How is ammonia formed? How is ammonia formed?

Nitrogen and hydrogen can be synthesized when discharged.

1. Artificial nitrogen fixation H2 and N2 are commonly used in industry to synthesize ammonia under catalysts, high temperatures, and high pressures Recently, two Greek chemists, George Marnellos and Michael Elstoukides of the University of Aristotle in Thessaloniki, have invented a new method for synthesizing ammonia (Science, 2OCT 1998, p98).At atmospheric pressure, hydrogen and nitrogen diluted with helium are respectively passed into an electrolytic cell heated to 570 with strontium-cerium-yttrium-perovskite porous ceramics (SCY) as solid electrolytes, and are converted into ammonia by catalysis of porous palladium polycrystalline films covering the inner and outer surfaces of the solid electrolyte, with a conversion rate of 78. Comparison: The Haber process for nearly a century typically has a conversion rate of 10 to 15!

They used ** gas chromatography to detect the gas entering and leaving the electrolytic cell, and estimated the yield of ammonia by using the pH change caused by HCl absorption, which confirmed that increasing the partial pressure of nitrogen was ineffective in improving the conversion rate; Although increasing the current and temperature increases the transfer speed of protons in SCY, the conductivity of SCY is limited by temperature, and the temperature increase accelerates the decomposition of ammonia. 2. Natural nitrogen fixation Atmospheric nitrogen fixation Lightning can convert nitrogen in the air into nitric oxide, and a lightning can produce 80 1500kg of nitric oxide. It is also a natural nitrogen fixation.

Natural nitrogen fixation is far from meeting the needs of agricultural production. Biological nitrogen fixation Leguminous plants contain rhizobia, which contain nitrogen enzymes that convert nitrogen in the air into ammonia, which in turn is converted into nitrogen compounds. The role of nitrogenase can be briefly described as follows:

In addition to the rhizobia of leguminous plants, there are nitrogen-fixing spirofunctions in the roots of pastures and other grasses, and some prokaryotic lower plants, nitrogen-fixing cyanobacteria, and autogenous nitrogen-fixing bacteria, all contain nitrogenases, which have nitrogen-fixing effects. This category is biological nitrogen fixation that is naturally nitrogen-fixing.

Catalysts also play an extremely important role in nature, but they are called enzymes there. The role of enzymes in the metabolism of substances is to optimize certain chemical reactions, it is selective: a certain type of molecule is selected from a large number of supplies and converted into a certain product, and this excellent chemical reaction can be carried out under very mild conditions.

Most of the artificially manufactured catalysts are not very specific and often require relatively high temperatures or pressures when they work, but despite this, they play a decisive role in maintaining the effectiveness of chemical synthesis and the rationality of production costs, and many chemical reactions can only be carried out smoothly through catalysts.

To give you an example: ammonia (NH3) is synthesized from nitrogen (N2) and hydrogen (H2) in the air, and for decades the world has produced large quantities of ammonia using the Haber-Bosch process, and about 85% of the ammonia is still processed into fertilizer. Chemist Harper developed the synthesis method of ammonia, which was later developed by the entrepreneur Bo Shi and transformed into a large-scale industrial production method, which was adopted by BASF in 1914.

Here, a mixture of nitrogen (in air) and hydrogen (water and natural gas) is heated to a high temperature of about 500 °C and allowed to flow through a catalyst containing trace amounts of potassium, calcium, aluminum, etc. at a pressure of about 20,000 kPa

The detailed function of the catalyst in this reaction was unknown for a long time, and it is only recently that the specialized modern research methods of surface chemistry have revealed the role of the iron chip catalyst, which combines with the nitrogen molecule on its surface and weakens the already very strong link between the two nitrogen atoms, so that the two nitrogen atoms can be separated with less energy consumption, and then the individual nitrogen atoms (also attached to the surface of the catalyst) will quickly react with the hydrogen atom to synthesize ammonia.