Phosgene reactor

Fig. 6. Schematic of hexamethylene diamine phosgenation process A, HMD A tanks B, phosgene solution tanks C, phosgenation reactor D, secondary...

Figure 10-9 Original design of phosgene reactor before informal safety review.

Figure 10-11 Final design of phosgene reactor after informal safety review.

Figure 17.34. Temperature and conversion profiles in a water-cooled shell-and-tube phosgene reactor, 2-in. tubes loaded with carbon catalyst, equimolal CO and Cl2.

Most of the excess phosgene and hydrochloric arid formed, as well as about O per cent of the monochloro benzene, are removed at the top of the phosgenation reactors and recycled. The liquid stream from the final reactor is sent to a purification train comprising the following main operations ... 

The historical direct reaction route, which utilised phosgenation of a solution of BPA in pyridine, proved inefficient commercially because of the need for massive pyridine recycle. Calcium hydroxide was used as an HCl scavenger for a period of time. In the historical transesterification process, BPA and diphenyl carbonate are heated in the melt in the presence of a catalyst, driving off by-product phenol, which is recycled to diphenyl carbonate. Using a series of reactors providing higher heat and vacuum, the product polymer was eventually produced as a neat melt. 

An equimolar mixture of carbon monoxide and chlorine reacts at 500 K under a slight positive pressure. The reaction is extremely exothermic (Ai/gQQp. = —109.7 kJ or —26.22 kcal), and heat removal is the limiting factor in reactor design. Phosgene (qv) is often produced on-site for use in the manufacture of toluene diisocyanate (see Amines, aromatic-diaminotoluenes Isocyanates, organic). 

DuPont s phosgene synthesis in a micro reactor BASE S vitamin precursor synthesis developments in the bio field prognosis on market volume in 2000 [227]. 

Ajmera, S.K., Losey, M.W., Jensen, K.F., Schmidt, M.A. (2001) Microfabricated Packed-Bed Reactor for Phosgene Synthesis. AIChE Journal, 47, 1639-1647. 

Apart from chlorine (without or with carbon), carbon tetrachloride, phosgene, hydrogen chloride, and sulfur dioxide-chlorine mixtures, some of the metal chlorides can also function as chlorinating agents. The chlorinating action of metal chlorides is dramatically illustrated by the behavior of the silica lining in reactors used for the chlorination of titanium dioxide and beryllium dioxide. 

At the start of interfacial polymerization, bisphenol A is dissolved in methylene chloride, then introduced into a reactor. Phosgene is injected into the reactor as a liquefied gas together with an aqueous solution of sodium hydroxide. The methylene chloride and the aqueous solutions are immiscible polymerization occurs at the interface between them. The reactants are combined in a rapidly stirred reactor as shown in Fig. 20.7. The sodium hydroxide neutralizes the hydrochloric acid that is generated by polymerization, while the organic phase serves as a solvent for the polymer. The organic phase is separated and washed to remove traces of the base or salts after which the solvent is removed. 

The aniline was being phosgenated in toluene as solvent, the reaction ran wild and ejected more than 3 tonnes of reactor contents. This is believed to have been due to water contamination, possibly as ice. An initial charge of only part of the phosgene failed to show the exotherm anticipated if water was present, however this may not have been enough, nor was the thermocouple immersed in the solvent. See Diprotium monoxide... 

Consider the laboratory reactor system shown in Figure 10-9. This system is designed to react phosgene (COCl2) with aniline to produce isocyanate and HC1. The reaction is shown in Figure 10-10. The isocyanate is used for the production of foams and plastics. 

In the process shown in Figure 10-9 the phosgene is fed from the container through a valve into a fritted glass bubbler in the reactor. The reflux condenser condenses aniline vapors and returns them to the reactor. A caustic scrubber is used to remove the phosgene and HC1 vapors from the exit vent stream. The complete process is contained in a hood. 

Describe an informal safety review process for using a cylinder of phosgene to charge gaseous phosgene to a reactor. Review up to the reactor only. 

A reactor charged with the step 4 product, 75 ml of CH2CI2, and 10.8 ml of pyridine was treated with dropwise addition of 22.5 ml of 1.94 M solution of phosgene in toluene (43.6 mmol) at ambient temperature. The mixture stirred for 3.5 hours and was then diluted with 500 ml of CH2C12 and transferred into a separatory funnel. The mixture was extracted with 0.2 M hydrochloric acid, the organic phase dried over MgS04, concentrated to 150 ml, and precipitated by pouring into 750 ml of hexane and the product isolated. 

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