Ammonium sulfate, decomposition

Dugger, G. L., Adams, J. B. and Bart, R., Ammonium sulfate decomposition . United States Atomic Energy Commission, RMO-2036 (1955). 

A question arises as to whether the formation of ammonium sulfate on the catalyst surface is possible at 400. a temperature jusi above that for ammonium sulfate decomposition. This is in principle possible according to the principle of capillary condensation in micropores ref. 2). It should be noted that pores of mordeniie zeolite range from 0,7 to 1.0 nm in radius. 

Diketene is a flammable Hquid with a flash point of 33°C and an autoignition temperature of 275°C. It decomposes rapidly above 98°C with slow decomposition occurring even at RT. The vapors are denser than air (relative density 2.9, air air = 1). The explosive limits in air are 2—11.7 vol % (135). In case of fire, water mist, light and stabilized foam, as well as powder of the potassium or ammonium sulfate-type should be used. Do not use basic extinguisher powders and do not add water to a closed container. 

The reaction is mn for several hours at temperatures typically below 100°C under a pressure of carbon monoxide to minimise formamide decomposition (73). Conversions of a-hydroxyisobutyramide are near 65% with selectivities to methyl a-hydroxyisobutyrate and formamide in excess of 99%. It is this step that is responsible for the elimination of the acid sludge stream characteristic of the conventional H2SO4—ACH processes. Because methyl formate, and not methanol, is used as the methylating agent, formamide is the co-product instead of ammonium sulfate. Formamide can be dehydrated to recover HCN for recycle to ACH generation. 

A.mmonium Sulfate—Sodium Chloride Process. Ammonium sulfate, a readily available by-product, has been much used to make ammonium chloride by a double decomposition reaction with sodium chloride. 

Manufacture. Historically, ammonium nitrate was manufactured by a double decomposition method using sodium nitrate and either ammonium sulfate or ammonium chloride. Modem commercial processes, however, rely almost exclusively on the neutralization of nitric acid (qv), produced from ammonia through catalyzed oxidation, with ammonia. Manufacturers commonly use onsite ammonia although some ammonium nitrate is made from purchased ammonia. SoHd product used as fertilizer has been the predominant form produced. However, sale of ammonium nitrate as a component in urea—ammonium nitrate Hquid fertilizer has grown to where about half the ammonium nitrate produced is actually marketed as a solution. 

Ammonium sulfate [7783-20-2], (NH 2 U4, is a white, soluble, crystalline salt having a formula wt of 132.14. The crystals have a rhombic stmcture d is 1.769. An important factor in the crystallization of ammonium sulfate is the sensitivity of its crystal habit and size to the presence of other components in the crystallizing solution. If heated in a closed system ammonium sulfate melts at 513 2° C (14) if heated in an open system, the salt begins to decompose at 100°C, giving ammonia and ammonium bisulfate [7803-63-6], NH HSO, which melts at 146.9°C. Above 300°C, decomposition becomes more extensive giving sulfur dioxide, sulfur trioxide, water, and nitrogen, in addition to ammonia. 

Potassium and ammonium dichromates are generally made from sodium dichromate by a crystallization process involving equivalent amounts of potassium chloride or ammonium sulfate. In each case the solubiHty relationships are favorable so that the desired dichromate can be separated on cooling, whereas the sodium chloride or sulfate crystallizes out on boiling. For certain uses, ammonium dichromate, which is low in alkaH salts, is required. This special salt may be prepared by the addition of ammonia to an aqueous solution of chromic acid. Ammonium dichromate must be dried with care, because decomposition starts at 185°C and becomes violent and self-sustaining at slightly higher temperatures. 

A number of manufacturers around the world are using the decomposition of ammonium dichromate to produce chrome oxide (eq. 5) (78). Generally, an excess of finely ground ammonium sulfate is mixed with sodium dichromate, and the dry mixture is heated to form chrome oxide and sodium sulfate, evolving nitrogen and steam. 

A direct attack on the oxazirane ring occurs with ferrous salts. Oxaziranes are decomposed by aqueous solutions of ferrous ammonium sulfate even at room temperature. The reaction follows a radical-chain mechanism because le.ss than stoichiometric amounts of the ferrous salt cause the decomposition, 2-icrt-Butyl-3-phenyloxazirane (9) and 1 equivalent of ferrous salt give ferf-butylbenzamide in 98%... 

From animal tissue, especially bovine lung and liver (e. g. autolysis of comminuted tissue parts, heating with ammonium sulfate in alkaline solution, filtration and acidification yield heparin as complex with protein, removal of fat with alcohol and treatment with trypsine for the purpose of decomposition of proteins, precipitation with alcohol and various purification methods). 

