METHOD FOR THE CONTINUOUS PRODUCTION OF NITROBENZENE

摘要

The present invention relates to a method for producing nitrobenzene, in which the waste gas streams accruing in the process and containing benzene and (traces of) nitrobenzene, possibly low- and medium-boiling components, possibly non-condensable gases and possibly water, optionally after removal of nitrogen oxides, are scrubbed in an absorption column with nitrobenzene, which comprises only very small amounts (maximum 50 ppm) of benzene and is distributed by means of a liquid distributor at a rate of 50 to 200 drip points per square metre, preferably 60 to 120 drip points per square metre, wherein (i) a liquid stream containing benzene and nitrobenzene, possibly organic low- and medium-boiling components and additionally containing sulfuric acid if sulfuric acid is used as the scrubbing agent and (ii) waste gas depleted in benzene and possibly in organic low- and medium-boiling components are obtained. A waste gas purified by the method according to the invention is particularly suitable for burning in a thermal exhaust air treatment process.

主权项

1. A method for producing nitrobenzene, comprising,
a) nitrating benzene with nitric acid or mixtures of nitric acid and sulfuric acid and subsequent phase separation into an aqueous phase and crude nitrobenzene, b) scrubbing the crude nitrobenzene from step a) with an aqueous scrubbing solution in at least three scrubbing stages, each stage followed by separation of the scrubbing solution, wherein following separation of the scrubbing solution used in the final scrubbing stage a pre-purified nitrobenzene mixture is obtained which comprises at least benzene and water in addition to nitrobenzene, c) removing benzene and water from the pre-purified nitrobenzene mixture from step b) by distillation in a distillation apparatus to give purified nitrobenzene,wherein waste gas streams accrue in steps a) to c) which contain benzene and nitrobenzene, and
d) scrubbing the waste gas streams countercurrently in an absorption column with nitrobenzene, which has a benzene content of <50 ppm, relative to the total mass of nitrobenzene, and is distributed by means of a liquid distributor at a rate of 50 to 200 drip points per square meter, wherein (i) a liquid stream containing benzene and nitrobenzene and (ii) a nitrobenzene-depleted waste gas are obtained.