Views:2 Author:Site Editor Publish Time: 2021-08-20 Origin:Site
The main industrial production methods of hydrazine hydrate are laxi method, urea method, ketone nitrogen method and hydrogen peroxide method. The urea process is mainly used in China.
Mix 10% sodium hypochlorite solution with 30% liquid alkali, then cool, adjust the mixture, then cool, adjust the weight ratio of chlorine to alkali in the mixture to 1:1.8, and place in the reaction pot. Add an appropriate amount of potassium permanganate, stir the urea solution into the reaction pot, heat to about 103-104℃ until the material boils. The amount of urea is calculated according to the effective chlorine, and the weight ratio of effective chlorine is 76:75. The above oxidized product, crude hydrazine water, was added to the evaporator for vacuum distillation. Hydrazine gas and water gas were imported into the receiving kettle through a blind air blower for initial enrichment. The light hydrazine water obtained from the receiving kettle is sent to the sieve tray column for vacuum enrichment, so that the hydrazine hydrate content reaches the specified value. When the content ≥40% urea 770 sodium hypochlorite 890030% liquid alkali 52002. Sodium hypochlorite ammoniation method is firstly prepared by chlorine gas and caustic soda, and then synthesized at 3.922×107Pa pressure and 130-150℃ to obtain hydrazine hydrate reaction liquid. The excess ammonia is removed by gas extraction, and then the finished hydrazine hydrate is obtained by evaporation desalination and rectification.
Ketone nitriding method is a new technology developed in 1970s abroad. In this method, ammonia is oxidized with chlorine or sodium hypochlorite in the presence of excessive acetone to produce ketone and nitrogen, and then hydrolysed under pressure to obtain hydrazine. The advantages of this method are high yield, up to about 95%, and low energy consumption. The disadvantage is that the addition of acetone, so that there are organic by-products in the system, need to be removed, and acetone steam needs to be treated.
The method was developed by the French chemical company Yuchena-Kuhlmann. Built in 1979 with an annual output of 5000 tons (100%) hydrazine in water. In this method, ammonia and concentrated H2O2 interact with each other in the presence of methyl ethyl ketone, acetamide and disodium hydrogen phosphate to produce methyl ethyl ketone with nitrogen and water, and then hydrolysate under pressure to obtain hydrazine hydrate. The yield of hydrazine is about 75% in terms of H2O2. This method has no by-product sodium chloride, which is beneficial to simplify the process and environmental protection, and the product is easy to dissolve and separate without distillation. However, the loss of methyl ethyl ketone is higher than that of acetone in the methyl ketone nitrogenization process.