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° 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 present invention relates to an improved process for preparing mononitrobenzene. More specifically, it relates to an adiabatic nitration process that will minimize the formation of undesired by-products. Background of the invention [0002] Industrially, mononitrobenzene is produced by several adiabatic nitration techniques. Adiabatic nitrification was first introduced by Castner as described in US 2,256,999. The adiabatic nitration of benzene has replaced the previously used energy-intensive isothermal nitration process. [0003] In the late 1970s, Alexanderson et al. proposed varying the composition and temperature limits of Castner's adiabatic nitration process, resulting in a commercially useful process, as described in US 4,021,498 and US 4,091,042. US 4,021,498 describes a process for the preparation of mononitrobenzene using a mixed acid with a strength of nitric acid of 5-8.5% by weight, a strength of sulfuric acid of 60-70% by weight an...

AI Technical Summary

Problems solved by technology

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

Images