2/ atmosphere. The effects of water, Ar, and N/sub 2/ on the electrolysis process were investigated. The results indicated that the indirect electrochemical reduction of CO/sub 2/ occurred at a potential between -1.3 and -1.6V vs SCE and that the reduction was indeed catalyzed by the metal complexes. Reaction periods of as long as 24 h did not reduce catalytic activity; and in most cases, the catalyst was isolated in its original form at the end of the run. A protic source was found to be necessary for the reaction to yield CO and H/sub 2/; and in the absence of a protic source, simple stoichiometric reduction of the complex was noted. (BLM)

Filter house having catalytic filter bags for simultaneously removing NOx and particulate matter from a gas stream

Abstract: A filter house (12) employing a selective catalytic reduction process for removing NO x emissions from a flue gas stream while simultaneously filtering out and collecting entrained particulate matter from the stream. Accordingly, the filter house (12) includes flue gas inlet and outlet passages (18, 30) and a plurality of porous filter bags. The bags are treated with a suitable catalyst to facilitate the selective catalytic reduction process.

Process for controlling nitrogen oxides in exhaust gases and apparatus therefor

Abstract: In a process and an apparatus for controlling oxides of nitrogen in exhaust gases from combustion equipment by decomposing the oxides, in the presence of oxygen, with ammonia blown into the equipment and associated ducting at temperatures within the range from 700° to 1300° C., a catalyst assembly is arranged, with the catalytic surfaces of the component units substantially in parallel to the direction of exhaust gas flow, in a region where the temperature of the gas after the decomposing treatment is between 300° and 500° C., and the gas after the decomposing treatment is caused to pass through the catalyst assembly to decompose residual nitrogen oxides and ammonia in the gas to innocuous substances. An additional supply of ammonia, in an amount from 0.5 to 1.5 times equivalent (in molar ratio) to the amount of nitrogen oxides in moles in the gas is introduced into the space immediately upstream of the catalyst assembly, thereby to accelerate the decomposition of the oxides in the gas to make it harmless.

Catalyst for selectively reducing nitrogen oxides from oxygen-containing exhaust gases

Abstract: A catalyst for selective catalytic reduction of nitrogen oxides by use of ammonia as a reducing agent is prepared by mixing a silicic acid material with a lime material, heating the mixture under pressure to form a slurry of calcium silicate crystals, forming the slurry into a carrier, and then allowing the carrier to carry a catalytically active ingredient.

Flexible integrated method for the production of ammonia and urea

Abstract: In an integrated flexible installation for producing ammonia and urea, the improved method which consists in that a portion of the gaseous stream comprising carbon dioxide, hydrogen and nitrogen is fed to a complementary decarbonation area and then admixed with a portion of a similar, but non-decarbonated stream of gas prior to entering the carbon-dioxide-absorption unit. Liquid ammonia is recovered from a portion of the ammoniated aqueous solution used for abating the ammonia and sent to a distillation column to recover liquid ammonia therefrom.

Removal of nitrogen oxides and sulfur oxides by ammonia

Abstract: When exhaust gas from a coal-burning boiler containing NOx as well as SOx is subjected to NOx removal by catalytic reduction of the NOx with ammonia and the coal ashes contained in the gas are separated, the coal ashes are contaminated by a certain quantity of ammonium compounds produced from the SOx and the ammonia excessively used The ammonium compounds in the coal ashes are decomposed into ammonia and a sulfur compound by heating by the hot gas at a temperature in the restricted range, viz 350° to 700° C, thereby to release ammonia into the gas preferentially to the sulfur compound The ammonia thus released is recycled to the NOx removal step

Fundamental Studies on the Catalytic Removal of Nitrogen Monoxide using Reducing Agents

