Ammonium nitrate , thermal decomposition

However, Feick and Hainer [18] consider most of the above figures of the energy of activation are not very accurate as in the period prior to explosion a considerable quantity of ammonium nitrate is evaporated. The authors suggest the following equations for ammonium nitrate thermal decomposition ... 

EXPLOSION and FIRE CONCERNS combustible solid flammable moderate fire risk NFPArating (not rated) volatile in steam contact with strong oxidizing agents may cause fires and explosions violent reaction with ammonium perchlorate incompatible with tetrani-tromethane and mercury (II) nitrate thermal decomposition may generate carbon monoxide and carbon dioxide use alcohol foam, water spray, dry chemical powder, or carbon dioxide for fire fighting purposes. 

Chromia—alumina catalysts are prepared by impregnating T-alumina shapes with a solution of chromic acid, ammonium dichromate, or chromic nitrate, followed by gentie calciaation. Ziac and copper chromites are prepared by coprecipitation and ignition, or by thermal decomposition of ziac or copper chromates, or organic amine complexes thereof. Many catalysts have spiael-like stmctures (239—242). 

Dinitrogen oxide, N20, gas was generated from the thermal decomposition of ammonium nitrate and collected over water. The wet gas occupied 126 mL at 21°C when the atmospheric pressure was 755 Torr. What volume would the same amount of dry dinitrogen oxide have occupied if collected at 755 Torr and 21°C The vapor pressure of water is... 

According to an O.S. amendment sheet, the procedure as described [1] is dangerous because the reaction mixture (dicyanodiamide and ammonium nitrate) is similar in composition to commercial blasting explosives. This probably also applies to similar earlier preparations [2]. An earlier procedure which involved heating ammonium thiocyanate, lead nitrate and ammonia demolished a 50 bar autoclave [3], TGA and DTA studies show that air is not involved in the thermal decomposition [4], Explosive properties of the nitrate are detailed [5], An improved process involves catalytic conversion at 90-200°C of a molten mixture of urea and ammonium nitrate to give 92% conversion (on urea) of guanidinium nitrate, recovered by crystallisation. Hazards of alternative processes are listed [6],... 

Catalytic elfects on the thermal decomposition and burning under nitrogen of the nitrate were determined for ammonium dichromate, potassium dichromate, potassium chromate, barium chloride, sodium chloride and potassium nitrate. Chromium(VI) salts are most effective in decomposition, and the halides salts during burning of the nitrate [1]. The effect of chromium compounds soluble in the molten nitrate, all of which promote decomposition of the latter, was studied (especially using ammonium dichromate) in kinetic experiments [2],... 

Self-sustaining thermal decomposition of NPK fertilisers is apparently possible if crystalline potassium nitrate is present from a exchange reaction of ammonium nitrate [1], Almost pure fertiliser grades of ammonium nitrate are legally restricted in some countries because of its instability [2],... 

Catalysts suitable specifically for reduction of carbon-oxygen bonds are based on oxides of copper, zinc and chromium Adkins catalysts). The so-called copper chromite (which is not necessarily a stoichiometric compound) is prepared by thermal decomposition of ammonium chromate and copper nitrate [50]. Its activity and stability is improved if barium nitrate is added before the thermal decomposition [57]. Similarly prepared zinc chromite is suitable for reductions of unsaturated acids and esters to unsaturated alcohols [52]. These catalysts are used specifically for reduction of carbonyl- and carboxyl-containing compounds to alcohols. Aldehydes and ketones are reduced at 150-200° and 100-150 atm, whereas esters and acids require temperatures up to 300° and pressures up to 350 atm. Because such conditions require special equipment and because all reductions achievable with copper chromite catalysts can be accomplished by hydrides and complex hydrides the use of Adkins catalyst in the laboratory is very limited. 

Nitrous Oxide Nitrous oxide (1.1.11) is synthesized either by the thermal decomposition of ammonium nitrate, or by the oxidation of sulfamic acid by nitric acid [9-11]. 

Thermal decomposition of symmetrical hydrazines (212a-d) according to equation 30 resulted in excellent yields of hindered esters (231a-d). The hydrazines leading to the esters were generated as intermediates by the oxidation of Af-alkoxyamides using ceric ammonium nitrate or Ni02.H20 (Scheme 31). 

Nitric oxide is commercially produced by the catalytic oxidation of ammonia using a platinum catalyst 4NH3(g) + 50 —> 4NO(g) + 6H20(g). Nitrous oxide is produced by the thermal decomposition of ammonium nitrate at approximately 240°C NH4N03(g) —> N O + 2H . ... 

It is worth emphasizing that the reaction scheme above is able to explain not only the stoichiometry of the fast SCR reaction, and specifically the optimal equimolar NO to N02 feed ratio, but also the selectivity to all of the observed products, namely N2, NH4NO3 and N20, which derives from thermal decomposition of ammonium nitrate (Ciardelli et al., 2004b, 2007a Nova et al., 2006b) furthermore it is in agreement with the observed kinetics of the fast SCR reactions, which at low temperature is limited by the rate of the reaction between nitrate and NO. 

Thermal decomposition. According to A. J. B. Robertson [12] a very high activation energy, E = 40.5 kcal/mole, characterizes the thermal decomposition of ammonium nitrate. 

Fig. 170. Thermal decomposition of ammonium nitrate (pure and with varying quantities of ammonium chloride) at 200°C (broken line) and 250°C. —induction period in min, according to Guiochon and Jacque.

Thermal decomposition of ammonium nitrate can also be facilitated by adding organic compounds. Thus, ammonium nitrate mixed with cellulose begins to decompose at 100°C and decomposition becomes distinctly perceptible at 120°C. Also salts of some organic bases (e.g. pyridine nitrate) considerably lower the temperature of decomposition of ammonium nitrate. 

Pure ammonium nitrate when hermetically confined can be made to explode by rapid heating to a temperature above 200°C. Thus, for example Herguet [34] reports that ammonium nitrate confined hermetically undergoes an explosive decomposition on being heated to a temperature of 260-280°C. On the other hand attempts to bring about an explosion of ammonium nitrate that was not perfectly confined failed. Sherrick [35] has established that ammonium nitrate non-hermetically confined does not decompose explosively due to a thermal reaction, but will do so if brought in contact with molten iron. 

The copper chromium oxide (Cu/Cr = 1) has been prepared by coprecipitation of copper and chromium nitrates with ammonium hydroxide, followed by thermal decomposition in flowing nitrogen up to the final temperature (370"C), according to a previously described method (8). The apparatus and the catalytic procedure have also been described elsewhere in case of gas phase reactions (5) and liquid phase reactions (7). 

The classic way of N20 preparation is the thermal decomposition of ammonium nitrate ... 

Dissolving is often an endothermic process. For example, when ammonium nitrate dissolves in water the temperature of the water falls, indicating that energy is being taken from the surroundings. Photosynthesis and thermal decomposition are other examples of endothermic processes. 

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