Ammonia production in laboratory and industrial scale

Ammonia (NH3) is a chemical compound of hydrogen with nitrogen. He got his name from the Greek word "hals ammniakos" or Latin "sal ammoniacus", which are translated lonely - "ammonia". It is this substance called ammonium chloride that was obtained in the Libyan desert in the oasis of Ammonium.

Ammonia is considered a very toxic substance that can irritate the mucous membranes of the eyes and respiratory tract. Primary symptoms of ammonia poisoning are abundant lacrimation, dyspnea and pneumonia. But at the same time, ammonia is a valuable chemical substance that is widely used for the production of inorganic acids, for example, nitric, cyanide, and urea and nitrogen-containing salts. Liquid ammonia is an excellent working substance of refrigerated containers and machines, since it has a high specific heat of evaporation. Aqueous solutions of ammonia are used as liquid fertilizers, as well as for the ammonization of superphosphates and fat mixtures.

Obtaining ammonia from exhaust gases in the process of coal coking is the oldest and most accessible method, but to date it has become obsolete and is practically not used.

The modern and basic way is to obtain ammonia in industry based on the Haber process. Its essence in the direct interaction of nitrogen and hydrogen, which occurs as a result of the conversion of hydrocarbon gases. As a raw material, natural gas, refinery gases , associated petroleum gases, residual gases from the production of acetylene are usually used. The essence of the method of conversion production of ammonia is decomposition of methane and its homologues at high temperature into components: hydrogen and carbon monoxide with the participation of oxidizing agents - oxygen and water vapor. At the same time, oxygen-enriched air or atmospheric air is mixed with the converted gas. Initially, the reaction for the production of ammonia based on the convertible gas proceeds with the release of heat, but with a decrease in the volume of the reaction starting materials:

N2 + 3H2 ↔ 2NH3 + 45.9 kJ

However, the production of ammonia on an industrial scale is carried out using a catalyst and under artificially created conditions that increase the yield of the finished product. In the atmosphere where ammonia is being produced, the pressure increases to 350 atmospheres, and the temperature rises to 500 degrees Celsius. Under such conditions, the yield of ammonia is about 30%. The gas is removed from the reaction zone by the cooling method, and nitrogen and hydrogen that have not reacted return to the synthesis column and can again participate in the reactions. During the synthesis it is very important to purify the mixture of gases from catalytic poisons, substances that can negate the effect of catalysts. Such substances are water vapor, CO, As, P, Se, O2, S.

Porous iron with impurities of aluminum and potassium oxides acts as a catalyst in the reactions of nitrogen and hydrogen synthesis. Only this substance, from all the 20,000 previously tried, allows to reach the equilibrium state of the reaction. This principle of obtaining ammonia is considered the most economical.

The production of ammonia in the laboratory is based on the technology of displacement of it from ammonium salts by strong alkalis. Schematically, this reaction is as follows:

2NH4CI + Ca (OH) 2 = 2NH3 ↑ + CaCl2 + 2H2O

or

NH4Cl + NaOH = NH3 ↑ + NaCl + H2O

To remove excess moisture and to drain ammonia, it is passed through a mixture of caustic soda and lime. The production of ammonia is very dry, as a result of the dissolution of metallic sodium in it and subsequent distillation of the mixture. Most often, such reactions are carried out in a closed metal system under vacuum. Moreover, such a system must withstand high pressure, which is achieved by emitting ammonia vapor, up to 10 atmospheres at room temperature.