Showing papers on "Selective catalytic reduction published in 1982"

Simultaneous sulfur oxide and nitrogen oxide control in FCC units using cracking catalyst fines with ammonia injection

Abstract: Sulfur oxide and nitrogen oxide control by use of a sulfur sorbent and sulfur dioxide oxidation promoter in the regenerator and downstream removal of nitrogen oxides by selective catalytic reduction using ammonia injection and trapped cracking catalyst fines

Process for synthesizing urea

Abstract: In a synthesis of urea using ammonia in a highly excessive molar ratio, unreacted materials are decomposed and separated by subjecting the urea synthesis effluent to a stripping step using carbon dioxide at a pressure equal to the urea synthesis pressure. The thus-separated gaseous mixture of ammonia and carbon dioxide is condensed through an indirect heat exchange with an effluent stream discharged from the stripping step and lowered to a predetermined pressure level. Resulting condensation heat is used for the decomposition and separation of unreacted materials still remaining in said effluent stream. By choosing suitable operation conditions for each step of the present invention, it is possible to reduce the amount of high pressure steam to be required and to minimize the amount of low pressure steam to be recovered.

Selected conversion of NOx by catalytic reduction with ammonia. An effective off-gas treatment system is an environmental must in the reprocessing of nuclear fuels. An up-to-date progress report

Abstract: The General Atomic Company off-gas treatment system is designed to process simulated radioactive or other noxious volatile and gaseous constituents in dissolver off-gas (DOG) streams indigenous to several nuclear fuel cycles, e.g., light-water reactors (LWRs). A series of NO/sub x/ converter tests was carried out with the GA engineering-scale system. The major reactions and optimum conditions were characterized for the selective catalytic reduction of pure NO, pure NO/sub 2/, and NO/sub x/ with NH/sub 3/ over synthetic hydrogen mordenite (Zeolon 900 H). Steady-state conversions in the range 99 to 99.9% were obtained for the specified conditions without observing any breakthrough of NH/sub 3/ in the effluent. The NO/sub x/ reduction capacity for a single-stage adiabatic converter is approximately 1% NO/sub x/ in the feed gas and is restricted by catalyst temperature limitations. 7 references, 9 figures. (JMT)

Method for removal of nitrogen oxide

Abstract: PURPOSE:To obtain a catalyst of high heat resistance having sufficient activity at elevated temp over a long period of time in performing catalytic reduction of NOX in the presence of NH3 by forming the carrier of catalysts of composite oxides contg P as a constituting element CONSTITUTION:This catalyst contains both components of A) >=1 kinds of 3- or 4-element composite oxides consisting of Ti, P, Si and/or Zr, and B) oxides of >=1 kinds of W, Ce, Sn Here, the component A per se has activity for the NOX in waste gases, and also plays the role of a carrier This is a solid acid and exhibits marked acidity not observed in respective independent oxides, and has high heat resistance coupled with high specific surface area With the P in the component A, various effects can be observed; above all, it suppresses particularly the oxidation of NH3 to NOX and the crystallization of catalyst components As a result, it maintains high activity for a long period of time

Support effects on iron(III) oxide catalyst in the reduction of nitrogen oxide with hydrogen

Abstract: Catalytic reduction of NO with H2 has been carried out over Fe2O3 dispersed on ten kinds of supports. Among the carrier oxides, Fe2O3 on SiO2 was the most effective catalyst and Fe2O3 on SnO2 was least active. The surface states and adsorption states of NO on supported Fe2O2 were studied by means of i.r. and Mossbauer spectroscopies. The intensities of the i.r. bands at 1810 and 1735 cm-1 of the adsorbed NO on reduced iron sites are discussed in connection with the catalytic activity.

Exhaust gas catalyst

Abstract: An exhaust gas catalyst for treatment of exhaust gases developed by burning a hydrocarbon fuel or a fuel containing hydrocarbon and alcohol blends In an internal combustion engine comprises a support having deposited thereon palladium and finely divided tungsten. The palladium/tungsten combination is effective in the catalytic oxidation of unburned hydrocarbons and carbon monoxide and the catalytic reduction of oxides of nitrogen without production of significant amounts of ammonia when the internal combustion engine is operating under fuel rich conditions. In one embodiment the palladium and tungsten are both distributed over the whole of the support; in another embodiment the palladium is distributed over the whole of the support and the tungsten only over a downstream portion thereof; in a third embodiment the palladium is distributed over an upstream portion of the support and the tungsten over a downstream portion thereof.

Process for the preparation of hydroxylammonium salts

Abstract: Process for the preparation of hydroxyl ammonium sulphate by catalytic reduction of nitrogen monoxide with hydrogen in aqueous sulphuric acid in the presence of suspended supported platinum catalysts at elevated temperature, characterised in that during the reaction the concentration of free sulphuric acid from 0.3 N to 3.0 N is maintained and that at the end of the reaction the content of free sulphuric acid is allowed to drop.

