Nitrous decomposition process

In a similar way to nitrite, although at a somewhat lower rate, nitrous acid can be oxidised by the hydroxyl radical [35,43], Furthermore, it also undergoes a thermal decomposition process that parallels the photoinduced reaction [53]. 

The process developed by Radici includes a multi-bed reactor (Figure 7.5) [10]. The gaseous flow containing N2O is subdivided into three flows that are fed separately to the three catalytic layers. The flow from the final catalytic bed exhibits a residual nitrous oxide content below 500 ppm and is subdivided into two flows, one being vented to the atmosphere and one being mixed with the feed to the first catalytic bed and re-circulated into the nitrous oxide decomposition process. 

Nitrate esters can be autocatalyzed to accelerate the decomposition [45]. The trace nitroxides, which are formed in the decomposition process of nitrate esters, could combine with trace water to form nitric acids or nitrous acids. Those acids would accelerate the decomposition reaction of nitrate esters. 

PCSs obtained by dehydrochlorination of poly(2-dilorovinyl methyl ketones) catalyze the processes of oxidation and dehydrogenation of alcohols, and the toluene oxidation207. The products of the thermal transformation of PAN are also catalysts for the decomposition of nitrous oxide, for the dehydrogenation of alcohols and cyclohexene274, and for the cis-tnms isomerization of olefins275. Catalytic activity in the decomposition reactions of hydrazine, formic acid, and hydrogen peroxide is also manifested by the products of FVC dehydrochlorination... 

Ionizing radiation decomposes gaseous nitrous oxide131-136 into N2, 02, and nitrogen oxides by a series of secondary reactions following primary formation of N20 and N20+. The secondary processes include reactions of neutral fragments and of ionic species and are of considerable complexity. The former are similar to those which occur in the photolytic decomposition. Reactions of ionic species131-136 will not be discussed in this article. 

A yellow solution is formed when nitrous acid is added to thiosulphate ion in water84. This is believed to be due to the formation of nitrosyl thiosulphate [O3SSNOI, although this has not been isolated and even in solution decomposition is fairly rapid. The equilibrium constant for its formation Wxno is 1.66 x 107 dm6 mol 2 at 25 °C and the UV-visible absorption spectrum is very similar to that of other S -nitroso compounds85. The rate constant for its formation is very large and is believed to represent a diffusion controlled process. Thiosulphate ion does appear to catalyse nitrosation but, over the range studied... 

A considerable amount of nitrous acid is present in the spent acid. /J-Nitroethyl nitrate is feebly acidic and dissolves in dilute alkali solutions with a yellow color. It is not sufficiently stable for use in commercial explosives. On digestion with warm water or on slow distillation with steam it undergoes a decomposition or sort of hydrolysis whereby nitrous acid and other materials are produced. Numerous patents have been issued for processes of procuring pure nitroglycol from the Kekule oil. One hundred parts of the last-named material yield about 40 parts of nitroglycol, and the economic success of the Process depends upon the recovery of valuable by-products from the 0-nitroethyl nitrate which is destroyed. ... 

There are many modifications—e.g. in F. Valentiner s process in which the decomposition of the nitrate is carried out under reduced press., and accordingly at a reduced temp., so as to avoid thermal decomposition of the nitric acid. This process was modified by H. Fischer, and A. Hough. According to W. Mason, the best results are obtained with the press, reduced from 25 to 15 mm. of mercury. The formation of nitrous acid, which is especially to be avoided in this process, is unconnected with the use of an iron pot but is caused by over-heating with careful firing, even with sulphuric acid of sp. gr. 1-75, the nitrous acid content may be as low as 0-2 per cent. An undesirable acceleration of the distillation accompanied by frothing often occurs, when about 30 per cent, of the nitric acid distillation has occurred, is due to the loss of water from the acid sulphate. A yield of 97-99 per cent, nitric acid is obtained by this method. There are also continuous systems... 

The reduced iron atoms of complex C, being inert to dioxygen, are readily oxidized by nitrous oxide into complex D to give adsorbed species of a-oxygen, Oa. As Figure 7.3 shows, the reversible redox transition Fc" <-> Fe provides the catalytic activity of FeZSM-5 both the oxidation cycle due to the oxygen transfer from N20 to a substrate and the decomposition cycle of N20 into N2 and 02 due to recombination of a-oxygen into the gas phase. The decomposition is an environmentally important process, and FeZSM-5 zeolites are considered to be the best catalysts for this reaction (see review [117] and references therein). 

Nitrous oxide is a linear nonsymmetrical molecule, NNO. Its photochemistry has been investigated many times37. The known products of the photochemical decomposition of N20 are N2, 02, and NO. Two primary processes may be visualized... 

A safer option may be to destroy the nitrous oxide after the absorption section, in the tail gases of the nitric acid plant. The process conditions are less severe, and NOx decomposition is not a problem221. 

Ammonium nitrate decomposes in two ways. Controlled decomposition with careful heating is the commercial process for producing nitrous oxide ... 

The first 1,2,3-thiadiazole synthesized, 1,2,3-benzothiadiazole, was prepared by diazotiz-ation of o-aminothiophenol with nitrous acid (equation 31) (B-61MI42400), and recently sodium nitrite-acetic acid has been substituted for nitrous acid (B-79MI42400),. Another modification, thermal decomposition of diazonium acetate (34), affords benzothiadiazole in good yield in contrast to the variable yields usually experienced in the diazotization of o-aminothiophenols (equation 32) (78SST(5)43l). Benzothiadiazoles are also available directly from aromatic amines (equation 33) (70JCS(C)2250). Sulfur monochloride reacts with the amine to form a benzothiazothiolium salt which reacts with nitrous acid to yield a chlorinated 1,2,3-benzothiadiazole (35). This process, depending on the aromatic ring substitution, may afford a number of products, and yields are variable. 

The products of the primary modes of dissociation in the photochemical decomposition of nitrous oxide are 0, N, N2, and NO in their ground states, as well as in their excited states, depending on the exciting wavelength. Subsequent processes are, however, very complex and no... 

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