Abstract: The behavior of adsorbed nitrogen monoxide (NO) and the reactivity of NO with reducing agents were investigated. Two species with N-O stretching frequencies at 1, 790 and 1, 850 cm-1, respectively, were found from the infrared studies of adsorbed NO on a cobalt-silica catalyst. The former arose from the strongly chemisorbed species and it was the intermediate species in the reaction between NO and reduced surface. Bases such as NH3, NH2CH3, NH (CH3)2 and N(CH3)3 resulted in the lowering of the N-O stretching frequencies of preadsorbed NO, indicating weakening of the N-O bond. This was explained on the basis of a change in the electron density of metal-N-O molecular orbitals when a second gas was admitted.The roles of reducing agents such as H2, CO and NH3 in the catalytic reduction of NO over supported metal or metal oxide catalysts were studied from the viewpoint of reaction mechanism. The reaction of NO with H2 or CO was shown to proceed through a redox cycle of the catalyst, that is, the catalyst was oxidized by NO and then it was reduced by the reducing agents to complete the catalytic sequence. On the other hand, it was confirmed by means of isotope labelling techniques that NH3 or fragments of NH3 directly reacted with the adsorbed NO. Also, the reaction of NO with NH3 was greatly enhanced by preoxidation of a Cr2O3-Al2O3 catalyst and this effect was due to the oxygen with a high oxidation power which was produced on the catalyst surface.These differences in the roles of reducing agents in the reaction mechanism satisfactorily explain some aspects of catalytic removal of NO in the practical process where oxygen is present.

Catalytic reduction of dinitroaromatic compounds with hydrogen sulphide–carbon monoxide. A novel, low-cost replacement for elemental hydrogen

Abstract: A mixed reducing gas consisting of H2S and CO, when used with sulphided Fe on Al2O3 heterogeneous catalysts, has successfully reduced dinitroaromatic to diaminoaromatic compounds in high yield and conversion.

Catalytic reduction of co2 to co using sulfur vapor as a reducing reagent

Abstract: The catalytic reduction of CO2 to CO by sulfur vapor was studied at the temperatures higher than 650°C over various metal oxides and sulfides, and on the basis of the results from the kinetic studies and the X-ray diffraction measurements, the reaction scheme was tentatively proposed as follows: metal oxides + S2(g) → metal sulfides + SO2 metal sulfides + CO2 → metal oxides + CO + SO2.

Catalyst mixture for the catalytic reduction of nitrogen oxides in gaseous mixtures

Abstract: A physical mixture of a first and second catalyst. 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.

Preparation of phenylethylamine

Abstract: PURPOSE:To obtain the title compound, an intermediate for organic synthesis, economically, by extracting impurities, formed through catalytic reduction of acetophenone in the presence of a nickel catalyst, ammonia, and methanol, with a water- insoluble solvent instead of steam distillation readily. CONSTITUTION:Acetophenone (A)is catalytically reduced in the presence of a nickel catalyst, e.g. Raney nickel or reduced nickel, ammonia, and methanol at 50-150 deg.C, preferably 70-120 deg.C, and 2-150kg/cm , preferably 5-130kg/cm . A mineral acid is added to the reaction mixture to give an aqueous salt of alpha- phenylethylamine, and impurities forming no salts are extracted and eliminated from the solution with 3-400% based on A of an organic water-insoluble solvent, e.g. benzene or toluene, to give the title compound.

Continuous operation method of exhaust gas denitration process

Abstract: PURPOSE:To continuously operate this process over a long period while fixedly keeping the desired denitration coefficient continually, in an operation method of this exhaust gas denitration process for making notrogen oxides in exhaust gas harmless by means of an ammonia catalytic reduction method. CONSTITUTION:This process is operated in order to reduction remove notrogen oxides in such a manner that ammonia from an ammonia supply source U is introduced to an exhaust gas drawing line alpha joining a generating source P of exhaust gas, in which the concentration of nitrogen oxides contained, the quantity of gas generated and/or the temperature of gas generated change, and an exhaust gas denitration device Q through a control valve a4 controlled in response to the output of a computing element a3, to which signals from a nitrogen oxide concentration measuring meter a1, an exhaust gas flow-rate measuring meter a2, an exhaust gas temperature meansuring meter a5, etc. are input, and a line omega. When no reaching to the desired denitration coefficient is detected by means of a measuring meter Z in a discharge line beta, an IN-LINE heater R is operated, and catalysts, which lose their activity, in the denitration device Q are regenerated.

