December 2, 2022
  • December 2, 2022

Sustainable and energy efficient process for urea synthesis

By on July 15, 2021 0


Urea, a vital building block, is found in everything from skin care products to fertilizers. Urea is a natural product of human urine; However, the mass production of urea is a huge undertaking and accounts for around 2% of global emissions and the energy used.

The electrocatalytic reaction between these building blocks could make urea production much more energy efficient. Image credit: University of Texas at Austin.

For decades, engineers and scientists have sought to make urea production more energy efficient, as the demand for fertilizer is huge with the growing population. A team of international researchers including engineers and scientists from the University of Texas at Austin has developed a new technique for producing urea that is more environmentally friendly than the process used so far.

They also focused on making the technology competitive enough to keep pace with existing energy-intensive industrial processes.

The process currently in use involves a two-step thermal process requiring greater amounts of pressure and heat in controlled and harsh environments. The newly designed method has only one step and is based on the concept known as electrocatalysis, which involves using electricity, along with sunlight, to activate chemical reactions in a solution at room temperature. under ambient conditions.

All over the world, we need to reduce emissions. That’s why we want to develop these more sustainable ways to produce urea using electrocatalysis instead of this energy-intensive two-step process..

Guihua Yu, Associate Professor, Materials Science, Walker Department of Mechanical Engineering, Cockrell School of Engineering

Yu co-led the team, and their research results have been published in the journal Sustainability of nature.

Currently, synthetic urea is mainly synthesized using the Haber-Bosch method, one of the 20’s most popular inventions.e century because it facilitated the bulk production of fertilizers and contributed to an increase in the food supply in the world.

The conventional method combines hydrogen and nitrogen to produce ammonia, which binds to CO2 to form urea. This two-step process involves heating up to 400 or 500 ° F for the reaction to occur, while absorbing large amounts of energy and giving off emissions.

The production of urea by electrocatalysis is a more sustainable alternative process that saves energy. However, this method has not been used enough to make it a viable alternative.

In addition, the process produced many by-products and required more energy to break down the bonds of the molecular building blocks in order to activate the reaction.

The initial challenge the researchers faced was to identify the right elements or catalysts to produce an effective chemical reaction. Researchers used nitrate rather than typical nitrogen to bind to CO2. The catalyst solution included indium hydroxide nanomaterials.

According to Yu, the extremely efficient electrocatalyst has “high selectivity,” which means it only creates what scientists intend to create and not a bunch of byproducts. It produced more urea yields compared to previous attempts with electrocatalysis.

It takes much less energy to break the bonds of nitrate, compared to nitrogen, and this helps produce a much higher yield of urea.

Guihua Yu, Associate Professor, Materials Science, Walker Department of Mechanical Engineering, Cockrell School of Engineering

Yu considers that this formula could be applied to both small and large-scale applications. Electrocatalytic devices can be operated by individuals and sold to individual farms so that they can produce urea themselves. The researchers want to provide large-scale industrial processes with an alternative solution to reduce energy consumption, which is crucial for a sustainable future as the population and the demand for urea will increase in the years to come.

The other stages of this study involve improving selectivity and yield, as well as a prototype device that improves production. Researchers are looking for ways to power the process with solar energy instead of direct electricity.

The study is funded by grants from the US Department of Energy and the Welch Foundation. The team included scientists from Nanyang Technological University in Singapore, China University of Science and Technology, and Harbin Institute of Technology.

Journal reference:

Lv, C., et al. (2021) Selective electrocatalytic synthesis of urea with nitrate and carbon dioxide. Sustainability of nature.