A method has been developed to synthesize high-performance ammonia (NH3) with catalytic performance 30% higher than existing methods at low temperatures and low pressures, raising expectations that ammonia will be produced in local areas in the future.

A research team led by Professor Baek Jong-beom of the Department of Energy and Chemical Engineering at UNIST (President Yong-Hoon Lee) has developed a mechanochemical method for improving ammonia yield using a potassium reaction promoter.

Ammonia (NH3), a chemical compound synthesized from nitrogen and hydrogen through a chemical reaction, is widely used in fertilizers and the chemical industry and is gaining attention as a hydrogen carrier. Ammonia has a hydrogen storage density per unit volume 1.7 times higher than that of liquid hydrogen, allowing it to store large amounts of hydrogen. Furthermore, it liquefies easily at natural temperatures and pressures, making it easy to transport and distribute.

First, to synthesize ammonia, the triple-layer nitrogen gas bond must be broken. Since the early 1900s, ammonia has been mass-produced using the Haber-Bosch process, which involves reacting nitrogen and hydrogen under high temperature and pressure conditions using a catalyst. In particular, potassium oxide, which promotes the activity of iron catalysts in the Haber-Bosch process, plays a role in stabilizing potassium at high temperatures. However, potassium oxide contains oxygen, which hinders the breakdown of nitrogen bonds, thus lowering the performance of the iron catalyst.

To improve this, the research team devised a method for synthesizing ammonia at low temperature and pressure using mechanochemical methods. By using potassium as a direct reaction promoter instead of potassium oxide, they were able to effectively break nitrogen bonds. With this method, the research team achieved catalytic performance approximately 30% higher than that of potassium oxide and an ammonia yield (94.5%) approximately 12% higher than that of an iron catalyst alone (82.5%). Furthermore, ammonia was synthesized under milling conditions 3.5 times lower (100 rpm) than the milling speed (350 rpm) when using only an iron catalyst.

Professor Baek Jong-beom of the Department of Energy and Chemical Engineering said, “We have developed a method to produce ammonia more efficiently at low temperatures and pressures using a reaction promoter,” adding, “This will enable decentralization of ammonia production, allowing ammonia to be produced even in local areas.”

This study, which presents a new technology that can increase the energy efficiency of ammonia synthesis and accelerate the commercialization of mechanochemical methods, was published in the international academic journal 'Nature Communications' on April 22.