Adiabatic process for making mononitrobenzene

Abstract

An adiabatic process for making mononitrobenzene by the nitration of benzene which minimizes the formation of nitrophenols and dinitrobenzene by-products. The process uses a mixed acid having less than 3 wt% nitric acid, 55 to 80 wt% sulfuric acid, and water. The initial temperature of the mixed acid is in the range of 60 to 96 DEG C. The nitration reaction is complete in about 300 seconds and produces less than 1,200 ppm nitrophenols and less than about 80 ppm dinitrobenzene. The reaction can be carried out in a plug-flow or a stirred pot reactor, or a combination of such reactors.

Description

Technical field [0001] The invention relates to an improved process for preparing mononitrobenzene. More specifically, it relates to an adiabatic nitrification process that will minimize the formation of undesirable by-products. Background of the invention [0002] In industry, mononitrobenzene is produced using several adiabatic nitration technologies. Adiabatic nitrification was first introduced by Castner, as described in US 2,256,999. The adiabatic nitrification of benzene has replaced the previously used isothermal nitrification process with high energy consumption. [0003] In the late 1970s, Alexanderson et al. proposed to change the composition and temperature limit of Castner's adiabatic nitrification process, resulting in a commercially useful process, which is described in US 4,021,498 and US 4,091,042. US 4,021,498 describes a process for preparing mononitrobenzene using a mixed acid with nitric acid strength of 5-8.5 wt%, sulfuric acid strength of 60-70 wt%, and wat...

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Problems solved by technology

The operating costs and capital investment required to remove and dispose of these by-products are significant

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