Process for methane synthesis by catalytic reduction of carbon monoxide in aqueous phase

Abstract: Process for the catalytic synthesis of methane by reaction of carbon oxides with hydrogen in the presence of liquid water, wherein the catalyst is formed of a carrier consisting either of coal or charcoal, preferably of plant origin, or of alumina-silica, on which is deposited ruthenium, for example by impregnation with ruthenium acetylacetonate, said catalyst being preferably used as particles suspended in water.

Catalytic thermal cracking catalyst of nitrogen dioxide

Abstract: PURPOSE:To obtain a catalyst applicable to a catalytically reductive denitration method of ammonia for suppressing N2O as a byproduct, by constituting the same from one prepared by supporting oxide of one or more of a metal element selected from Mn, Co, Cr and Cu by a carrier. CONSTITUTION:The titled catalyst is constituted of one prepared by supporting oxide of one or more of a metal element selected from a group comprising Mn, Co, Cr and Cu by a carrier. Powders comprising oxides of these metal elements are mixed in a dry or a wet system and the resulting mixture is dried, molded and baked to obtain an objective catalyst. Thus obtained catalyst can preliminarily convert NO2 contained in exhaust gas to NO in good efficiency in a denitration process due to catalytic reduction for ammonia and, as the result, the generation of N2O as a byproduct in denitration reaction is suppressed and a denitration process for NO2-containing gas can be realized in a high denitration ratio.

Novel transetherification in catalytic reduction of 4-alkoxynitrobenzenes in alcohol-sulfuric acid solution

Abstract: In catalytic reduction (5% Pt–C, 1 atm H2) of 4-alkoxynitrobenzenes (R1O–C6H4–NO2) in alcohol(R2 OH)-sulfuric acid solution at room temperature, the reduction was found to be accompanied by transetherification to afford R2O–C6H4–NH2.

Denitration method of gas containing nox

Abstract: PURPOSE:To denitrate efficiently NO2 in NOx-contg. gas without by-producing N2O by reducing at least a part of NO2 in said gas to NO then subjecting the same to a denitration treatment by an ammonia catalytic reduction method. CONSTITUTION:The NOx-contg. gas which contains the NO2 introduced through a line 1 is heated to a prescribed temp. with a heater 5 and is then introduced into an NO2-NO converter 6. The above-mentioned gas is brought into contact with a catalyst 9 contg. the oxide of metal such as Co as an active component in said converter, so that at least a part of NO2 is reduced by a reducing agent such as H2 and is converted to NO, thereby decreasing the ratio of NO2 in the NOx to more preferably <=50%. NH3 is added to said gas through a line 7 and the gas is introduced into a denitration reactor 8. The gas is brought into contact with a catalyst 10 combined with the oxides of Ti, V, Mo and W in said reactor and NO2 is denitrated with high efficiency by reduction reaction.

Process for eliminating di-nitrogen oxide from exhaust gases

Abstract: A process for removing nitrous oxide from soiches containing exhaust gases, which have been obtained in the preparation of hydroxylammonium salts by catalytic reduction of nitric oxide with hydrogen in aqueous solutions of mineral acids in the presence of suspended noble metal catalysts, wherein the exhaust gases are washed with water.

Operation of denitration apparatus

Abstract: PURPOSE:To rapidly remove the reaction products of SOX and NH3, crystallized on catalyst at low temperatures, by controlling the amount of NH3 to inject to less than an equimolar amount on the basis of NOX present in waste gas in a NH3 catalytic reduction type denitration method. CONSTITUTION:Waste gas containing SOx is treated at 300 deg.C or lower in an NH3 catalytic reduction type denitration apparatus, where SOX is reacted with NH3 injected as a reducing agent to crystallize the reaction products of SOX and NH3 on a catalyst, whereby lowering the activity of the catalyst. When the activity of the catalyst is lowered, the injection of NH3 to the apparatus is temporarily stopped or the amount of NH3 to inject is controlled to less than an equimolar amount on the basis of NOX present in waste gas. Thus, NH3 present in the reaction products of SOX and NH3, deposited inside the pores of the catalyst, is selectively and rapidly reacted with NOX in the waste gas and the NOX is therefore decomposed into N2 and sulfuric acid and removed.

Method for treating exhaust gases with an improved catalyst composition

Abstract: There is disclosed a method of using an exhaust gas catalyst for treatment of exhaust gases developed by burning a hydrocarbon fuel or a fuel containing hydrocarbon and alcohol blends in an internal combustion engine. These exhaust gases contain varying amounts of unburned hydrocarbons, carbon monoxide and oxides of nitrogen depending upon the operating conditions of an internal combustion engine. This specification teaches a method of using an improved catalyst composition in which a support medium is provided for supporting the catalyst system. This support medium has deposited thereon palladium and finely divided tungsten. Tungsten is present on the support media in a quantity such that tungsten is available to substantially all of the palladium on the support medium. In this manner, the palladium/tungsten combination is effective in the catalytic oxidation of unburned hydrocarbons and carbon monoxide and the catalytic reduction of oxides of nitrogen without production of significant amounts of ammonia when the internal combustion engine is operating under fuel rich conditions.

