OXIDATION SYSTEM WITH SECONDARY REACTOR FOR SIDE STREAM Russian patent published in 2016 - IPC C07C51/265 C07C63/26 B01J8/22 B01J10/00 

FIELD: chemistry.

SUBSTANCE: invention relates to an improved system for producing terephthalic acid by contacting a suspension containing p-xylene with a gas-phase oxidant containing air, wherein the said system includes: a primary oxidation reactor having the first suspension outlet, and the secondary oxidation reactor having a suspension inlet, the second suspension outlet, a normally lower oxidant inlet and a normally upper oxidant inlet, wherein the said suspension inlet is located downstream in hydraulic connection with the said first suspension outlet, wherein the said secondary oxidation reactor is a secondary reaction zone, having the maximum length Ls, wherein the distance to the said normally lower oxidant inlet from the bottom of the said secondary reaction zone is not less than 0.5 Ls, wherein the distance to the said upper oxidant inlet from the bottom of the said secondary reaction zone is at least 0.5 Ls; and where the primary oxidation reactor is a bubble column reactor and the said secondary oxidation reactor is a bubble column reactor. The invention also relates to a method of producing a terephthalic acid composition, the said method comprising: (a) feeding the first multiphase reaction medium, containing the compound to be oxidised, for oxidation into the primary reaction zone located in the primary oxidation reactor, as a result of which the first suspension is obtained, wherein the compound to be oxidised contains p-xylene; and (b) contacting at least a portion of the said first suspension with a gas-phase oxidant in the secondary reaction zone located in the secondary oxidation reactor, as a result of which a second suspension is obtained, wherein the gas-phase oxidant contains air, wherein the said secondary reaction zone has the maximum length of Ls, wherein the first portion of the said gas-phase oxidant enters the said secondary reaction zone in the first oxidant inlet region at a distance from the bottom of the said secondary reaction zone of at least 0.5 Ls, wherein the said first portion of the said gas-phase oxidant is 5-49% of the full volume of the said gas-phase oxidant fed into the said secondary reaction zone, and the said primary oxidation reactor is a bubble column reactor, wherein the said secondary oxidation reactor is a bubble column reactor and where the said secondary reaction zone comprises the second oxidant inlet region.

EFFECT: apparatus and method can enable reducing the content of oxygen in the entire post-oxidation reactor.

15 cl, 6 dwg