Looking through the records of the Nobel Prize in Chemistry, you can see that there was no award from 1916 to 1917, because during this period, Europe was experiencing the First World War. The prize was awarded in 1918, and the Chemistry Prize was awarded to Germany. Chemist Haber. This aroused discussion among scientists. Some scientists from Britain, France and other countries publicly expressed their opposition. They believed that Hubble was not qualified to receive this honor. Why is this?
With the development of agriculture, the demand for nitrogen fertilizer is growing rapidly. Before the 19th century, the source of nitrogen fertilizer needed in agriculture mainly came from organic by-products, such as manure, seed cake and green manure. A large sodium nitrate deposit was discovered in Chile in 1809 and was quickly exploited. On the one hand, this mineral resource is limited, and on the other hand, the military industry also requires a large amount of saltpeter to produce explosives. Therefore, another way must be found to solve the source of nitrogen fertilizer.
Some far-sighted chemists pointed out: Considering the future food problem, in order to save future generations from hunger, we must hope that scientists can achieve atmospheric nitrogen fixation. Therefore, fixing the abundant nitrogen in the air and converting it into a usable form became a major issue that attracted the attention and concern of many scientists in the early 20th century. Haber is one of the chemists engaged in experimental and theoretical research on the process conditions of ammonia synthesis.
The industrial production of ammonia using nitrogen and hydrogen as raw materials was once a difficult subject. It took about 150 years from the first laboratory development to industrial production. In 1795, someone tried to synthesize ammonia at normal pressure, and later someone tried it at 50 atmospheres, but they all failed. In the second half of the 19th century, great progress in physical chemistry made people realize that the reaction of synthesizing ammonia from nitrogen and hydrogen is reversible. Increasing pressure will push the reaction in the direction of producing ammonia: increasing temperature will move the reaction in the opposite direction. However, if the temperature is too low, the reaction speed will be too small; the catalyst will have an important impact on the reaction. This actually provides theoretical guidance for ammonia synthesis experiments. At that time, the authority of physical chemistry, Nernst of Germany, clearly pointed out that nitrogen and hydrogen can synthesize ammonia under high pressure conditions, and provided some experimental data. The French chemist Le Chatery was the first to try to conduct an experiment to synthesize ammonia under high pressure, but he gave up this dangerous experiment because oxygen was mixed into the nitrogen-hydrogen mixture, causing an explosion. Haber, who had a good foundation in physical and chemical research, was determined to overcome this daunting problem.
Haber first conducted a series of experiments to explore the optimal physical and chemical conditions for ammonia synthesis. Some of the data he obtained in the experiment were different from Nernst's. He did not blindly follow authority, but relied on experiments to test, and finally confirmed that Nernst's calculations were wrong. With the assistance of a student from the United Kingdom, Rosenau, Haber successfully designed a set of equipment suitable for high-pressure experiments and a process for synthesizing ammonia. This process is: blowing water vapor above the hot coke can obtain almost A mixture of equal volumes of carbon monoxide and hydrogen. The carbon monoxide further reacts with water vapor under the action of a catalyst to obtain carbon dioxide and hydrogen. Then the mixed gas is dissolved in water under a certain pressure, and the carbon dioxide is absorbed, thus producing purer hydrogen. Similarly, water vapor is mixed with an appropriate amount of air and passed through red-hot carbon. The oxygen and carbon in the air generate carbon monoxide and carbon dioxide, which are absorbed and removed, thereby obtaining the required nitrogen.
The mixed gas of nitrogen and hydrogen synthesizes ammonia under high temperature, high pressure and the action of a catalyst. But what kind of high temperature and pressure conditions are optimal? What kind of catalyst is best? This still requires a lot of effort to explore. With perseverance, after continuous experiments and calculations, Hubble finally achieved inspiring results in 1909. This means that under the conditions of a high temperature of 600C, a pressure of 200 atmospheres, and osmium as a catalyst, synthetic ammonia with a yield of about 8 can be obtained. The conversion rate of 8 is not high, which will of course affect the economic benefits of production. Haber knew that the ammonia synthesis reaction could not achieve as high a conversion rate as sulfuric acid production, where the conversion rate of the sulfur dioxide oxidation reaction was almost 100.
what to do? Haber believes that this process is feasible if the reaction gas can be circulated under high pressure and the ammonia generated by the reaction is continuously separated from this cycle. So he successfully designed the recycling process of raw gas. This is the Haber process for the synthesis of ammonia.
