Abstract: Wires of platinum containing 4 to 12% rhodium or 4 to 12% of palladium and rhodium (4 to 12% being in reference to the sum of palladium and rhodium and not the percent values for each individually) and wires of palladium containing 2 to 15% nickel or 2 to 15% copper or 2 to 15% of nickel and copper (2 to 15% being in reference to the sum of nickel and copper) and having a diameter of 50 to 120 .mu.m, a tensile strength of 900 to 1050 N/mm.sup.2 and an elastic limit of 0.5 to 3% are used for the knitting of round nets for use as catalysts in the oxidation of ammonia and as recovery nets for platinum metals. A flat knitting machine with a gauge of 3.63 to 1.81 mm is also used whereby the loop length is 2 to 6 mm and wherein the loop or width gauge corresponds with the knitting machine gauge so as to provide a loop width of 1.81 to 3.63 mm.

Abstract: A fabric knitted from a precious metal fibre, especially platinum or palladium or alloys thereof, offers advantages as a catalyst gauze, for example in ammonia oxidation. A method for knitting at high weights involves the co-feeding of a supplementary fibre with the metal fibre.

Abstract: The present invention relates to processes and apparatus for mixing oxidizable reactants with oxidant and oxidizing oxidizable reactants. When ammonia is used as the reactant, nitric acid can be obtained. Through using particular mixing and oxidizing arrangements, the volume of reactant oxidized can be significantly increased.

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: 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: A fabric knitted from a precious metal fibre, especially platinum or palladium or alloys thereof, offers advantages as a catalyst gauze, for example in ammonia oxidation. A method for knitting at high weights involves the co-feeding of a supplementary fibre with the metal fibre.

Abstract: This invention is a catalytic element for use in the catalytic oxidation of ammonia. The element comprises a foraminous structure fabricated from a material consisting essentially of a metal selected from the group consisting of platinum, rhodium, palladium and alloys of mixtures thereof characterized by (a) a novel configuration whereby the initial product of the formula: curve the flat ratio (C/F) multiplied by mesh count in inches (N) and wire diameter (d.sub.w), for said element is greater than at least about 0.08 and (b) where, for a given hydrogen throughput, the conversion efficiency is a function of the curve to flat ratio (C/F), wire diameter (d.sub.w) and mesh count (N) combination and conversion efficiency is improved by increasing the mesh count (N) for a given wire diameter, increasing the wire diameter (d.sub.w) for a given mesh count, and increasing the curve to flat ratio (C/F) to a ratio of above 1.0. Preferably the initial product of the formula is greater than 0.2, more preferably 0.

Abstract: Method of low temperature start-up of ammonia oxidation plants by passing hydrogen and oxygen over platinum containing gauzes bearing a platinum coating having a surface area in excess of about 50 cm.sup.2 /g, thereby heating them to temperatures which are sufficient for catalytic oxidation of ammonia.

Abstract: A process for the recovery of sulphuric acid from a waste acid stream containing ammonium sulphate comprising vaporizing the waste acid and subsequently converting the ammonia and sulphur dioxide generated to nitrogen and sulphur trioxide, respectively. The process provides an economic method for the regeneration of the waste sulphuric acid from a methyl methacrylate production process.

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: A catalyst pack (1) for the manufacture of nitric acid by oxidizing ammonia comprises at least one layer (2, 3, 4, 5, 6) of elongate elements made from at least one platinum group metal or alloy and at least one foraminous layer (7, 8) of ceramics material having a coating of one or more platinum group metals or alloys or mixture. In use the catalyst pack has improved conversion efficiencies. The preferred ceramics material comprises either alumina, slicia and boria or zirconia in the form of a cloth.

Abstract: Platinum-rhodium and platinum-palladium-rhodium gauzes bearing a high surface area coating (in excess of 50 cm.sup.2 /g) of platinum ease initiation of ammonia oxidation.

Abstract: A process for the catalytic gaseous phase reaction of a reactive gas wherein the heat of reaction generated produces a temperature elevation of less than about 150.degree. C. in the substantially adiabatic reaction system, the improvement comprising:heating the cold reactive gas by passing it through a heated regenerative material present in the first portion of a vessel;passing the heated reactive gas through a solid catalyst for the reaction present in a second portion of the vessel to form a gaseous product stream;redirecting the gaseous product stream;passing the redirected gaseous product stream through the solid catalyst for the reaction present in the second portion of the vessel to form additional gaseous product,cooling the gaseous product stream by passing it through a cooled regenerative material present in the first portion of the vessel; andperiodically reversing the flow direction in the portions of the reaction system.

