Two Tragic Chemists

BY ERSHUANG LU

Imagine being a chemist who manipulates the fundamental molecules of the world to create towering structures of iron and bronze, or biological marvels that can stimulate a dead man’s heartbeat. Imagine inventing a machine that shakes the foundations of agriculture. Imagine publishing it to the world, receiving accolades upon accolades for single-handedly saving millions, billions from starvation. Imagine achieving fame, wealth, and fortune. 

Now imagine dying miserably despite these achievements. 

This is the reality of Fritz Haber and Carl Bosch, inventors of the eponymous Haber-Bosch process, a revolutionary chemical method that mass-produces nitrogen fertilizer. Their work allowed modern agriculture to flourish and even earned them the coveted Nobel Prize for Chemistry, yet both laureates perished miserably at the end of their lives.

Food Crisis

In 1898, William Crookes, the president of the British Academy of Sciences, made a startling prediction: if the current rate of population growth was maintained, the human species would suffer a major starvation point around 1931. Since arable land on Earth was limited, cultivation would cause soil to slowly lose its fertility, meaning mass famine was bound to occur.

At the beginning of the Industrial Revolution, many countries relied on old-fashioned fertilizers like guano, aka bird poop, which supplies nitrogen essential to plant growth. But by the end of the century, buying guano as fertilizer was no longer feasible. The world’s limited supply of guano would be unable to accommodate the growing demand forever. 

As the world population increased, the price of guano became comparable to gold. European and American countries even fought wars over it. One famous example is the Chincha Islands War. Spain tried to regain its lost influence over its former South American colonies by seizing the Chincha Islands, which was rich in guano. Ultimately, Peruvian and Chilean forces successfully defended the island from Spain with help from Britain and the United States.

Ultimately, guano was limited. When Crookes made his prediction, people already knew that it was no longer possible to maintain food production by competing for guano. Since the world did not have enough natural fertilizer to meet the needs of the coming twentieth century, there was only one solution: the creation of thousands of tons of synthetic fertilizer.

Previous attempts 

Nitrogen exists in abundant amounts in the atmosphere as pure gas. Although synthesizing fertilizer seems like it should be as easy as freeing those nitrogen molecules and infusing them into dirt, a little high school chemistry should let you see the problem. Nitrogen has a triple bond that is difficult to break. In fact, there are only two ways to break the triple bond in nature. 

The first method is lightning. Lightning releases huge amounts of energy in a short burst of time, which causes nitrogen molecules to decompose into free radicals that react with oxygen to generate nitrogen dioxide. 

The second method is called biological nitrogen fixation. It relies on microorganisms that convert gaseous nitrogen into ammonia. A famous example of such a microorganism is rhizobia, a diazotrophic bacteria capable of fixing nitrogen after infecting the roots of a legume plant, but this method was too slow to feed the rapidly growing population.

As early as 1811, a German chemist named Georg Hildebrant tried to use high pressure to decompose nitrogen, but he was unsuccessful. In the following century, many scientists followed his example and attempted to use high temperature and pressure to fixate nitrogen. They all failed. 

Even Wilhelm Ostwald, a giant in the chemistry field who’d won the Nobel Prize in 1909 for his contributions to the fields of catalysis and was also the mentor to Fritz Haber’s rival, Walter Nernst, attempted to crack the nitrogen problem. He ran an experiment using high temperature, high pressure, and catalytic steel, and seemed to successfully generate ammonia. When he prepared to submit his patent, it was Carl Bosch who pointed out the fatal flaw in his experiment—the steel used by Ostwald contained ferric nitrate, which reacts with hydrogen to produce ammonia at high temperature and pressure. So the reaction was not between nitrogen and hydrogen at all. Ostwald had failed.

Success

After so many repeated failures, people started to doubt synthesizing ammonia from nitrogen and hydrogen was possible. But Fritz Haber, who had spent five years of his youth on the problem, believed he had found a way.

The overall process—later named the Haber-Bosch process in honor of the two chemists who revolutionized the method—relies on a simple reaction between nitrogen and hydrogen to form ammonia. 

N₂ + 3H₂ → 2NH₃

After using higher pressure and running the experiment for more than 48 hours, Haber managed to get traces of ammonia as the product. He reported his results in the paper and sent it to the academic meeting.

This discovery excited everyone in the industry. Haber’s results showed that ammonia could be synthesized from atmospheric nitrogen at relatively high yields. Fertilizing the soil would no longer rely on limited amounts of guano, but man-made materials. Humanity had taken a step away from world starvation. 

However, publication of revolutionary reactions always draws suspicion and arguments, and Haber’s discovery was no exception. In strolled Haber’s opponent: Walther Nernst, the inventor of the Nernst equation that describes the electrochemical relationship between chemical reduction potential and the activity of a specific species. 

While Haber was still doing research at his university, Nernst was already well-known in the academic field of physical chemistry. When Nernst saw Haber’s report, which described the production of a small amount of ammonia gas, he wrote to Haber, calling his experimental data questionable and claiming that he would correct Haber’s mistakes in the next academic meeting (Nernst’s own theory supported lower ammonia production.)

Haber believed this was an insult and an attack on his academic reputation. So he repeated the experiment, this time using a higher pressure environment than Nernst. The final output was slightly lower than the previous experiment, but still much higher than Nernst’s data. 

