Views:1 Author:Site Editor Publish Time: 2022-01-05 Origin:Site
The ketorenazone method, also known as Bergbau-Bayer-Whiffen method, was developed in the 1960s. It was first patented by Bergbau-Farsching, a subsidiary of the German Coal Mining Association. The process was improved by Bayer and Whiffen & Sons. Respectively, in the mid 1970s, large-scale industrialization and rapid development, is actually an improvement of the original Lacey law.
The ketone nitrogen method consists of the following steps:
① In the presence of aliphatic ketones, hydrazone, hydrazone or hydrazone can be obtained by oxidizing ammonia with NaOCl. The composition of the product depends on the pH value of the system, ketone ratio and reaction conditions. In the presence of excess ketone, hydrazone and isohydrazone can be converted into ketone - azo.
② After the oxidant is completely consumed, the intermediate is concentrated and then hydrolyzed into hydrazine and hydrazine salt. Hydrazine hydrate solution was synthesized from ammonia water and NaOCl solution at the temperature of 4MPa and 140℃. The excess ammonia was removed by air extraction, and then the finished hydrazine hydrate was obtained by evaporation desalting distillation.
In The German Bayer process, Cl2 and dilute NaOH solution are continuously reacted in a NaOCl reactor to generate NaOCl and NaCl. NaOCl is reacted with ammonia and acetone in a ketonitrification reactor at 30-40℃ and 0.2mpa. Under the condition of n(NaClO) : N (acetone) : N (ammonia)= 1:2:20 and good mixture, the yield of ketone nitrogen can reach 98%(calculated by chlorine). When methyl ethyl ketone was used, the process consumption ration was 320kg/t pure hydrazine, but when pentanone was used, it could be reduced to 100kg/t pure hydrazine, and the overall yield of this method was 90%.
The Japanese process is in the presence of ketone, by the reaction of Ca(ClO)2 and ammonia to make ketone, and then through hydrolysis to get hydrazine hydrate calcium ketone.
In this method, ammonia and ketone can be recovered and reused. The waste salt water containing CaCl2 was treated with Na2CO3 to obtain CaCO3 precipitation, which was converted to Ca(OH) 2 after high temperature calcination and water dissolution.
Therefore, the method has the advantages of high utilization rate of raw materials and less by-products.
In view of the shortcomings of Bayer process, such as large amount of ammonia and low concentration of hydrazine in hydrolysate, Southwest Research Institute of Chemical Industry in China developed a catalytic oxidation process for hydrazine production:
The rare earth, silica gel and hypochlorite complex with code name CL-5 was used as the catalyst. The amount of catalyst was 0.1%-4% of the mass of NaOCl, and the molar ratio of butanone, ammonia and NaOCl was (2-8) : (2-12) : 1. The butanone was separated from water, and hydrazine hydrate was obtained after hydrolysis.
In this method, the yield of butanone nitridation was increased by 8%-12% under the condition of reducing the amount of ammonia, the hydrolysis efficiency of butanone nitridation was more than 99%, and the yield of hydrazine hydrate was more than 98%, which greatly reduced the energy consumption.