Palladium catalyst promoted by tungsten

Abstract: OF THE DISCLOSURE There is disclosed a method of using an exhaust gas catalyst for treatment of exhaust gases developed by burning a hydrocarbon fuel or a fuel containing hydrocarbon and alcohol blends in an internal combustion engine. These exhaust gases contain varying amounts of unburned hydrocarbons, carbon monoxide and oxides of nitrogen depending upon the operating conditions of an internal combustion engine. This specification teaches a method of using an improved catalyst composition in which a support medium is provided for supporting the catalyst system. This support medium has deposited thereon palladium and finely divided tungsten. Tungsten is present on the support media in a quantity such that tungsten is available to substantially all of the palladium on the support medium. In this manner, the palladium/tungsten combination is effective in the catalytic oxidation of unburned hydrocarbons and carbon monoxide and the catalytic reduction of oxides of nitrogen without production of significant amounts of ammonia when the internal combustion engine is operating under fuel rich conditions.

Review of Japanese Nox Control Technology for Stationary Sources

Abstract: ABSTRUCT In Japan, combustion modification (CM) to reduce 20–70% of NO X has been applied to about 100,000 stationary sources. NO X concentrations in flue gases from utility boilers have been lowered by CM to 150–400 ppm for coal, 80–130 ppm for oil, and 40–80 ppm for gas. For further abatement, about 140 selective catalytic reduction (SCR) plants have been constructed to remove 50–90% of NO X in flue gases. The cost of SCR is higher than that of CM but is about one-fifth to one-third that of flue gas desulfurization (FGD). For coal-fired boilers, the combined SCR-FGD process has been applied. The power generation cost with coal and the combined cleaning process is less than that with low-sulfur oil to give about equal quality of stack gas. The success of the cleaning process has promoted the construction of coal-fired boilers and contributed significantly to save oil and to solve the energy problems. Simultaneous SO X and NO X removal processes such as activated carbon and electron beam processes as well as fluidized bed combustion of coal have been tested. By those efforts along with the stringent control of automobile exhausts and reduction of hydrocarbon emissions, photochemical smog problems have been considerably reduced.

Process for preparing saturated ω-amino acids

Abstract: A process for continuous or batch preparation of an ω-amino-acid is scribed, 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 ω-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 ω-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.

The Hitachi Zosen NO /SUB x/ removal process for fossil fueled boilers

Abstract: Nitrogen oxides in the atmosphere have been determined to have adverse effects on human health and welfare. Over 95 percent of man-made NO /SUB x/ emission results from combustion processes. Nitrogen and oxygen can combine to form several nitrogen oxide compounds. However, for most combustion processes, the only nitrogen oxide compounds produced in significant concentrations are nitrogen oxide (NO) and nitrogen dioxide (NO/sub 2/). Typically, NO represents 90 to 95 percent of the NO /SUB x/ emissions from combustion. But this NO gradually oxidizes to NO/sub 2/ once it is exposed to oxygen in the atmosphere. There are three methods available to control NO /SUB x/ emissions. Pre-combustion control is primarily limited to switching the type of fuel burned in order to reduce the quantity of fuel bound nitrogen and thus NO /SUB x/ emissions. Combustion modification involves careful control of the temperature and the oxygen available in the combustion zone. This method of control is relatively well developed technology, and it is relatively inexpensive. However, the NO /SUB x/ removal efficiency associated with combustion modifications is limited to about 50 percent. Flue gas treatment is the third method of controlling NO /SUB x/ emissions. NO /SUB x/ removal efficienciesmore » greater than 80 percent are possible and selective catalytic reduction (SCR) processes are capable of over 90 percent reduction in NO /SUB x/ emmissions.« less

Process for urea synthesis

Abstract: An inert gas which contains carbon dioxide and ammonia separated from a urea synthesis off-stream under urea synthesis pressures is brought into contact with an absorbent together with unreacted carbon dioxide and ammonia which were separated in the high-pressure distillation at a gauge pressure of 10 to 25 kg/cm , to absorb essentially all the carbon dioxide and the predominant proportion of the ammonia, and cooled to separate the liquid ammonia obtained and then removed The inert gas can be treated by the above method with little or no risk of explosion

Continuous manufacture of hydroxyl ammonium

Abstract: An improved process for the continuous preparation of hydroxylammonium salts by catalytic reduction of nitric oxide with hydrogen in a dilute aqueous solution of a mineral acid in the presence of a suspended noble metal catalyst at an elevated temperature in several reaction zones connected in series, wherein the improvement comprises maintaining a pH of <20 in the last reaction zone