Benzene → Nitrobenzene

When the nitric acid has reacted completely with benzene under adiabatic conditions in the reactor (1) to give nitrobenzene and water, the reaction mixture (S4) thereby heated to about 135° C. (see the examples) is fed to a phase separator in the form of a decanter (2), in which the reaction mixture is separated into a phase of crude nitrobenzene (S5) and spent acid (S6). The spent acid (S6) is partially concentrated in a first evaporator (3) operated at 260 mbar. Also shown is a false air stream (S16), which is drawn into the first evaporator (3) by the vacuum therein. The vapour stream (S12) produced in the first evaporator (3), comprising water, sulfuric acid, nitrobenzene, benzene and aliphatic organic compounds, which are contained as impurities in the benzene stream (S1) for reaction, are condensed in a condenser (8) to a first liquid discharge stream (S13). The unevaporated, liquid discharge stream of the first evaporator (S7) is fed to the second evaporator (4), which is operated at a pressure of 74 mbar, and thereby concentrated to a concentration of 70% by mass sulfuric acid (S8). Also shown is a second false air stream (S15), which is drawn into the second evaporator (3) by the vacuum therein. For further use, the re-concentrated sulfuric acid (S8) is accordingly stored in a sulfuric acid tank (5). In the second evaporation of the spent acid there is obtained a vapour stream (S9) consisting substantially of water as well as residues of sulfuric acid, nitrobenzene and benzene, which is condensed in a condenser (6).

ORD record

ord-23166db5e2b144b0baae6bcb5afa3891

Source dataset

uspto-grants-2015_09

DOI

10.6084/m9.figshare.5104873.v1

Patent number

US09139508B2