METHOD AND APPARATUS FOR CONTINUOUS PRODUCTION OF PARA-AMINOPHENOL BY REDUCTION OF PARA-NITROSOPHENOL WITH AMMONIUM SULPHIDE Russian patent published in 2024 - IPC C07C213/02 C07C215/76 C07C213/10 

FIELD: various technological processes; chemistry.

SUBSTANCE: present invention relates to chemical engineering, specifically to a method for continuous production of p-aminophenol by reduction of p-nitrosophenol with ammonium sulphide, as well as to an apparatus for realizing said method. Method includes stages a–g. At step (a), a solution of p-nitrosophenol in aqueous ammonia solution is prepared, at step (b), an aqueous solution of ammonium sulphide is provided. At step (c), solutions from step (a) and (b) with flow ratio corresponding to molar ratio of p-nitrosophenol to (NH₄)₂S from 1:1.5 to 1:2.5, simultaneously, it is continuously fed into a reduction reactor with an inert atmosphere while stirring to form a reaction mixture. Then, at step (d), a portion of the reaction mixture is discharged by gravity from the reduction reactor into the suspension concentration reactor equipped with a mixer to form a reaction mixture for concentrating the suspension of p-aminophenol. At the same time in the concentration reactor the temperature is maintained at 15–20 °C. At step (e), a portion of the reaction mixture is discharged by gravity from the suspension concentration reactor into a continuous centrifuge; at step (f), solid p-aminophenol is separated and washed with water. At step (g), p-aminophenol is discharged from a continuous centrifuge to obtain the finished product. Ratio of the maximum volumes of the reduction reaction mixture at step (c) and the reaction mixture for concentrating the suspension at step (d) ranges from 1:5 to 1:10.

EFFECT: providing a productive method for continuous production of a stable, homogeneous target product, with simple hardware and technological design, using readily available reagents and solvents, as well as profitable use of the generated wastes.

17 cl, 1 dwg, 1 tbl, 3 ex