Atomization of a three-phase mixture of water, nitrogen gas, and a solid catalyst in a low-tech, horticultural gas-powered atomizer yields ammonia at low energy and low cost.
Researchers at Stanford University have discovered a simple and environmentally friendly way to make ammonia from nitrogen and tiny water droplets in the air.
Ammonia (NH3) is the starting point for making chemical fertilizers for crops. For over a century, the world has relied on the Haber-Bosch process to produce large amounts of ammonia. This breakthrough technology revolutionized agriculture and helped feed a burgeoning population. However, industrial processes are energy intensive. To break the strong nitrogen bonds, the Haber-Bosch process requires pressures of approximately 80-300 atmospheres and temperatures of 572-1000 F (300-500 C). The steaming of natural gas involved in this process also releases large amounts of carbon dioxide that contributes to climate change.
Overall, to meet the current global annual demand for 150 million tons of ammonia, the Haber-Bosch process consumes more than 2% of the world’s energy and about 1% of the carbon dioxide emitted into the atmosphere. occupies
In contrast, the innovative method debuted by Stanford researchers does not require a less specialized environment.
“We were shocked to learn that with just air and water, and using something as basic as an atomizer, ammonia can be produced in an environment of mild everyday temperature and pressure.”Science and Stanford Chemistry professor at the Graduate School of Humanities. “If we can scale up this process, it will be a new, environmentally friendly way to produce ammonia, one of the most important chemical processes in the world.”
The new method also has the potential to sustainably produce valuable chemicals because it uses little energy and is low cost. Xiaowei Song, a postdoctoral researcher in chemistry at Stanford University, is the lead author of the study, which was published April 10 in his Proceedings of the National Academy of Sciences.
New chemistry from blue sky research
The new chemistry discovered follows in the footsteps of recent pioneering work by Zalle’s lab, which probed the surprisingly high reactivity of long-overlooked microdroplets of water. In a 2019 study, Zare and his colleagues newly demonstrated the spontaneous formation of caustic hydrogen peroxide in microdroplets in contact with surfaces. Subsequent experiments revealed the mechanism by which charge jumps between liquids and solids, creating molecular fragments known as reactive oxygen species.
Furthering these findings, Song and Zare began a collaboration with study co-author Basheer Chanbasha. Basheer Chanbasha is Professor of Chemistry at King Fahd University of Petroleum and Minerals in Saudi Arabia. Chanbasha, who specializes in nanomaterials for energy, petrochemical, and environmental applications, came to Stanford University as a visiting fellow last summer.
The research team focused on catalysts (a term for substances that speed up a chemical reaction but are not themselves decomposed or changed by the reaction) and thought they could help burn a chemical pathway to ammonia. . The catalyst consists of an iron oxide called magnetite and a synthetic membrane made up of repeating chains of two large molecules invented by him in the 1960s.
The researchers applied the catalyst to a graphite mesh that Song incorporated into a gas-powered atomizer. The atomizer ejected microdroplets in which pumped water (H2O) and compressed nitrogen molecules (N2) reacted in the presence of a catalyst. Using a device called a mass spectrometer, Song analyzed the properties of the microdroplets and saw traces of ammonia in the collected data.
Low-tech, low-energy synthesis of ammonia
Zare and colleagues are very happy with the results, especially considering the relatively low-tech approach. “With our method, we don’t need to apply voltage or radiation,” he said.
From a broader chemistry perspective, this method is notable for using three phases of matter. Nitrogen as gas, water as liquid, and catalyst as solid. “To our knowledge, the idea of using gases, liquids and solids all at the same time to trigger chemical transformations is the first of its kind and has great potential to advance other chemical transformations. ” he said Zare.
Zare, Song, and Tambasha’s methods of producing ammonia are promising, but are currently only in the demonstration stage. The researchers plan to investigate ways to concentrate the ammonia produced and evaluate ways to scale the process to commercially viable levels. Haber-Bosch is efficient only in large-scale facilities, but the new ammonia production method is portable and can be done on-site or even on-demand at the farm. Reduces greenhouse gas emissions associated with transportation.
“Further development will help our method of ammonia production address two major looming problems: mitigating climate change while continuing to feed billions of people on the planet. “We are hopeful and excited to continue this line of research.”
Original: New method to produce ammonia could stave off global energy use
Than: Stanford University
