Nobel process

Nobel invented a radically new design of nitrator for the manufacture of nitroglycerine. Originally it was made of sheet lead and equipped with a cooling coil supplied with water, (Fig. 15, p. 65) and later a water-cooled jacket made of wood was added (Fig. 28). In later versions of the Nobel nitrator the cooling jacket was omitted in favour of a four-fold cooling coil with which it was easier to control the nitration temperature. 

Glycerine is run into the nitrator through a funnel in the cover. The part of pipe containing (5) and (6) is joined by means of a hose to the stiff pipe for feeding glycerine. 

During nitration the temperature inside the nitrator is measured by thermometers (7) and (5) and is controlled by the operator who reduces the flow of glycerine if the temperature rises too high. Acid vapours together with the air used for mixing 

After-separators wherein the waste acid is stored, are open tanks of lead. Nitroglycerine that collects on the surface is removed every few hours with an aluminium ladle, and is to be poured into the preliminary drowning tank situated in the same room. 

After the primary washing nitroglycerine is transferred to the final washing by the usual methods. The solutions and water remaining after washing are transferred to the labyrinth. The flow-sheet is shown in Fig. 30 and a complete view of the plant is given in Fig. 31. 

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Eigure 3 is a flow diagram which gives an example of the commercial practice of the Dynamit Nobel process (73). -Xylene, air, and catalyst are fed continuously to the oxidation reactor where they are joined with recycle methyl -toluate. Typically, the catalyst is a cobalt salt, but cobalt and manganese are also used in combination. Titanium or other expensive metallurgy is not required because bromine and acetic acid are not used. The oxidation reactor is maintained at 140—180°C and 500—800 kPa (5—8 atm). The heat of reaction is removed by vaporization of water and excess -xylene these are condensed, water is separated, and -xylene is returned continuously (72,74). Cooling coils can also be used (70). 

As compared with the Nobel process for nitroglycerine manufacture certain innovations were introduced in this method, namely ... 

The method of Nathan, Thomson, and Rintoul was used only in a few factories and generally on the Continent a combined process incorporating the advantages of the Nobel process with those of the Nathan, Thomson and Rintoul process was used. 

This is one of the most important industrial oxidation processes. Terephthalic acid (TPA) is mostly used for the manufacture of polyester fibers, films and plastics, and its world production capacity reaches 8 Mt/year. Two major processes have been developed. The Amoco-Mid Century process produces terephthalic acid by the one-step oxidation of p-xylene in acetic acid, whereas the Dynamit Nobel process yields dimethyl terephthalate in several steps and in the absence of solvent.83,84,86... 

The Dynamit Nobel process produces dimethyl terephthalate (DMT) by a complicated series of oxidation and esterification stages (equation 241).83,84,86 In the oxidation section, p-xylene is oxidized at 150°C and 6 atm without solvent and in the presence of cobalt octoate to TPA and p-toluic acid. These oxidation products are sent to another reactor for esterification by methanol at 250 °C and 30 atm. Fiber grade DMT is purified by several recrystallizations, and monoesters are recycled to the oxidation reactor. The overall yield in DMT is about 80%, which is lower than in the Amoco process. However, this process is competitive because it is not corrosive and requires lower investments. It provides high-quality fiber-grade dimethyl terephthalate. 

Batch methods of nitroglycerine manufacture Old process Nobel process... 

Bofors-Nobel- process Nitrobenzene atmos. 60 Benzene/ HNO3/ H2SO4 Nitration can also be carried out batch-wise... 

Michelin Research had earlier developed a process using a mixture of phosphoric and formic acids, also for tire yams. The Akzo-Nobel process, based on phosphoric acid alone, was felt to give easier solvent recovery. A process using phosphoric acid alone (105) emerged from Michelin Research in March 1996. 

The two procedures primarily used for continuous nitration are the semicontinuous method developed by Bofors-Nobel Chematur of Sweden and the continuous method of Hercules Powder Co. in the United States. The latter process, which uses a multiple cascade system for nitration and a continuous wringing operation, increases safety, reduces the personnel involved, provides a substantial reduction in pollutants, and increases the uniformity of the product. The cellulose is automatically and continuously fed into the first of a series of pots at a controlled rate. It falls into the slurry of acid and nitrocellulose and is submerged immediately by a turbine-type agitator. The acid is deflvered to the pots from tanks at a rate controlled by appropriate instmmentation based on the desired acid to cellulose ratio. The slurry flows successively by gravity from the first to the last of the nitration vessels through under- and overflow weirs to ensure adequate retention time during nitration. The overflow from the last pot is fully nitrated cellulose. 

RigidPoly(vinylchloride) Foam. The techniques that have been used to produce rigid vinyl foams are similar to those for the manufacture of flexible PVC foams. The two processes that have reached commercial importance for the manufacture of rigid vinyl foams (246) are the Dynamit-Nobel extmsion process and the Kleber-Colombes Polyplastique process for producing cross-linked grafted PVC foams from isocyanate-modified PVC in a two-stage mol ding process. 

The Dynamit-Nobel extmsion process (252) utilizes a volatile plasticizer such as acetone which is injected into the decompression section of a two-stage screw and is uniformly dispersed in the vinyl resin containing a stabilizer. The resulting PVC foam has low density and closed cells. 

Herm/es/Djnamit JS obe/Process. On a worldwide basis, the Hercules Inc./Dynamit Nobel AG process is the dorninant technology for the production of dimethyl terephthalate the chemistry was patented in the 1950s (67—69). Modifications in commercial practice have occurred over the years, with several variations being practiced commercially (70—72). The reaction to dimethyl terephthalate involves four steps, which alternate between liquid-phase oxidation and liquid-phase esterification. Two reactors are used. Eirst, -xylene is oxidized with air to -toluic acid in the oxidation reactor, and the contents are then sent to the second reactor for esterification with methanol to methyl -toluate. The toluate is isolated by distillation and returned to the first reactor where it is further oxidized to monomethyl terephthalate, which is then esterified in the second reactor to dimethyl terephthalate. 

This melt-processable homopolymer was first introduced in 1961 as Kynar by the Pennsalt Chemical Corporation (the company name being subsequently changed to Pennwalt). Other companies now manufacturing similar polymers are Dynamit Nobel (Dyflor), Kureha (KF), Solvay (Solef) and Atochem (Foraflon). 

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