Catalyst can efficiently reduce NOₓ across a wide temperature range

Nitrogen oxides (NO_x), a major contributor to air pollution, are emitted from a variety of fuel combustion sources—including industrial smokestacks, vehicles, and ships. The emission temperatures of NO_x vary significantly depending on the type of fuel used and operating conditions of the equipment. In light of these changes, researchers have developed a catalyst capable of consistently and efficiently removing NO_x across a wide temperature spectrum.

Led by Professor Seungho Cho from the Department of Materials Science and Engineering at UNIST, in collaboration with Dr. Hong-Dae Kim at the Korea Institute of Industrial Technology (KITECH), the research team developed a novel denitrification catalyst effective between 240°C and 400°C.

This innovation promises to significantly improve the stability and efficiency of NO_x reduction in diverse real-world environments. The study is published in the journal Applied Catalysis B: Environment and Energy.

NO_x released into the atmosphere are known to contribute to severe environmental issues, including fine dust formation, ozone pollution, and acid rain. While Selective Catalytic Reduction (SCR) systems are widely used to convert NO_x into harmless nitrogen (N₂), conventional vanadium-tungsten catalysts typically operate optimally only around 350°C. This narrow temperature window often results in performance degradation under fluctuating field conditions, limiting their effectiveness.

In contrast, the new catalyst demonstrates an impressive 93.6% removal efficiency at 240°C and maintains more than 97% conversion efficiency at higher temperatures. Compared to existing commercial SCR catalysts, which achieve approximately 62.4% efficiency at 240°C, this advancement represents a substantial leap forward.

In addition, the catalyst converts more than 97% of NO_x into nitrogen, with minimal formation of byproducts such as nitrous oxide (N₂O), a potent greenhouse gas. The catalyst also exhibits enhanced longevity, promising more durable and cost-effective operation.

The exceptional performance of this catalyst is primarily attributed to the strategic incorporation of a small amount of hexagonal boron nitride (h-BN). This material plays a crucial role in maintaining vanadium ions in an active state and protecting the catalyst surface from fouling by contaminants such as sulfates and moisture—factors that typically shorten catalyst lifespan.

To facilitate industrial application, the research team also validated the performance of the catalyst in a monolithic form. While powdered catalysts offer superior reactivity, their practical use is often hindered by issues such as dust generation and pressure loss. The monolith structure developed by the team effectively handles high gas flow conditions—processing several tens of micrograms of NO per second at 20 L/min—making it suitable for real-world deployment.

Professor Cho remarked, “The broad operational temperature range of our catalyst enables stable and efficient removal of NO_x from various emission sources, including factories, vehicles, and ships. We anticipate that reducing the reliance on toxic and expensive vanadium will enhance both safety and economic viability in industrial settings.”