Catalytic reduction of nitro aromatic compounds with hydrogen sulfide and carbon monoxide

Abstract: In the reduction of di- or polynitro aromatic compounds by gaseous H 2 S over a solid catalyst, addition of CO gas promotes formation of amino groups from all nitro groups in the molecule. A preferred embodiment is reduction of 2,4- and/or 2,6-dinitrotoluene in vapor phase at 325° C. over a supported iron or supported cobalt catalyst on a support comprising alumina. The amino products are useful for production of polyurethane resins.

Method for removing nitrogen oxide in waste gas and catalyst therefor

Abstract: PURPOSE:To obtain a high performance catalyst having a high heat resistance as a reductive catalyst for nitrogen oxides present in waste gas by supporting a tungsten oxide, etc., on a coprecipitated alumina-titania support. CONSTITUTION:As a catalyst used in the catalytic reduction removal of nitrogen oxides present in waste gas by using ammonia as a reducing agent, tungsten oxide alone or a combination of tungsten oxide and 5wt% or less cerium oxide is supported on a support obtained by coprecipitation of an aqueous solution of containing an ammonium salt and a titanium salt with an alkali. The catalyst thus obtained is excellent in heat resistance in a temperature region of 400-700 deg.C as well as in catalytic performance and also is inexpensive.

Preparation of 4-substituted indole

Abstract: PURPOSE: To obtain a 4-substituted indole useful as a raw material for a medicine or an agricultural chemical industrially and advantagenously, by reducing a β- dimethylaminostyrene derivative in the presence of a solvent. CONSTITUTION: A β-dimethylaminostyrene derivative of formula I (R 1 is 1W4C alkyl, acetyl or benzyl) is reduced with preferably titanium trichloride as a reducing agent in the presence of a solvent to give a 4-substituted indole of formula II. The raw material compound of formula I is obtained readily in high yield by reacting an o-nitrotoluene derivative of formula III with N,N-dimethyformamide dimethyl acetal. A compound of formula IV in formula II can be readily converted into 4-hydroxyindole by the catalytic reduction, and the compound is useful as a raw material for pindolol useful as an antiarrhythmic agent or hypotensive agent. COPYRIGHT: (C)1982,JPO&Japio

Novel cyclohexylacetic acid derivative

Abstract: NEW MATERIAL:A cyclohexylacetic acid derivative of formula I (R are H, lower alkyl; R is 2-6C straight or branched chain alkyl). EXAMPLE:alpha-Methyl-(4-isobutylcyclohexyl)acetic acid. USE:Medicine having antiphlogistic, antithrombotic, antiallergic, and immunoinhibiting activities. PROCESS:The compound I is prepared by the catalytic reduction of a compound II (prepared by the method similar to those disclosed in the Japanese patent publication No.40-7178, 40-7491, etc.) in the presence of a catalyst such as platinum dioxide, etc.

Catalytic reduction of 2-nitronaphthalene-4,8-disulfonic acid ammonium salt

Abstract: 2-Naphthylamine-4,8-disulphonic acid is produced by catalytically hydrogenating the ammonium salt of 2-nitronaphthalene-4,8-disulphonic acid using Pt/C or Pd/C as the catalyst.

Process for preparing saturated omega-amino acids

Abstract: A B S T R A C T A process for continuous or batch preparation of an .omega.-amino-acid is described, comprising the imination of an unsaturated aldehyde acid, the catalytic reduction in a single hydrogenation step of the imine of the ethylenically unsaturated straight chain .omega.-aldehyde acid in the presence of ammonia and an alkaline metal hydroxide whereby the alkaline salt of the imine is obtained, and the acidification of the alkaline salt of the .omega.-amino acid. The imine of formyl alkenoic acid is prepared at most at room temperature adding the acid to an ammonia solution of above 10%, then adding NaOH solution to the ammonia solution The reductive imination is effectuated in two steps, first at 100-150°C and the second at 150-180°C under a 20-70 Ate pressure in the presence of a nickel catalyst. High yield and only few by-products are obtained.