Views:1 Author:Site Editor Publish Time: 2022-01-07 Origin:Site
This method is an innovation of ketone - nitrogen method in essence.
It was first developed by Bayer in Germany in the 1960s, and was industrialised on a large scale and developed rapidly in the mid-1970s.
In this method, ketone imine is generated by the reaction of butanone (methyl-ethyl ketone) and ammonia, and then oxidized to oxazizone with H2O2, and then ammoniated to methyl-ketone nitrile. The latter is hydrolyzed into hydrazine and ketone, and the unreacted ketone can be recycled after purification.
The key of ketone nitrogen process is the hydrolysis and fractionation of ketone nitrogen to extract hydrazine. In the reaction process, the mass fraction of hydrogen peroxide used for the reaction can be 70% aqueous solution; Ammonia can be either gaseous or liquid; Methyl ethyl ketone can be used in the reaction of industrial products, and then can be recycled, it should be guaranteed that the molar ratio of secondary butanol and methyl ethyl ketone contained in the best ≤0.03. Catalysts can be amides, ammonium salts, arsenic compounds or hydrazine. Amide can choose formamide, acetamide, ammonium salt can choose formate, acetate, chloroacetate and propionate, arsenic compounds can choose methyl arsine acid, phenyl arsine acid and dimethyl arsine acid, hydrazine can choose acetonitrile and propionitrile. Excerpted from Hydrazine Hydrate Technology and Market Research Report and Hydrazine Hydrate Investment Analysis Report of 6chem.com
Each of the above four methods has its advantages and disadvantages.
Urea method has the advantages of low investment, simple equipment, and is the most economical method for small-scale production (< 1000T /a).
Almost all hydrazine hydrate enterprises in China adopt this method, which has realized continuous production, and the technology is the most mature and easy to master. The synthesis yield is higher than lasie method (>72%), but the raw material price is higher than other methods, so in large-scale production, it can not compete with other methods, and the foreign method has been basically eliminated.
Lassi method has low raw material cost, but high equipment investment and energy consumption, when production scale is large; Its total cost is lower than urea method.
The synthesis yield of hydrazine is close to the theoretical value, and the energy consumption is about 1/3 of that of lasie method, which is only 60%-80%. In the ketoazo process, hydrazine is removed from the top of the tower as a ketoazo azeotrope with water, leaving the rest of the water and salt in the reactor. The azeotrope with high boiling point is stored at the bottom of the tower. A large amount of water needs to be steamed out. And in order to prevent salt precipitation tower kettle, but also in advance evaporation and salt removal, so the energy consumption is large.
Under the situation of energy shortage and price increase, the energy-saving advantages of ketone - nitrogen method are particularly important.
In addition, the equipment investment of ketorenazine method is lower than that of lacey method.
The disadvantage of the ketorenazine process is that it processes organic by-products and consumes acetone. But in general, ketolian-nitrogen method is better than lassi method, so in recent years, the rapid development.
The economic comparison between hydrogen peroxide method, lasci method and ketone nitride method mainly depends on the relative prices of chlorine and NaOH. The yield of this method is 75%, which is attractive when a cheap source of H2O2 is available.
This method uses methyl ethyl ketone, which is more expensive than acetone, but the resulting methyl ketone nitrogen is insoluble in water, easy to separate, and does not need to be rectified, so the energy consumption is lower than that of the ketone nitrogen method.
The advantages of hydrogen peroxide method are: no salt by-products, no environmental pollution, less excess ammonia, phase separation operation for continuous nitrogen recovery, lower energy consumption than other methods, and improved product grade.
Another important advantage of this method is that chlorine is replaced by H2O2, thus avoiding a series of problems such as corrosion and pollution caused by chlorine and NaCl.
Due to the availability of hydrogen peroxide raw material, hydrogen peroxide method has become increasingly mature in recent years and is the most advanced industrial production method at present.
Air oxidation method is one of the most advanced hydrazine preparation methods at present, its raw materials are more reasonable, the basic raw materials are only ammonia and air, other raw materials such as benzophenone, cuprous chloride can be recycled in the synthesis process, and are easy to obtain chemicals. But the method has not yet been commercialized.