Nitric acid, catalytic decomposition

A runaway decomposition in a melting vessel associated with distillation of the crude product burst the vessel and led to a major fire. The short report does not include detailed circumstances. The decomposition was attributed to the catalytic effects of impurities. However, it seems that nitric acid was also present. 

Our approach utilized the metals gold, platinum, then later gold, platinum, and nickel electroplated in succession because the catalytic decomposition of hydrogen peroxide reaction we tested was most efficiently catalyzed with platinum.After fabrication of the nanowires they were freed by removing the conductive silver backing with nitric acid and the sacrificial template with a strong base, sodium hydroxide. Then nanorods were washed with deionized water and ultracentrifuged to achieve a neutral pH. 

Some of the important reactions in contemporary technology involve NO, which is a designation of N2O, NO, and NO2, and was one of the first examples in this book. The formation of these molecules in combustion processes is a major source of air pollution, and the catalytic oxidation of NH3 to NO on R surfaces is used to produce nitric acid, a major industrial chemical. The decomposition of NO, to N2 is a major process in the automotive catalytic converter. 

Rice and Getz J made a very complete study of the matter from this point of view. At 65° C. they found k = 0-286, compared with the value 0-292 of Daniels and Johnston. In order to test the possibility that the reaction might depend on catalysis by dust, they compared the velocity constants for filtered and unfiltered nitrogen pentoxide and for gas which had been passed through an electrical dust precipitator. In some experiments the gas was dried with phosphorus pentoxide, in others not. In some it was prepared by the dehydration of nitric acid with phosphorus pentoxide and in others by the action of chlorine on silver nitrate. Nitric acid was found to have no catalytic effect on the decomposition. Some of the principal results are summarized below, all data referring to 65° C. 

E. C. C. Baly and H. M. Duncan studied the decomposition of ammonia by means of a hot platinum wire. Two types of ammonia may be prepared—an inactive and an active modification—which are decomposed to different extents by the same quantity of energy. The active form is obtained by the slow withdrawal of ammonia from a cylinder containing the compressed gas by warming the cone. aq. soln. and drying the gas by quicklime and by isothermal evaporation of the liquefied gas at its b.p. The inactive form is obtained by the rapid evaporation of the liquefied gas. The inactive gas slowly recovers its activity on remaining in contact with the liquefied gas. The same effect can be produced by gently warming the gas by means of a platinum wire heated at 200°. In order to observe these phenomena, the platinum wire must be activated in the same way as is customary in W. Ostwald s process for the catalytic oxidation of ammonia in air to nitric acid. Alternatively,... 

The propulsion assembly of a rocket or -> Missile. The driving force can be produced by burning liquid fuels in liquid oxidizers (liquid oxygen, nitric acid, or other oxidants such as liquid fluorine), by burning of solid propellants (-> Solid Propellant Rockets), by burning solid fuels in liquid oxidizers (-> Hybrids), or by catalytic decomposition of endothermal compounds (-> Hydrazine-, - Aerozim, - Aurol). 

A peroxide, probably Ag203, is stated to be produced by anodic oxidation of silver in acid solution.4 When solutions of sodium or potassium persulphate react with silver or silver nitrate, a peroxide with a higher percentage of oxygen than Ag2Oa is produced, the process being attended by catalytic decomposition of the persulphate with formation of the acid sulphate. Ammonium persulphate does not yield a peroxide, but the ammonium radical becomes oxidized to nitric acid.6... 

Traces of ferric salts retard the dissolution of mercury in nitric acid, a phenomenon which is attributed5 to decomposition of the nitrous acid by the catalytic alternate reduction and oxidation of the iron-radicle. 

The solubility of gases in solids imposes a serious limitation on the thermo-gravimetric method, as discussed by Guiochon (50). It is difficult to eliminate or even measure and is generally unknown. This was shown by the heating of solid ammonium nitrate initially containing I % nitric acid at 200°C for 3 h. At the end of this period, the sample contained 0.6% nitric acid. This acid has no catalytic effect on the decomposition of the sample, which gives no nitric acid under these conditions, so that only the slowness of its evaporation... 

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