Combination step ammonia oxidation

Ammonia oxidation was included in the detailed model [12] (results not included). In this model, two reaction steps were added, where ammonia on the surface was oxidized either with oxygen alone or in a second step in a combination with hydroxyl groups. The hydroxyls are produced according to ... 

All nitric acid plants are based on the same basic chemical operations 1) Oxidation of ammonia with air to give nitric oxide, 2) Oxidation of the nitric oxide to nitrogen dioxide and 3) Absorption in water to give a solution of nitric acid. The efficiency of the first step is favored by low pressure whereas that of the second step is favored by high pressure. These considerations, combined with economic reasons give rise to two types of nitric acid plants - single pressure and dual pressure97. 

In the converter, the ammonia reaas completely, with 97% forming NO and the balance forming N2. In the short time in which the reaction mixture is in the presence of the catalyst (less than 0.001 s), a negligible amount of NO2 is formed. The product gas is subjected to a series of cooling and hydration steps in which the NO is completely oxidized to NO2, which in turn combines with water (some of which is present in the product gas, the rest of which is added) to form a 55 wt% aqueous nitric acid solution. The NO formed in the latter reaction is reoxidized and the added NO2 is hydrated to form still more HNO3. The product gas from the process may be taken to contain only N2 and O2. A simplified flowchart of the process follows. 

The off gases from the Thorex waste pass through a caustic scrubber to remove the oxides of nitrogen prior to being combined with the Purex waste off-gases. This step is necessary since ammonia is evolved from the Purex waste and the combination of gaseous ammonia with oxides of nitrogen forms ammonium nitrate which sublimes on the filter media... 

Another mechanism for induced codeposition of Mo was suggested by Chassaing et al for electrodeposition of Mo-Ni alloys from citrate-ammonia electrolytes. Electrochemical impedance spectroscopy (EIS) measurements were carried out in order to better understand the different reactions occurring on the electrode surface during deposition. The proposed mechanism is based on a multi-step reduction of molybdate species. A M0O2 layer is formed via reduction of molybdate ion as in Eq. (42). Then, if free Ni is present in solution, this oxide can first combine at low polarization with Ni, following the reduction reaction ... 

Triethanolamine is produced from ethylene oxide and ammonia at 5 atm total pressure via three consecutive elementary chemical reactions in a gas-phase plug-flow tubular reactor (PFR) that is not insulated from the surroundings. Ethylene oxide must react with the products from the first and second reactions before triethanolamine is formed in the third elementary step. The reaction scheme is described below via equations (1-1) to (1-3). All reactions are elementary, irreversible, and occur in the gas phase. In the first reaction, ethylene oxide, which is a cyclic ether, and ammonia combine to form monoethanolamine ... 

This reaction was first reported by MacDonald and Fischer in 1952. It is the degradation of hexoses into pentoses involving the steps of formation of dithioacetal, oxidation to unsaturated disulfone by means of perphthalic acid, hydrazine treatment, and benzalde-hyde splitting of the corresponding hydrazone. Therefore, the whole process is known as the MacDonald-Fischer degradation. In addition, when the unsaturated disulfone is dissolved in aqueous ammonia or methanol saturated with ammonia, 2-deoxy-2-amino sugar is resolved. This reaction in combination with mass spectroscopy was used to study the structure and stereochemistry of carbohydrates. ... 

The preparation of alkyl derivatives of ammonia suggested a further step. Hofmann and Cahours (in London) investigated the corresponding derivatives of phosphine, PH3, some of which had been prepared by P. Thenard. They obtained triethylphosphine, P(C4H5)3, by the very violent reaction between zinc ethyl and phosphorus trichloride in ether, and showed that it forms an oxide and sulphide by direct combination, combines with hydrogen chloride, bromide, and iodide, and with ethyl iodide to form P(C4H5)4l. Hofmann found that triethylphosphine forms a red crystalline compound, P(CaH5)3, CS2, with carbon disulphide, which can be used as a test for this in coal gas. 

The first step consists of the air oxidation of cyclohexane to a mixture of cyclohexanol and cyclohexanone as described in Section 9.2.2.1. The mixture is fractionated by distillation and the cyclohexanol is dehydrogenated to cyclohexanone over a catalyst such as copper. The combined cyclohexanone fractions are then treated with aqueous hydroxylamine sulphate at 20—95°C to form the oxime. The reaction mixture is neutralized with aqueous ammonia or sodium hydroxide and the crude oxime separated as an oily layer. This is stirred with concentrated sulphuric acid at 120 C and the oxime undergoes the Beckmann rearrangement to give caprolactam. In one process, the solution containing the lactam is continuously withdrawn from the reactor and rapidly cooled to below 75°C to minimize hydrolysis. The solution is then further cooled and neutralized with aqueous ammonia. Crude caprolactam separates as an oil and is purified by distillation under reduced pressure. 

In the combined process, artunonium sulfate formed by oxidation of sulfite is concentrated to a slurry, then decomposed at 600° to 700°F in a step similar to that used in die ABS process. The liberated SOj is reduced in an H2S generating unit which can utilize reducing gas from a coal gasifier. The gmietation of H2S is controlled to luoduce a two-to-one ratio of H2S to SO2 for feed to the IFP liquid Qaus reactin. Ihe products of tins unit are molten sulfur and anunonia. The ammonia is condensed from die Claus plant tail gas, concautated, and recycled to the absorb - (Radian, 1977). 

Pyridines can be made by condensation reactions of acyclic starting materials such as carbonyl compounds with ammonia. The most general of these methods is the Hantzsch pyridine synthesis. In this reaction, two molecules of a j8-dicarbonyl compound, an aldehyde, and ammonia combine in several steps (Worked Example 25-28) to give a substituted dihydropyridine, which is readily oxidized by nitric acid to the aromatic system. When the j8-dicarbonyl compound is a 3-ketoester, the resulting product is a 3,5-... 

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