Benzene → Nitrobenzene

A sulfuric acid stream (11), a nitric acid stream (12) and a benzene stream (13) are fed to a reactor (1). After complete reaction of the nitric acid with the benzene to form nitrobenzene under adiabatic reaction control, the reaction product (14), which is now at a temperature of approx. 130° C., is fed to a phase separation unit (2) in which the reaction product (14) breaks down into an organic phase ((15),=crude nitrobenzene, containing benzene in addition to nitrobenzene) and an aqueous phase ((16),=waste acid, containing small proportions of nitrobenzene and benzene in addition to sulfuric acid). The aqueous phase (16) comprising mainly sulfuric acid is subjected to an instantaneous evaporation of water in the evaporator (3) by a sudden reduction in pressure and concentrated in this way. The concentrated sulfuric acid (17) is stored in the sulfuric acid tank (4) to be used again. Following separation in the phase separation unit the crude nitrobenzene (15) is cooled in the crude nitrobenzene cooling unit (5) and fed to the washing stage (6), which is made up of three types of washes, namely (i) an “acid wash” (see above), (ii) an alkaline wash with sodium hydroxide solution (using the procedure described in paragraphs [0008] to [0012] of EP 1 816 117 B1) and (iii) three neutral washes with steam condensate, with electrophoresis (cf. EP 1 816 117 B1) optionally being used in the last neutral wash. The stream of purified nitrobenzene (18) thus obtained, which has largely been freed from nitrophenols and salts, is heated again and freed in a distillation column (7) from water and benzene, which are separated off overhead (19), to produce dried pure nitrobenzene (20) which is stored in the tank (8).

ORD record

ord-33baaca925394222a7aa132bb11c02b6

Source dataset

uspto-grants-2015_04

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09012700B2