Industrial nitration processes

Since the nitrations of interest to us are exothermic reactions that produce expl substances it is obvious that safety is an important consideration in any laboratory nitration and even more so in an industrial nitration process, in the... 

Additionally, under the Europa Environmental Directive 96/82/EC called Saveso II Directive" on the control of major accident hazard involving dangerous substances, information on dangerous substances is inventoried. Of the several interesting literature databases, a process chemist would find the literature references from www.rxeforum.com very useful for the kinetic models and calorimetric data for product development and validation very useful while considering the thermal stability of the reactions. The article The Identification of Decomposition Products in as Industrial Nitration Process under Thermal Runaway Conditions " would have been very useful in developing the direct nitration process. 

Ma.nufa.cture. The batch nitration processes for nitrocellulose have included the pot process, the centrifugal process, the Thompson displacement process, and the mechanical dipper process. Semicontinuous nitration processes are also widely used for military and industrial grades. 

Manufacture and Processing. Mononitrotoluenes are produced by the nitration of toluene in a manner similar to that described for nitrobenzene. The presence of the methyl group on the aromatic ring faciUtates the nitration of toluene, as compared to that of benzene, and increases the ease of oxidation which results in undesirable by-products. Thus the nitration of toluene generally is carried out at lower temperatures than the nitration of benzene to minimize oxidative side reactions. Because toluene nitrates at a faster rate than benzene, the milder conditions also reduce the formation of dinitrotoluenes. Toluene is less soluble than benzene in the acid phase, thus vigorous agitation of the reaction mixture is necessary to maximize the interfacial area of the two phases and the mass transfer of the reactants. The rate of a typical industrial nitration can be modeled in terms of a fast reaction taking place in a zone in the aqueous phase adjacent to the interface where the reaction is diffusion controlled. 

Nitration has been described as the most widespread and powerfully destructive industrial unit process operation [10]. 

The appropriate mixed acid compns for the nitration processes that produce militarily and industrially important expls will be described in Sections V VI. Typical MA compns for aromatic nitrations contain 110 to 200% nitric acid over the stoichiometric requirement. For the nitration of toluene to MNT DNT, a typical MA compn in round figures is 30% HN03,60% H2S04, 10% H20. For the nitration of DNT to TNT the MA contains no water and is approx 20% HN03, 80% H2S04... 

These three steps all produce significant amounts of waste. First, as discussed earlier, the nitration process results in the production of spent sulfuric acid. In the past the company had been able to sell much of this material to the coke and steel industries but declining demand meant that the acid now required disposing of, at additional cost. At the time green catalytic nitration technology was becoming available with clay, zeolite and lanthanide catalysts all providing possible alternatives to the use of sulfuric acid (see below). Improved selectivity to the desired para-isomer is an added benefit of some of these catalytic systems. However on the... 

Karl Bosch (1874-1940) and Alwin Mittasch (1869-1953) of Badische Anilin- und Soda-Fabrik eliminated the nitrate shortage that occurred after the British sea blockade effectively cut off the nitrate supply from Chile. By May of 1915, they had successfully developed at their Oppau Plant an industrial-scale process for oxidizing ammonia. Their process converted the large quantities of synthetic ammonia produced by the Haber process to nitric acid and other nitrates that were essential for fertilizers and explosives. (10)... 

Accident statistics formerly showed nitration as the most widespread and powerfully destructive industrial unit process operation (it has been overtaken by polymerisation). This is because nitric acid can, under certain conditions, effect complete and highly exothermal conversion of organic molecules to gases, the reactions often being capable of acceleration to deflagration or detonation. Case histories are described and safety aspects of continuous nitration processes are discussed in detail [1]. Of the 25 chapters of the book [2], each a paper presented at the symposium on Advances in Industrial and Laboratory Nitrations at Philadelphia in 1975, 3 deal with safety aspects of nitration Ch. 8, Hanson, C. etal., Side Reactions during Aromatic Nitration, Ch. 22, Biasutti, G. S.,... 

This example analyzes lab research of yields in a nitration process, which gives the basic product for medicine and dye industries. Three factors assumed to have effects on yield in the nitration process have been researched ... 

In the TNT manufg industry, the acid recovery house is equipped to operate a separate process called "denitration or "acid recovery . During the mono-nitration process, the monomix acid becomes progressively weaker in HNOa and richer in water, so that the mono-waste acid resulting after nitration is complete contains only 4% of actual HNOa. The mono-waste acid also contains such a high percentage of water that it cannot be fortified economically as can the bi-and tri-spent acids. It is necessary, therefore, for economic reasons to recover H2S04 HNOa by distillation... 

Fig. 22.20. Ammonium nitrate process sketch. (Courtesy of Wiley-VCH. 295. Zapp, K.H.., Ammonium Compounds, in Ullmann s Encyclopedia of Industrial Chemistry, Wiley-VCH Verlag GmbH Co., Weinheim, Germany, June 15, 2000.)...

The method of manufacture of nitroform from acetylene found as early as 1900 by Baschieri (Voi. I, p. 587) was described by Orton and McKie [141]. It became possible to convert one of the carbons of acetylene to nitroform through a mercury catalysed oxidation-nitration process with nitric acid. Nitroform is an intermediate product of nitration and yields tetranitromethane under the action of excess nitric acid (Vol. I, p. S94). The method was developed during World War II by Schultheiss I42] and Schimmelschmidt 143 on a large laboratory scale with the atm of producing tetranitromethane. l ater the industrial scale method for the manufacture of nitroform was created by Wctter-holm [I44 (and is described below). 

Of the various indirect processes for the manufacture of highly concentrated acid only two are industrially important the sulfuric acid process and the magnesium nitrate process. 

The manufacture of concentrated nitric acid (98—99%) can be done by two methods, direct and indirect. The indirect method, mainly used in the United States, is performed industrially by two different systems, the sulfuric acid and magnesium nitrate processes. Both processes involve the dehydration of nitric acid with concentrated H2S04 or Mg(N03)2. The sulfuric acid process has acute corrosion problems. This process utilizes azeotropic rectification to produce concentrated nitric acid. 

American Cyanamid has industrialized a process which limits the temperature rise. To do this, it uses a large excess of add (14 times the weight of benzene to be nitrated, instead of 3 in the conventional method). Under these conditions, the add absorbs the heat generated by the reaction, and the temperature does not exceed 145°C, thus preventing undesirable side conversions, but increasing the reaction rate in comparison with the conventional process. Before recycling, moreover, the add is concentrated at this temperature, with a slight additional heat input... 

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