Aqueous solutions of ammonium sulfate and ammonium bisulfate were deposited on Fluoropore filters, placed in the direct insertion probe, and analyzed in the chemical ionization mode (H2O reagent) gas. The samples were heated from 100°C to 330 C at 15 C/minute. No sample ions were observed under these anlaysis conditions, even when several micrograms of ammonium salts were analyzed. The thermal decomposition of ammonium salts of sulfate has been the subject of many studies. (29,30) Some pathways include sulfuric acid production at one stage of the decomposition while others suggest ammonia, SO2 and SO3 are the products. None of these accurately simulate the conditions (temperature, pressure, gas flow) present in our chemical ionization source. However, no sulfuric acid ions (H3SO4+, etc.) were ob-served... 

Ammonium nitrate alternatively may be prepared by double decomposition reactions of ammonium salt with a nitrate salt e.g., ammonium sulfate and sodium nitrate ... 

Borazine, B3N3H6, was first prepared by thermolysis of the diborane ammonia adduct [(BH2)(NH3)2] [BH4] . More convenient procedures for the laboratory preparation of this important ring system in multigram quantities involve either (a) the decomposition of ammonia- borane [eqn (9.1)] or (b) the reaction between ammonium sulfate and sodium borohydride [eqn (9.2)]. The latter method provides a convenient and economical synthesis of borazine. 

By the double decomposition of ammonium sulfate and sodium nitrate in solution (NH4),St>4 + 2NaNO, - 2NH4NO, + Na,S04. This process, patented by Freeth and Cocksedge (Ref 13), was an economical one up to the time of the development of synthetic NH, and of HNO, by ammonia oxidation... 

Diazotization has been reported for all the pyrazolopyridines, and in some cases the salts have been isolated. A 7-aminopyrazolo[4,3-c]pyridine (191a) was converted to the corresponding hydroxy compound with sodium nitrite in hot glacial acetic acid.159 Analogous products were obtained from a 3-aminopyrazolo[3,4-b]-15 and 2-aminopyrazolo[l,5-a]pyridine.186 Decomposition of diazonium salts with hydrobromic acid afforded 3-bromo-pyrazolo[3,4-c]-u0 or -[4,3-bjpyridines111 deamination of 3-aminopyra-zolo[3,4-h]pyridines was achieved via treatment of the diazonium salts with hypophosphorous acid,10 titanous chloride,238 or ferrous ammonium sulfate.238 Kocevar et al.236 have made a detailed study of the reactions of the latter diazonium salt. 

Oxamide, This diamide is sparingly soluble in water and insoluble 111 various organic solvents. It melts at about 350°C, with accompanying decomposition. Because of the low solubility in water, the compound is granulated and used as a slow-release nitrogen fertilizer. Conventional nitrogen ferdlizers such as ammonium sulfate, urea, ammonium nitrate, and ammonium phosphate, are soluble in water, and thus are easily lost as... 

Ammonium Sulfate. Addition to the fused nitrite causes effervescence and ignition.3 Boron. Addition to the fused nitrite causes violent decomposition.4 Potassium Amide. Explosion occurs when mixture with potassium amide is heated under vacuum.5... 

A review of the decomposition temperature of possible sulfur compounds on the catalyst surface shows that the weight loss around 250 to 500 °C would represent the decomposition of ammonium sulfate(230 °C). Therefore, the TGA of an ammonium sulfate-impregnated catalyst containing 7.3wt% of sulfur was examined and it shows similar weight loss... 

Ammonium Sulfate. The colorless, crystalline ammonium sulfate cannot be melted at atmospheric pressure without decomposition at 508 K, releasing ammonia and forming NH4HSO4. After cleavage of water, ammonium bisulfate (NH4128207 is left. However, the ammonia vapor pressure of pure, anhydrous ammonium sulfate is effectively zero up to 350K. Above 573 K, decomposition yields N2, SO2, S03,and H2O in addition to ammonia. ... 

As discussed above, FSEC s S-NH3 cycle also utilizes decomposition of sulfuric acid as the endothermic step for the absorption of solar thermal heat and production of oxygen. However, high temperature concentration and decomposition of sulfur acid presents daunting materials of construction issues. Like the metal sulfate based TCWSCs, it is possible to modify the S-NH3 cycle and do without the decomposition of H2SO4. There are two ways to accomplish this. The first approach is to decompose ammonium sulfate produced in the hydrogen production step of the S-NH3 cycle (Reaction (111)) to a metal sulfate in the presence of a metal oxide catalyst. The second approach is to convert ammonium sulfate to metal pyrosulfate e.g. Zto 20i)-... 

Just as metal oxides can be used as catalysts for converting ammonium sulfate to metal sulfate, metal sulfates can also be employed for converting ammonium sulfate to ammonium pyrosulfate (( 114)28207)). Sulfur dioxide and oxygen are products of ammonium pyrosulfate decomposition. Thus, a second class of modified S-NH3 TCWSCs based on the M2S2O7-NH3 can be devised as follows ... 

Decomposition of metal oxide ammonium sulfate mixtures... 

Huang, C., Mohajeri, N., Muradov, N., and T-Raissi, A., Solar Thermocatalytic Decomposition of Ammonium Sulfate, Proc. of Solar 2007, Cleveland, Ohio, July 7 to 12,2007. 

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