Credit process

Diagram of the Haber-Bosch process.

In chemistry, the Haber process or Haber-Bosch process is the reaction of nitrogen and hydrogen gases to produce ammonia. The importance of the reaction lies in the difficulty of producing ammonia at an industrial level.

Around 78.1% of the air around us is molecular nitrogen, N₂. The element as a gaseous diatomic molecule is very stable and relatively inert due to the triple bond that holds the two atoms tightly together. It was not until the early years of the 20th century when this process was developed to obtain nitrogen from air and produce ammonia, that when oxidize forms nitrites and nitrates. These are essential in nitric acid (HNO₃) and fertilizers (example: ammonium nitrate (NH₄NO₃))).

As the natural reaction is very slow, it is accelerated with an iron catalyst (Fe³⁺) and aluminum oxides (Al₂O₃) and potassium (K₂O) allowing equilibrium to be reached more quickly. The factors that increase the yield, by shifting the equilibrium of the reaction towards the products (Le Châtelier's Principle), are conditions of high pressure (150-300 atmospheres) and high temperatures (200-300 °C), resulting in a yield of 10-20%.

ΔH represents the change in energy, also called enthalpy, and is equal to -92.4 kJ/mol. Being negative, it releases heat, so the reaction is exothermic.

History

In 1910, Carl Bosch commercialized the process and secured even more patents. Haber and Bosch were awarded the Nobel Prize in Chemistry in 1918 and 1931 respectively, for their work and developments in the application of technology at high pressures and temperatures. Ammonia was produced using the Haber process (at an industrial level) during the First World War for the manufacture of nitrates and obtaining explosives from it. In this way, Germany was able to do without nitrate from Chile, whose supply was blocked by the British.

Economic and environmental aspects

The Haber process produces more than 100 million tons of nitrogen fertilizer per year. 8.27% of the total world energy consumption in a year goes to this process. The fertilizers that are obtained are responsible for the sustenance of more than a third of the world's population due to the fact that the extraction of nutrients from the soil by agriculture and livestock is large and therefore they must be replenished artificially, although the evil The use of fertilizers produce numerous environmental problems due to erosion and the runoff of nutrients to groundwater and bodies of water, the most emblematic being eutrophication.

Environmental impact

Only 17% of the ammonia used as fertilizer is consumed by humans through food. The rest end up on the ground or in the air. Emissions in the absence of human interference are 0.5 kg per hectare per year. Modern agriculture has multiplied this figure by 20, which has caused the alteration of the natural nitrogen cycle, although its global impact is still not well known.

There are two problems directly related to ammonia. One is the eutrophication of the waters. Nitrates end up in seas and rivers, algae and bacteria with excess nutrients end up with the oxygen that other species need. On the other hand, reactive nitrogen is altering the atmospheric balance, enriching ozone in the troposphere and reducing ozone in the stratosphere. Of course, ammonia has the positive effect of capturing CO₂ in jungles and forests due to the greater presence of nitrogen in the air.