Material Science

Sustainable fertilizer manufacturing

Researchers devise a new method which is more environmentally friendly and more competitive

August 18, 2021
The Scitech

An international research team that includes scientists and engineers from The University of Texas at Austin has devised a new method for making urea that is environmentally friendly. “Around the world we need to lower emissions. That’s why we want to develop these more sustainable pathways to produce urea using electrocatalysis instead of this energy-intensive two-step process,” said Guihua Yu, an associate professor of materials science in the Cockrell School of Engineering’s Walker Department of Mechanical Engineering who co-lead the team that published a new milestone paper about the process in Nature Sustainability.

Today, synthetic urea is produced primarily via the Haber-Bosch method. It combines nitrogen and hydrogen to make ammonia, which then bonds with carbon dioxide to make urea. This two-step process requires heating to 400- or 500-degrees Fahrenheit to perform the reaction, using huge amounts of energy and producing significant emissions along the way. Producing urea through electrocatalysis is an alternative process that is more sustainable and energy efficient. However, this method historically has not produced enough to make it viable. It created too many by-products and required much energy to break the bonds of the molecular building blocks to trigger the reaction. Finding the right elements or catalysts to create an efficient chemical reaction was the primary challenge. The UT team used nitrate, instead of the typical nitrogen, to bond with carbon dioxide. And the catalyst solution is composed of indium hydroxide nanomaterials. This highly efficient nanomaterial electrocatalyst has “high selectivity,” Yu said, meaning it produces only what the researchers want it to produce, not a bunch of by-products. And it creates a higher yield of urea than previous attempts using electrocatalysis. “It takes much less energy to break the bonds of nitrate, compared to nitrogen, and that helps produce a lot higher yield of urea,” Yu said.

Yu sees this formula as applicable to large- and small-scale uses. Electrocatalytic devices could be operated by individuals and sold to individual farms so they could generate their own urea for soil. And the hope is to provide alternative solutions to large-scale industrial processes to reduce energy use, which can play a role in a more sustainable future as the population and demand for urea will surely grow.

(Source: The University of Texas at Austin news release)