Breakthrough catalyst turns carbon dioxide into essential ingredient for clean fuels

A research team led by Dr. Kee Young Koo from the Hydrogen Research Department at the Korea Institute of Energy Research (President Yi Chang-Keun, hereafter referred to as KIER) has developed a world-class catalyst for the reverse water–gas shift reaction, transforming carbon dioxide, a major greenhouse gas, into a key building block for eco-friendly fuels.

The reverse water–gas shift (RWGS) reaction is a technology that converts carbon dioxide (CO₂) into carbon monoxide (CO) and water (H₂O) by reacting it with hydrogen (H₂) in a reactor. The resulting carbon monoxide can be combined with the remaining hydrogen to produce syngas, which serves as a building block for synthetic fuels such as e-fuels* and methanol. This makes the RWGS reaction a promising technology for driving the eco-friendly fuel industry.

* E-Fuels are synthetic fuels produced by combining green hydrogen, generated with renewable electricity, and captured CO₂ from the atmosphere or sustainable biomass. They are emerging as a promising alternative to conventional fossil fuels, especially for hard-to-decarbonize sectors such as aviation and shipping.

The reverse water–gas shift (RWGS) reaction achieves higher carbon dioxide conversion at temperatures above 800 °C, and thus nickel-based catalysts, known for their superior thermal stability compared to other metals, are typically employed. However, prolonged exposure to such high temperatures causes particle agglomeration, leading to reduced catalytic activity. At lower temperatures, byproducts such as methane are formed, which decreases carbon monoxide productivity. Therefore, current research is focusing on developing catalysts that maintain high activity even under low-temperature conditions, in order to reduce process costs and improve efficiency.

The KIER research team has overcome the limitations of conventional catalysts by developing a cost-effective and abundant copper-based catalyst. Their newly developed copper–magnesium–iron mixed oxide catalyst successfully produced carbon monoxide 1.7 times faster and with 1.5 times higher yield than commercial copper catalysts at 400 °C.

Unlike nickel catalysts, copper-based catalysts can selectively produce only carbon monoxide at temperatures below 400 °C without generating byproducts such as methane. The challenge, however, is that copper’s thermal stability decreases significantly at around 400 °C. Reduced thermal stability leads to particle agglomeration, which markedly diminishes the overall stability of the catalyst.

To address this issue, the research team implemented a layered double hydroxide (LDH) structure. This structure has a sandwich-like form, where water molecules and anions are intercalated between thin metal layers, and by adjusting the types and ratios of metal ions, various physical and chemical properties can be achieved. By incorporating iron and magnesium, the team was able to fill the spaces between copper particles, preventing particle agglomeration and thereby enhancing thermal stability.

Through real-time infrared analysis and reaction experiments, the researchers identified why the newly developed catalyst outperforms conventional ones. When using traditional copper catalysts, carbon dioxide and hydrogen first react to form formate intermediates, which are then converted into carbon monoxide. In contrast, the new catalyst was found to directly convert carbon dioxide into carbon monoxide on the catalyst surface without generating intermediates. Because it avoids producing unnecessary intermediates or methane byproducts, the catalyst maintains high activity even at the relatively low temperature of 400 °C.

The catalyst developed by the research team achieved a carbon monoxide yield of 33.4% and a formation rate of 223.7 micromoles per gram of catalyst per second (μmol·gcat⁻¹·s⁻¹) at 400 °C, while operating stably for more than 100 hours. This performance represents over a 1.7-fold increase in carbon monoxide formation rate and a 1.5-fold increase in yield compared to commercial copper catalysts. Furthermore, when compared to noble metal catalysts such as platinum, which exhibit high activity at low temperatures, the new catalyst demonstrated a 2.2-fold higher formation rate and a 1.8-fold higher yield, marking it as one of the best-performing catalysts worldwide.

Dr. Kee Young Koo, the lead researcher, stated, “The low-temperature CO₂ hydrogenation catalyst technology is a breakthrough achievement that enables the efficient production of carbon monoxide using inexpensive and abundant metals. It can be directly applied to the production of key feedstocks for sustainable synthetic fuels. Moving forward, we will continue our research to expand its application to real industrial settings, thereby contributing to the realization of carbon neutrality and the commercialization of sustainable synthetic fuel production technologies.

The research findings were published online in May 2025 in Applied Catalysis B: Environmental and Energy (Impact Factor: 21.1), a leading journal in the field of energy and environmental catalysis. The study was supported by the KIER’s R&D project, ‘Development of e-SAF (sustainable aviation fuel) production technology from carbon dioxide and hydrogen.