“At the dawn of the twentieth century, humanity was facing global disaster. Mass starvation, long predicted for the fast-growing population, was about to become a reality. A call went out to the world’s scientists to find a solution.” — Thomas Hager, The Alchemy of Air
The German language has a term called “Bros aus Luft” which means “bread from air”, and it would refer to a famous chemistry process named the Haber-Bosch process, which according to Tim Harford at BBC, half the world wouldn’t be alive without. The Haber-Bosch process is a chemical process that turns air into ammonia, the basis of fertilizer. In chemistry, this process is called nitrogen fixation, a process that converts atmospheric nitrogen into ammonia.
Well, the exact specific process turns atmospheric nitrogen, with hydrogen as a catalyst, to ammonia. To get as much ammonia as possible under equilibrium, however, you need a lot of pressure (about 200 atmospheres) and a lot of heat (about 400–450°C).
For most chemists, conditions like these were not very safe — the famous Henry Le Chatelier, the founder of the stoichiometric principle that tortures young chemistry students, had a terrible explosion in his lab when trying to combine hydrogen and nitrogen under 200 atmospheres and 600°C, almost killing an assistant.
That left an open field for chemists to try to make a new approach for nitrogen fixation. German chemist Fritz Haber would make the discovery.
How did Haber do it?
In the early 1900s, Haber developed a rivalry with a fellow chemist Walter Nernst and made nitrogen fixation his first priority. Soon, based on some of the results published by Nernst as well as his own knowledge of high-pressure chemistry, he developed a new ammonia production system:
What was required was a high pressure, one or more catalysts to accelerate the synthesis of ammonia, high temperature to obtain efficiency, and the separation of ammonia from other molecules and recycling of heat.
From the accident of Le Chatalier and other high-pressure accidents, Haber needed to experiment with equipment that could make the experiment successful. He experimented with a variety of catalysts, including osmium and uranium, as well as iron, nickel, and calcium.
However, Haber soon realized that since the reaction released heat (exothermically), he could recycle the heat the system produced as well. In 1909, he showed that the process could make enough ammonia to consider industrialization.
The industrialization of Haber’s process
German chemical company, BASF, decided to take out a patent on Haber’s process. Some researchers at the company thought that investing in the process would be a waste of time because no industrial device, at the time, could withstand such a high pressure and temperature for a long period of time for the reaction to be both safe and efficient. Osmium could also disappear very quickly.
However, more powerful researchers convinced BASF President, Heinrich Von Brunck, to talk to Haber. He and several others went to Haber’s lab to tell if the company should engage in industrializing the process, and when learning of the pressure required, Brunck asked another chemist at BASF, Carl Bosch. Bosch, who had expertise working on nitrogen fixation, told Von Brunck:
“I think it can work. I know exactly what the steel industry can do. We should risk it.”
With the help of Haber and Bosch, as well as many other researchers, the Haber process started to become industrialized. In 1910, Bosch succeeded to scale the Haber process to industrial-level production, and then ammonia first started to be manufactured at the Oppau plant in Germany in 1913. In five hours, it would turn a ton of liquid ammonia in five hours, making 20 tons of nitrogen per day.
Ammonia is a chemical that can make fertilizer in the form of ammonium nitrate. However, ammonium nitrate can also be used as an explosive, especially when mixed with fuel oil. During Haber and Bosch’s time, there was a world war going on in 1914 and the Oppau plant quickly transitioned from making fertilizer to Chilean nitrate to produce explosives for trench warfare. Bosch would make a new plant after being fearful of French bombers blowing up the Oppau plant.
Haber would move onto even more chemical warfare in the time of World War I. According to Dietrich Stoltzenberg, a chemistry historian, Haber would help lead teams that developed chlorine gas for trench warfare, as well as gas masks that could protect against chemical weapons.
Even after the war, Haber would still be involved in developing chemical weapons, despite being vilified for his role in making chemical weapons. Personally, however, in the early 1930s, Haber, as a Jew, became very worried about the rise of the Nazi party in Germany, particularly the targeting of Jewish scientists. Despite his services to the state as a scientist and his conversion to Christianity, Haber was vilified by other powerful scientists and ordered to dismiss his German personnel.
His family would move to the United Kingdom in 1933, and his kids would become British citizens. He would die the next year of a heart attack.
Bosch, after the Haber-Bosch process, would work on producing synthetic fuel. He started a new company named IG Farben and was the first head of the company. Bosch too was not happy with Hitler’s rise and Nazi policies. After Hitler became chancellor, he was relieved of all his positions of power. He would fall into depression and alcoholism and die in 1940 in Heidelberg.
“But their epochal triumph came at a price we are still paying. The Haber-Bosch process was also used to make the gunpowder and explosives that killed millions during the two world wars. Both men were vilified during their lives; both, disillusioned and disgraced, died tragically.” — Thomas Hager, The Alchemy of Air
Hager and Bosch’s scientific genius made a solution to prevent mass starvation, one they’re often not given credit for. At the same time, their contributions led to the creation of chemical weapons and more explosives that killed countless people in the most deadly wars in human history.
Their legacies are both nuanced and complicated, but the only thing that is certain is that they deserve more attention and recognition for their contributions to humanity.