Abstract: Reticulated ceramic or metal substrate coated with Cobalt compounds, noble metals or mixtures thereof are superior catalysts for the oxidation of ammonia to produce nitric oxide.

Abstract: The present invention relates to a method of reduction of nitrogen oxides in gas mixtures, especially the removal/decomposition of nitrogen oxide in hot combustion gases. The hot gas mixture which contains N.sub.2 O is given a retention time of 0.1-3 seconds before being cooled down. About 90% of N.sub.2 O is thereby decomposed to N.sub.2 and O.sub.2. A hot gas mixture formed by catalytic combustion of ammonia is given a retention time of 0.5-2 seconds before it is cooled in a heat recovery unit. The combustion gases can also be brought in contact with a metal or metal oxide catalyst for selective decomposition of the N.sub.2 O.

Abstract: A process for the generation of mechanical energy in the ammonia oxidation step of process for the production of nitric acid is disclosed, whereby the utilization of process heat is improved, particularly the exploitation of heat contained in NO.sub.x gases and including process heat recovered at low temperature. The process involves evaporating and superheating liquid ammonia upstream of the oxidation step, at a pressure which is a multiple of the pressure required for the combustion, using the process heat of the NO.sub.x gases formed during the the combustion and then expanding the superheated ammonia in a turbine, thus generating mechanical energy.

Abstract: The present invention is a process for the control of nitric acid plant stack opacity in the range from 0 to 10 percent during plant startup and shutdown. The process is a series of sequential steps which encompass maximizing pressure, water and air flow to the absorber and adding ammonia upstream of the catalytic combustor. The process is typically accomplished through an automatic control system.

Abstract: To make and use nitrogeneous fertilizer on a farm, nitrogen oxides are prepared in a continuous process from air or from ammonia in a reactor, with the ammonia either being transported to the farm or local site in a farming area or being prepared on the site in a continuous process from water and air. The nitrogen oxides are mixed with a continuous flow of water to form a solution of nitric acid, which may be applied to the field through the irrigation system as top dressing or mixed within the system with ammonium or other cations to form ammonium nitrate or other desired nitrogen solutions for application to the fields in a continuous process or concentrated without requiring storage of large amounts of gas or creating heat exchange problems in the manufacturing process.

Abstract: The invention relates to the compression of a gaseous stream 1. The stream 1 is cooled by a liquid 15 that evaporates at least partially in the gaseous stream. The injected liquid has a composition different from that of the gas to be compressed, and is a component employed in the process in which compression is required and conducted. Alternatively, the liquid is selected from the starting materials to be employed in the process.

Abstract: A method of using solar energy in a chemical synthesis process comprising steam reforming hydrocarbons or gasifying carbonaceous fuel, converting the product of the steam reforming of hydrocarbons or the gasifying of carbonaceous fuels to an ammonia synthesis gas, converting the ammonia synthesis gas to ammonia, supplying the heat required for the steam reforming of hydrocarbons or the gasifying of carbonaceous fuels by a heat transfer fluid, heating the heat transfer fluid in a solar receiver when solar energy is available, heating the heat transfer fluid by combusting a portion of the ammonia when sufficient solar energy is not available to supply the necessary heat to the heat transfer fluid.

Abstract: In a process for producing chemical substances comprising steps of cooling, condensing and solvent-absorbing the reaction product gas having a high temperature formed in a reactor, an absorption type refrigerator or an absorption type heat pump is driven by using, as the driving source, a heat source having such a temperature as not to be advantageous for the heat exchange in the process, which heat source has been taken out of the steps of cooling the reaction product gas, condensing it or solvent-absorbing it to obtain a refrigerant or a hot water having a temperature higher than the temperature of the heat source, and the refrigerant or the hot water is used as a cooling source or a heating source in the steps comprised in said process for producing chemical substances.

