Ammonia, decomposition oxidation

In a later study by the Schmidt group (27), electron microscopy was used to characterize morphological changes in microspheres (<0.6 cm in diameter) of Pt, Rh, Pd, and Pt-Rh alloy in a number of reaction environments the reactions were ammonia oxidation, ammonia decomposition, and propane oxidation. No other experimental techniques, such as weight-loss measurements, were employed. After prolonged exposure to reaction mixtures of ammonia and air at temperatures less than 727°C, the surfaces of the spheres were reconstructed to favor specific crystal planes. The structure of the facets was found to be a function of the reaction mixture, temperature, and metal (Fig. 13). In the same reaction mixtures, as well as in pure ammonia at higher temperatures... 

According to A. Hantzsch and L. Kaufmann,1 if dry ammonia be passed into the ethereal soln. of hyponitrous acid, ammonium hydrohyponitrite, (NH4)HN202, or NH4O.N N.OH, is formed in colourless crystals which melt with turbulent decomposition at 64°-65°. The salt spontaneously decomposes into ammonia, nitrous oxide, and water. The salt dissolves in water with an alkaline reaction. Ammonium hyponitrite, NH4O.N H.ONH4, cannot be prepared directly, but... 

The above procedures for catalyst preparation have generally provided excellent results. Especially important are surface-sensitive reactions. With supported catalysts in which the active components have a narrow particle-size distnbution, the optimum particle size for a demanding reaction can be established. Major improvements of supported catalysts, e.g. with respect to carbon deposition and ammonia decomposition, can be achieved by preparing catalysts with a narrow par-ticle-size distribution. Also, the preparation of catalysts in which the active components have a uniform chemical composition is highly important One instance is the preparation of supported vanadium oxide phosphorus oxide (VPO) catalysts for the selective oxidation of w-butane to maleic anhydride, which has been carried out using vanadium(III) deposition onto silica [31]... 

Thus, ammonia does not reduce magnetite at an appreciable rate at temperatures below 450°C., and it appeal s that at 450°C. and above, the reduction may be accomplished by decomposition products of ammonia rather than by ammonia itself. This contention is based on the fact that the reduction of fused catalysts with ammonia at 450°C. and 550°C. appeared to be an autocatalytic process that is, the rate of reduction increased with time in the initial part of the experiment. Reduction with hydrogen does not appear to be autocatalytic. It may be postulated that a-iron and nitride formed in the reduction are better catalysts for the ammonia decomposition than iron oxide. 

Dealuminated M-Y zeolites (Si/Al = 4.22 M NH4, Li, Na, K, Cs) were prepared using the dealumination method developed by Skeels and Breck and the conventional ion exchange technique. These materials were characterised by infrared spectroscopy (IR) with and without pyridine adsorption, temperature-programmed desorption (t.p.d.) of ammonia. X-ray difiracto-metry (XRD) and differential thermoanalysis (DTA). They were used for encapsulation of Mo(CO)5. Subsequent decarbonylation and ammonia decomposition was monitored by mass spectrometry (MS) as a function of temperature. The oxidation numbers of entrapped molybdenum as well as the ability for ammonia decomposition were correlated to the overall acidity of the materials. It was found that the oxidation number decreased with the overall acidity (density and/or strength of Bronsted and Lewis acidity). Reduced acidity facilitated ammonia decomposition. 

The dual-state behaviour of RU-AI2O3 catalysts may also arise from metal-support interaction. In the oxidized state, the catalyst was more selective for nitrogen formation in NO reduction than when in the reduced state. It was also active for the water-gas shift reaction whereas the reduced form was rather inactive and differences were also observed for ammonia decomposition and the CO-H2 reaction. The more active form does not appear to contain ruthenium oxide the reduced catalyst may have been de-activated by reaction with the support and its transformation to the more active form by oxidation may involve surface reconstruction and/or destruction of the metal-support interaction. 

The process is usually operated with excess of methane to maximize yield of HCN on ammonia used. Oxygen and methane react completely and some ammonia is recovered, but the presence of nitrogen in the products indicates that some ammonia decomposition occurs. Again the proportion of hydrogen in the product indicates some cracking of the methane as well. Traces of acetonitrile and acrylonitrile may also be found but oxides of nitrogen are not found under these conditions. 

AMMONIUM OXALATE, ANHYDROUS (1113-38-8) CjHsNj04 (Fire Rating 1). Incompatible with acids, ammonium acetate furfliryl alcohol, silver, sodium chlorite, sodium hypochlorite oxidizers. Attacks many metals. Heat of decomposition or fire produces fumes of ammonia, nitrogen oxides, carbon monoxide, carbon dioxide, formic acid. Attacks steel. On small fires, use foam, dry powder, water, or CO2 extinguishers. 

COBALT MURIATE (7646-79-9 7791-13-1, hexahydrate) C0CI2 Noncombustible solid. Incompatible with bases, alkali metals, ammonia vapors oxidizers, acetylene reaction may be violent. Contact with acids or acid fumes can produce highly toxic chloride fumes. Aqueous solution is a weak acid. Incompatible with metals can cause pitting attack and stress corrosion in austenitic stainless steels. Thermal decomposition releases toxic HCl, cobalt fumes, cobalt oxides. Cobalt is a known animal carcinogen. 

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