Nitrobenzene adiabatic nitration

In the last few years several modifications to the traditional mixed acid nitration procedure have been reported. An adiabatic nitration process was developed for the production of nitrobenzene (9). This method eliminated the need to remove the heat of reaction by excessive cooling. The excess heat can be used in the sulfuric acid reconcentration step. An additional advantage of this method is the reduction in reaction times to 0.5—7.5 minutes. 

This example involves a continuous adiabatic nitration process for the manufacture of mono-nitrobenzene (MNB) [215] by the reaction of benzene with nitric acid in a CSTR system. The process is designed to be inherently safe. No external cooling is used, but the reaction mass is heated by the reaction itself to a temperature level controlled by the amount of sulfuric add-water mixture circulating through the system. This acid actually acts as both a heat sink and as a nitration enhancer. If the sulfuric add pumps fail, the nitric add and benzene pumps are automatically shut off. 

Nitrobenzene is made by three processes direct nitration, dehydrating nitration and adiabatic nitration. The first process involves the direct nitration of benzene using a mixture of nitric acid and sulfuric acid46,258. 

Nitrobenzene (Aniline). The U.S. nitrobenzene production was about 2 billion lb in 1999. Two types of manufacturing processes were used the direct nitration and the adiabatic nitration process. In the direct nitration system, benzene is mixed with a mixture of nitric/ sulfuric acid. The reaction can be carried out in either a batch or a continuous system. Those reactors require a cooling system to keep it at constant temperature. It also requires a separate system for sulfuric acid reconcentration. In the adiabatic process, water is flashed off under vacuum before the sulfuric acid/nitrobenzene separation. The advantage of the adiabatic process is to eliminate a separated sulfuric acid reconcentration unit. This also will provide a better heat integration. Recently, the disposal of nitrophenols has become a major issue for aniline manufacture. Small amounts of nitrophenols are always made during the benzene... 

Nitrobenzene is produced by the nitration of benzene in a mixed nitrating (nitric/sulfuric) acid solution, using either the direct nitration process or adiabatic nitration. The first process involves the direct nitration of benzene in a batch or a continuous reactor. In the adiabatic process, an excess of benzene and a mixture of nitric and sulfuric acid are added to a series of reactors. Product nitrobenzene and dilute sulfuric acid are separated, water is flashed off under vacuum, and the sulfuric acid is recycled. 

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