Abstract: The invention relates to the recovery of precious metal lost from precious metal-containing catalysts for example the precious metal-containing catalysts which are used in the production of nitric acid by ammonia oxidation. In more detail, a getter (as herein defined) for recovery of precious metal lost from a precious metal-containing catalyst operating at elevated temperature comprises an agglomeration or assemblage of unwoven fibres made from a metal selected from the group ruthenium, palladium, iridium, platinum, gold, silver, rhodium and alloys containing one or more of the said metals. Preferably, the unwoven fibres are randomly oriented.

Abstract: The oxynitride film according to the present invention contains Ga and/or Al and has O/N ratio of at least 0.15. This film is obtained by relying on, for example, chemical vapor deposition technique. The O/N ratio in the film may be varied by, for example, varying the distance between the substrate and the substance-supply source, or by varying the proportion of an oxidizing gas contained in a carrier gas. This film is used either as a surface passivation film of III-V compound semiconductors such as GaAs, or as an insulating film for active surface portions of IG-FET, or as an optical anti-reflective film.This is a division of application Ser. No. 215,442 filed Dec. 11, 1980, now Pat. 4,331,737, which in turn is a continuation of application Ser.No. 23,766, filed Mar. 26, 1979.

Abstract: A device for treating a fluid, in particular a supported catalyst for motor vehicle exhaust gas purification. The device comprises one or more short helically wound lengths of wire at least a surface of which comprises a solid surface coating for interaction with the fluid. For catalysis the coating is a catalytically active material.

Abstract: A process for preparing an improved cobalt oxide catalyst for ammonia oxidation comprising decomposing a cobalt compound such as basic cobalt carbonate by heating to form cobalt oxide, then saturating the cobalt oxide with cobalt nitrate solution and reheating to give an active, durable cobalt oxide catalyst. In ammonia oxidation processes, the durable catalyst of this invention has a long catalyst life and gives improved conversion of ammonia to nitric oxide. Additionally, the catalyst of this invention is capable of performing at higher operating rates than known catalysts. Optimum yields are obtained when the catalyst is prepared from compounds derived from electrolytic grade cobalt.

Abstract: The process and apparatus described seeks to prevent NO.sub.x emissions after an emergency shutdown in a process for manufacturing nitric acid by catalytic combustion of ammonia, compression of the nitrous combustion gases and subsequent absorption. Immediately on shutdown the intake nitrous gas supply to the compressor is interrupted, the residual intake side nitrous gases are conveyed to the delivery side, the delivery side gas volume is shut off, the gas on the delivery side is expanded to the intake side and then exhausted into a vacuum system. Subsequently the acid charged with NO.sub.x in the absorption stages is drawn off, degassed acid is circulated through the absorption stages until equilibrium is established, the pressure of the shutoff section is released and cooled acid is admitted to the absorption stages.

Abstract: A process and a plant are disclosed whereby nitric acid is produced by the catalytic combustion of ammonia with air to form nitrous gases which are contacted with water in an absorption zone to form nitric acid. Gas flow into and through the plant is maintained by a compressor system powered by turbines that are propelled by the heat energy released during ammonia combustion. In accordance with the present invention, a portion of the ammonia combustion heat energy is stored using heat accumulating means positioned at various possible locations throughout the system. Such stored heat provides a thermal energy reserve available to power the compressor turbines for a short period of time in the event that ammonia combustion is discontinued.

Abstract: In a process and apparatus for maintaining the efficiency of ammonia oxidation in a nitric acid plant, the ammonia content of the reactant mixture and the nitrogen oxide content of the reaction product are determined by spectrometry, any nitric oxide in the sample of reaction product first being converted to nitrogen dioxide at elevated temperature and pressure. The apparatus comprises delay means for ensuring conversion of the sample of reaction product before analysis. Analysis may be by UV or IR spectrophotometry or by mass spectrography.

Abstract: An improved process for the manufacture of nitric acid involving catalytic oxidation of ammonia and passage of the resulting nitric oxide through columnar absorption zones, the improvement particularly comprising oxygen-enrichment of that gas passing through the absorption zones at one or more regions of the zones wherein the absorption reaction is from 50 to 90% complete. Further, the invention contemplates the oxygen-enrichment of bleaching air and a reduction in the rate at which bleaching air or other air is taken to form secondary air. The invention results in improved production rates of nitric acid and reductions in the concentration of nitrogen oxides in vent gas.