Abstract: A process for the manufacture of nitric oxide by the oxidation of ammonia using a catalyst (1) comprising platinum in which the ammonia conversion efficiency of the process is improved by the use of a palladium catchment trap (2) in which the conventional layers (8 and 10) of palladium scavenger-wire are adjacent to layers (7, 9 and 11) of interstitial (preferably woven) ceramics material. The preferred ceramics material consists of alumina, silica and boria. Also a catchment trap comprising layers of ceramics material for use in the 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: To make non-pressure nitrogenous fertilizer solutions, nitrogen oxides are prepared in a continuous process by burning ammonia in contact with a cobalt oxide catalyst started by an electric arc without preheating the gases. This burning forms nitrogen oxides which are reacted under negative pressure in a two-stage system. Nitric acid is formed in the first stage from a portion of the oxides by oxidzing them to nitrogen dioxide and reacting the nitrogen dioxide with water. In the second stage, the remaining nitrogen oxides are reacted at a pH between 8.0 and 8.4 in a gas-liquid contacting apparatus with an ammonium hydroxide reaction liquid, formed by mixing ammonia and water. The ammonium nitrite solution formed in the second stage is mixed with the nitric acid at a pH below 0.2, resulting in a solution of acidic ammonium nitrate to be flowed to the fields with irrigation water.

Abstract: Nitric oxide is formed by the oxidation of ammonia. An ammonia containing gas is contacted with an oxidation catalyst comprising stainless steel in the presence of oxygen at a temperature between about 500.degree. C. and 1100.degree. C. in order to effect a reaction selectivity of at least 50%.

Abstract: To make non-pressure nitrogenous fertilizer solutions, nitrogen oxides are prepared in a continuous process by burning ammonia in contact with a cobalt oxide catalyst started by an electric arc without pre-heating the gases. This burning forms nitrogen oxides which are reacted under negative pressure in a two-stage system. Nitric acid is formed in the first stage from a portion of the oxides by oxidizing them to nitrogen dioxide and reacting the nitrogen dioxide with water. In the second stage, the remaining nitrogen oxides are reacted at a pH between 8.0 and 8.4 in a gas-liquid contacting apparatus with an ammonium hydroxide reaction liquid, formed by mixing ammonia and water. The ammonium nitrite solution formed in the second stage is mixed with the nitric acid at a pH below 0.2, resulting in a solution of acidic ammonium nitrate to be flowed to the fields with irrigation water.

Abstract: To make and use nitrogenous fertilizer on a farm, nitrogen dioxide is prepared in a continuous process from air or from ammonia in a reactor, with the ammonia either being transported to the farm or being prepared on the farm in a continuous process from water and air. The nitrogen dioxide is mixed with a continuous flow of water to form a dilute solution of nitric acid, which may be applied to the field through the irrigation system as top dressing or mixed within the irrigation system with ammonia 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. In the embodiment which burns ammonia, the nitrogen oxides are fixed on an 8 percent nickel stainless steel mesh in a column 10 feet high and one foot in diameter and oxidized while fixed to nitrogen dioxide.

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: Improved recovery of platinum lost from the catalyst gauze in a nitric acid plant is obtained by using palladium containing recovery gauzes configured to enhance the mass transfer characteristics of the system.

Abstract: Selective reduction of NO.sub.x with NH.sub.3 as well as decomposition of excess NH.sub.3 is provided over a wide temperature range by a platinum-gold catalyst.

Abstract: This invention is concerned with the application of fibrous products from platinum group metal or platinum group metal alloys to the oxidation of ammonia in the manufacture, for example, of nitric acid and to the production of hydrogen cyanide in the Andrassow Process. In particular, the invention relates to a catalyst assembly including an agglomeration or assemblage of randomly oriented fibres made from a platinum group metal or an alloy containing at least one platinum group metal, gold or silver. The fibres used in the catalyst assembly are preferably produced by melt extraction or melt spinning processes.

Abstract: Improved recovery of platinum lost from the catalyst gauze in a nitric acid plant is obtained by using palladium containing recovery gauzes configured to enhance the mass transfer characteristics of the system.

Abstract: This invention relates to a laminated article, particularly to such an article comprising a gauze pack containing two or more gauzes such as are typically used as catalyst catchment or getter means in nitric acid production plants.Specifically, this invention provides a gauze pack segment suitable for locating in planar contiguous relationship with one or more further gauze pack segments to provide a gauze pack having a predetermined, for example, a regular geometric shape comprises a plurality of superposed gauze segments having at least when assembled substantially identical shape and area and held in fixed relationship one with another.

