There are four main industrial production methods of hydrazine hydrate: Lasch method, urea method, ketone method and hydrogen peroxide method.

1. Urea oxidation

10% sodium hypochlorite solution and 30% liquid alkali are mixed, then cooled, the mixture is adjusted, and then cooled, the weight ratio of chlorine and alkali in the mixture is adjusted to 1:1.8, and it is put into the reaction tank. Then add an appropriate amount of potassium permanganate, add the urea solution into the reaction tank with stirring, and heat it to about 103-104°C until the raw material liquid boils. The weight ratio of available chlorine is 76:75. The crude hydrazine water of the oxidation product is added to the evaporator for vacuum distillation, and then hydrazine gas and water vapor are introduced into the receiving kettle through a blind blower for initial concentration. The light hydrazine water obtained from the receiving tank is sent to the sieve tower for vacuum concentration, so that the content of hydrazine hydrate reaches the specified value. When the content of sodium hypochlorite exceeds 40%, urea 770, sodium hypochlorite 890030% and liquid alkali 52002. Firstly, sodium hypochlorite was ammoniated with chlorine and caustic soda, and then synthesized at a pressure and temperature of 3.922×107pa. 130-150°C. A hydrazine hydrate reaction solution was obtained. Excess ammonia is removed by steam stripping, and then the product hydrazine hydrate is obtained by evaporation desalination and distillation.

2 Ketone azide method

The ketone azide process is a new technology developed abroad in the 1970s. In this method, ammonia is oxidized with chlorine or sodium hypochlorite in the presence of excess acetone to form methyl ketone diazonium salt, which is then hydrolyzed under pressure to obtain hydrazine. This method has the advantages of high yield, about 95% and low energy consumption. The disadvantage is that due to the addition of acetone, there are organic by-products in the system, which need to be removed and the acetone vapor needs to be processed.

3. Hydrogen peroxide method

This method has been successfully developed by the French chemical company juena coulman. In 1979, a 5,000-ton (100%) hydrazine hydrate plant was built. In this method, ammonia interacts with concentrated H2O2 in the presence of methyl ethyl ketone, acetamide and disodium hydrogen phosphate to form methyl ethyl ketone and water, which are then hydrolyzed under pressure to obtain hydrazine hydrate. Based on H 2 O 2, the yield of hydrazine is about 75%. The method has no by-product sodium chloride, which is beneficial to simplifying the process and environmental protection. The product is easy to dissolve and separate without distillation. But the chemical loss of methyl ethyl ketone is higher than that of acetone.