Abstract: Exhaust gases containing residual nitric oxide constituents from a processing operation are maintained at an elevated pressure, heated to from 260.degree. C. to 340.degree. C. in a separate heat exchanger, and subjected to multi-stage catalytic reduction with ammonia to produce purified exhaust gases. The pressure of the thus purified exhaust gases is then relieved in an expansion turbine.

Abstract: A process for the preparation of nitric acid from nitrogen oxides, oxygen and water which utilizes an aqueous stripping liquid having a nitric acid content within a specified range which passes through a reaction zone. By controlling the process parameters within specified ranges three regions are provided with the reaction zone.

Abstract: Nitric acid having a concentration of at least 98% by weight is obtained from a gaseous stream resulting from catalytic oxidation of ammonia and containing nitrogen oxide and steam, by flowing said stream in an oxidation and condensation column in countercurrent with a stream of nitric acid at 40-60 wt.%, recovering nitrogen peroxide at the top of the column, liquefying said peroxide, bringing it into contact with aqueous nitric acid, oxygen and air in a chemical absorption stage, and distilling the resulting superazeotropic nitric acid. A part of the nitric acid discharged from the oxidation column is directly recycled and the remainder is recycled after distillation to give azeotropic acid and remove water, a part of the latter being used for the chemical absorption.

Abstract: Nitric acid having a concentration of at least 98 wt.% is prepared by recovering in liquid state nitrogen peroxide from a gaseous flow containing the same, by absorption in nitric acid, heating of the resulting solution and liquefaction of the gaseous peroxide evolved, followed by a first chemical absorption of a fraction of the liquid peroxide with nitric acid at 70-80% and air and distillation of the resulting concentrated nitric acid. The gaseous products discharged from said first absorption and comprising unreacted peroxide and air are contacted with nitric acid and water in a second chemical absorption stage, thereby to produce the nitric acid used in the first absorption. The remaining fraction of liquid peroxide is delivered to the distillation column, discharged at the top thereof and recycled to the liquefaction stage, while nitric acid is extracted at the bottom of the distillation column and recycled to the second absorption stage.

Abstract: Nitric acid having a concentration of at least 98 wt.% is produced from nitrogen peroxide by absorbing the latter in superazeotropic nitric acid, distilling the resulting solution so as to recover nitric acid at a concentration of at least 98 wt.% and nitrogen peroxide, liquefying the latter and reacting it in a first stage with aqueous nitric acid (70-80% wt.%) and air and delivering the resulting superazeotropic nitric acid, together with the solution, to the distillation column. Nitrogen peroxide and oxygen unreacted in the first stage are contacted with nitric acid at 68-75 wt.% in a second stage, thus to produce said aqueous nitric acid fed to the second stage. The said nitric acid at 68-75 wt.% and the superazeotropic acid used for the absorption are extracted from the bottom part of the distillation column.

Abstract: In the operation of a nitric acid plant, the rate of flow of process air to the converter in which ammonia is oxidized is controlled by injection of steam at regulated rates into the heated tail gas from the nitric acid production, thereby utilizing regulated mass flow power augmentation in the gas used for powering the expansion turbines employed in driving the compressors operated to furnish required process air at superatmospheric pressure to the nitric acid plant.

Abstract: The invention concerns catalytic substances for the oxidation of ammonia, for the production of nitric acid, comprising cobalt oxide as the main component. Such substances, besides cobalt oxide, also contain additives formed of aluminum oxide and possibly oxides of thorium, cerium, zinc and cadmium, the amount of aluminum oxide added being from 5% to 15% by weight of the finished substances and the amount of the other oxides being from 0 to 25% by weight of the finished substances; these substances are in particular shaped by pelleting or extrusion, dried and then calcined at temperatures of the order of from 900.degree. to 1000.degree.C. The advantages of these catalytic substances lie in a high degree of activity and a high level of strength, which are maintained during use thereof.