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: Nitric oxide is formed by the oxidation of ammonia. An ammonia containing gas is contacted with an oxidation catalyst deposited on a surface of a solid electrolyte while an oxygen containing gas is contacted with a second catalyst capable of dissociating oxygen gas to oxygen ion deposited upon a second surface of the solid electrolyte. Oxygen ion is transported through the solid electrolyte to react with ammonia to form nitric oxide under simultaneous production of electric energy.

Abstract: Noxious nitrogen oxides in a waste gas stream such as the stack gas from a fossil-fuel-fired power generation plant or other industrial plant off-gas stream is catalytically reduced to elemental nitrogen and/or innocuous nitrogen oxides employing ammonia as reductant in the presence of a zeolite catalyst in the hydrogen or sodium form having pore openings of about 3 to 10 A.

Abstract: This invention relates to catalysts suitable for the catalytic oxidation of hydrocarbons and carbon monoxide and for the catalytic reduction of oxides of nitrogen in the presence, respectively, of suitable oxidizing and reducing means. The invention is especially concerned with catalysts which are suitable for the catalytic purification or control of the exhaust gases of petrol driven internal combustion engines and of diesel engines. Such catalysts have been variously described as "three-way", "polyfunctional" and "multi-functional" catalysts. In more detail a three way catalyst of the invention comprises a substrate having supported thereon at least one intermetallic compound of the general formula A.sub.x B.sub.y where A represents one or more Groups VIII metals having an atomic number not larger than 78; B represents one or more metals of the group consisting of Al, Sc, Y, the lanthanides, Ti, Zr, Hf, V, Nb and Ta and x and y are integers.

Abstract: A catalyst comprising a substrate having deposited thereon a first coating containing a refractory metal oxide and having deposited upon the said oxide one or more intermetallic compounds of the general formula A.sub.x B.sub.y where A is selected from the group consisting of Ru, Rh, Pd, Ir and Pt, and B is selected from the group consisting of Al, Sc, Y, the lanthanides, Ti, Zr, Hf, V, Nb, and Ta, and where x and y are integral and may have values of 1 or more.

Abstract: 1,3-Diaryl triazenes, e.g., 1,3-diphenyltriazene, intermediates in the synthesis of aromatic diamines, e.g., p-phenylenediamine, are prepared by catalytically oxidizing ammonia, and subsequently the resulting nitric oxide, with a gas comprising diluted molecular oxygen, e.g., air, so as to produce a gas mixture containing dilute NO.sub.x, i.e., NO.sub.2 preferably admixed with NO, x being (1 + n), wherein n is the NO.sub.2 fraction of the NO.sub.x ; and contacting the gas mixture, preferably at a temperature in the range of about from 25.degree. to 350.degree. C., with excess primary aromatic monoamine, e.g., aniline, so as to result in a monoamine temperature in the range of about from 25.degree. to 90.degree. C., preferably 40.degree. to 60.degree. C., during contact. Highest yields of triazene are obtained when the x in NO.sub.x is about from 1.3 to 1.7, and the amount of NO.sub.

Abstract: This invention relates to the catalytic oxidation of ammonia. The catalytic compounds are complex catalysts with limited porosities, with specific surface areas between 0.02 and 2 m2/g, containing an active material bonded by ceramic-type bonds to the elements of a refractory carrier made of refractory oxides such as magnesia, zirconia, silica.Such compounds are suitable for the oxidation of ammonia over fixed beds or fluidized beds.

Abstract: There is provided a catalyst for the oxidation of ammonia for the production of nitrogen oxides consisting of a gauze packet of platinum-rhodium alloy and non-noble metal alloys in which at least a part of the individual gauzes of the gauze packets contain both wires of platinum-rhodium alloy and also of oxidation resistant, heat resistant non-noble metal alloys.

Abstract: This invention relates to a laminated article, particularly to such an article comprising a gauze pack containing two or more gauzes such as are typically used as catalyst catchment or getter means in nitric acid production plants.Specifically, this invention provides a gauze pack segment suitable for locating in planar contiguous relationship with one or more further gauze pack segments to provide a gauze pack having a predetermined, for example, a regular geometric shape comprises a plurality of superposed gauze segments having at least when assembled substantially identical shape and area and held in fixed relationship one with another.