Despite this, Nernst remained unconvinced. He claimed that Haber’s data and experiments would be a world-changing discovery—if they were accurate. 

Haber accepted the challenge and readjusted his experiments. In order to defeat Nernst and prove that his methods worked he needed better results. Since commonly-used metals had already been tested and yielded mediocre results, Haber took advantage of his position as a technical consultant in a lightbulb factory to obtain rare metals to use as catalysts, including platinum, uranium, and osmium. After several rounds of experiments, he determined osmium catalysts to have the highest yield.

From lab to factory

Following this monumental discovery, Badische Anilinund Sodafabrik (BASF), a European chemical production company and Haber’s financier, sent Carl Bosch to industrialize Haber’s process. Although Haber’s machines weren’t massive, the need for a suitable plant that could maintain such high pressure and temperature dramatically increased the difficulty of engineering.

One of the biggest problems with the creation of industrial plants was the cracking of reaction chamber walls during the reaction. Over the next few months, Bosch and his team grappled with this dilemma. Every method they tried to stop the cracking failed. 

Finally, Bosch had a bold idea. They’d initially assumed that the inner wall of the reaction vessel should be a single layer in order to withstand the harsh reaction conditions and to prevent the reaction of hydrogen with stainless steel, which would make it brittle and prone to cracking. But what if there were two layers: one layer to protect the steel from being further eroded by hydrogen, and another layer to bear high temperature and high pressure? They put this theory to the test—and it worked! 

Another problem Bosch’s team faced was the metal catalyst. The use of rare metals like platinum, uranium, and osmium was permitted in the laboratory since they were used in small, catalytic amounts. But in industry, the cost would be astronomical. After many attempts with various alloys, a member of the team who was an expert on metal catalysts devised a solution. Small amounts of aluminum oxide mixed with steel could substitute osmium, greatly reducing the cost of ammonia production. 

Revolutionized by Haber and industrialized by Bosch, the production of ammonia for the fertilizer industry took off. Crookes’s foreboding prediction of mass starvation had disappeared. In turn, Haber achieved the success he yearned for: a return to academia and ascendance to becoming a leader of the Kaiser Wilhelm Society for the Advancement of Science (KWI).

The End of Haber

When the First World War began, Haber was one of the acting leaders of KWI. As an absolute patriot, his team and he began experiments to produce chlorine and other toxic gasses. Soon, Germany became the first country to use chemical weapons. At the same time that he saved billions with the Haber-Bosch process, Haber killed millions more with his chemistry. 

Haber may have had ethical considerations, but he reasoned that it was all in the name of ending the war faster. Tragically, his wife Claire, another chemist, was deeply disappointed by Haber’s involvement in the war and chose to shoot herself after hearing about the release of chemical weapons. 

After Germany fell into an economic depression after WWI, Haber desperately tried to find a new way to pay back Germany’s debt. Of course, these attempts were unsuccessful. 

Soon after the Nazis came to power, Haber, a Jewish person, was fired from all his positions, destroying his bottom line and financial support. Though he fled Germany, many countries refused to accept him due to his deeds in WWI, and he soon died of heart failure in the United Kingdom as a British national.

The End of Bosch

Bosch was disgusted by Hitler’s racial discrimination and believed that people’s value was determined by their merit, not by their race or religion. This was the belief that promoted him from the son of a small ordinary factory owner to the technical director of the largest chemical company in the country. He used his own wealth to financially support a newspaper association that opposed Hitler’s party. 

But reality soon settled in, caring little for talents or beliefs. After Bosch publicly disavowed Hitler and repeatedly protested Hitler’s policies, the company BASF fired Bosch in 1937 to cater to the Nazi government. 

Bosch was betrayed. He was a Nobel Prize laureate with lofty ideals, and his synthetic method of producing ammonia had brought unprecedented profits to the company, but they tossed him aside like he was nothing. Like Haber, his physical and mental health collapsed. After years of depression and alcoholism, the Nobel laureate who changed the world died in 1940.

Haber and Bosch were genius chemists whose lives ended tragically. Although they had a tremendous impact on the world we know today and left huge legacies in the chemistry field, their lives show that we are shaped by our history and decisions as much as the world is shaped by us.

References

1. Hager, Thomas. The Alchemy of Air: A Jewish Genius, a Doomed Tycoon, and the Scientific Discovery That Fed the World but Fueled the Rise of Hitler. Broadway Books, 2008. 
2. Smil, Vaclav. Enriching the Earth: Fritz Haber, Carl Bosch, and the Transformation of World Food Production. MIT, 2004.
3. Population by World Region. https://ourworldindata.org/grapher/population-regions-with-projections (accessed 2023-06-29). 
4. Zahran, H. H. Rhizobium-Legume Symbiosis and Nitrogen Fixation under Severe Conditions and in an Arid Climate. Microbiology and Molecular Biology Reviews 1999, 63 (4), 968–989. DOI:10.1128/mmbr.63.4.968-989.1999. 
5. The Haber-Bosch Process : What Is It and Why Is the Process so Important ? https://www.scienceabc.com/pure-sciences/the-haber-bosch-process-what-is-it-why-is-the-process-so-important.html (accessed 2023-06-29). 
6. Modak, J. M. Haber Process for Ammonia Synthesis. Resonance 2002, 7 (9), 69–77. DOI:10.1007/bf02836187.