Research For The Preparation Of DSD Acid By Liquid Phase Continuous Hydrogenation

As the substitution of benzidine dye,stilbene dye is more and more accepted by market with its hypotoxicity,4,4 '-diamino stilbene-2,2'-disulfonic acid(DSD acid)is the main intermediate for the preparation of stilbene dye.At present,a process of sulfonation of PNT,oxidation with air,and reduction with iron power is mainly used to prepare DSD acid.In this study,the process of ircon powder reduction is replaced by liquid phase continuous hydrogenation.The laboratory research of the yield was 91%,and the pilot was 89%.The cost of the liquid phase continuous hydrogenation method is similar to the process of iron powder reduction,and the discharge amount of “waste water” is declined by 40% compared to the process of iron powder reduction.The green production for the preparation of DSD acid is achieved by using of this research.