Going out of the laboratory and carrying out industrial production will still require hard work. After Haber patented the process he designed, he handed it over to the Baden Aniline and Soda Ash Manufacturing Company, Germany's largest chemical company at the time. The company originally planned to use the arc method to produce nitrogen oxide and then synthesize ammonia. Comparing the two, the company immediately canceled the original plan and organized engineering and technical personnel headed by chemical expert Bosch to put Haber's design into practice.
First of all, based on Haber's process flow, they found a more reasonable method to produce a large amount of cheap raw materials nitrogen and hydrogen. Through experiments, they realized that although osmium is a very good catalyst, it is difficult to process because it is easily converted into volatile tetraoxide when it comes in contact with air. In addition, the reserves of this rare metal are very small in the world. The second catalyst suggested by Haber was uranium. Not only is uranium expensive, it's also sensitive to trace amounts of oxygen and water. In order to find an efficient and stable catalyst, they conducted as many as 6,500 experiments and tested 2,500 different formulas in two years, and finally selected an iron catalyst containing lead and magnesium promoters. Developing suitable high-voltage equipment is also key to the process. At that time, low carbon steel could withstand 200 atmospheres of pressure, but it was afraid of decarburization and corrosion by hydrogen. Bosch thought of many ways, and finally decided to add a layer of wrought iron to the low-carbon steel reaction tube. Although wrought iron has no strength, it is not afraid of hydrogen corrosion, which finally solved the problem.
Haber's idea of ??ammonia synthesis was finally realized in 1913, and a synthetic ammonia plant with a daily output of 30 tons was built and put into operation. Since then, ammonia synthesis has become a rapidly developing and very active part of the chemical industry. The creation of the synthetic ammonia production method not only opened up a way to obtain fixed nitrogen, but more importantly, the realization of this production process had a significant impact on the development of the entire chemical process. The research on synthetic ammonia comes from correct theoretical guidance, and in turn, the research and testing of synthetic ammonia production technology promotes the development of scientific theories. In view of the realization of the industrial production of synthetic ammonia and the promotion of the development of chemical theory by its research, it was correct to decide to award the Nobel Prize in Chemistry to Haber. Harper's acceptance of this award is well-deserved. Some British and French scientists believe that Haber is not eligible to win the Nobel Prize. Why? Some people once believed that without the establishment of the synthetic ammonia industry, Germany would not have sufficient arms reserves, and the military would not dare to rashly launch World War I. With the synthetic ammonia industry, ammonia can be oxidized into nitrate to ensure the production of gunpowder. Otherwise, gunpowder cannot be guaranteed solely by relying on Chilean saltpeter. Of course, scientists are not directly responsible for certain scientific inventions and creations being used in unjust wars. The criticism of Haber by the British and French scientific circles focused more on Haber's performance in the First World War.
In 1906, Haber became a professor of chemistry at the University of Karlsruhe. In 1911, he was appointed director of the Wilhelm Institute of Physical Chemistry and Electrochemistry near Berlin, and concurrently served as a professor at the University of Berlin. When the world war broke out in 1914, the blind patriotic enthusiasm stirred up by national chauvinism deeply involved Harper in the vortex of the old war. The laboratory he led became an important military institution serving the war: Haber undertook the supply and development of materials needed for the war, especially in the development of war gases. He once mistakenly believed that poison gas attacks were a good way to end the war and shorten the war, so he served as the scientific director of Germany's poison gas warfare during the war.
According to Harbin's suggestion, in January 1915, the German army placed cylinders containing chlorine gas at the front of the position and used wind to blow the chlorine gas toward the enemy positions. The first field trial was a success. On April 22 of that year, during the Battle of Ypres launched by the German army, on a 6-kilometer-wide forward position, the German army released 180 tons of chlorine gas within 5 minutes. The yellow-green poisonous gas, about a person high, rushed along the ground with the force of the phoenix. Towards the British and French positions (chlorine gas has a higher specific gravity than air, so it sinks to the lower level and moves along the ground), enters the trenches and stays there.
This poisonous wave caused the British and French troops to feel pain in their noses and throats, and then some people suffocated to death. The British and French soldiers were so frightened that they panicked and fled in all directions. It is estimated that about 15,000 British and French troops were poisoned. This was the beginning of modern chemical warfare using lethal poisons on a large scale for the first time in military history. Since then, both sides of the war have used poisonous gas, and new types of poisonous gas have been developed. Even the German authorities had not estimated the casualties caused by poison gas. However, the use of poison gas and chemical warfare was unanimously condemned by the people in European countries. Scientists even criticized this inhumane behavior. In view of this, scientists from Britain, France and other countries naturally opposed the award of the Nobel Prize in Chemistry to Haber. Haber was also greatly shaken mentally. Not long after the war ended, he was afraid of being regarded as a war criminal and fled to the countryside for about six months.