Novel molten metal catalysts for CO2-free hydrogen production

Researchers in South Korea have developed an advanced liquid metal catalyst incorporating selenium (Se) to enhance the efficiency of turquoise hydrogen production.

Turquoise hydrogen is generated via methane (CH₄) pyrolysis, producing hydrogen while yielding solid carbon as a byproduct, without emitting carbon dioxide (CO₂).

A research team led by Dr. Seung Ju Han at the Korea Research Institute of Chemical Technology (KRICT) has introduced selenium-doped molten metal catalysts (NiBi, CuBi) to significantly enhance methane pyrolysis efficiency. The technology demonstrates high methane conversion rates and stable catalyst performance, paving the way for sustainable clean hydrogen production.

Methane pyrolysis is a promising eco-friendly hydrogen production method, as it generates solid carbon instead of CO₂ emissions. However, existing approaches face challenges, such as requiring extremely high temperatures or experiencing catalyst deactivation due to carbon deposition on solid catalysts.

To address these challenges, the research team developed a ternary molten metal catalyst incorporating selenium, which enhances catalyst activity and controls bubble formation during the reaction.

Unlike conventional solid catalysts, molten metal catalysts remain in a liquid state, allowing for efficient separation of carbon byproducts and ensuring long-term stable reactions.

Selenium incorporation reduces surface tension, maximizing the contact area between reactant gases and the catalyst, leading to increased hydrogen production efficiency.

Selenium also lowers the activation energy required for methane conversion, thereby improving catalytic performance. Notably, selenium promotes the surface exposure of nickel active sites, further enhancing methane decomposition efficiency.

Selenium addition reduces the surface tension of NiBi-based catalysts by approximately 19%, leading to smaller bubbles and an increased catalyst contact area, significantly improving reaction efficiency. The newly developed selenium-promoted ternary catalysts (NiBiSe, CuBiSe) achieved methane-to-hydrogen conversion efficiencies that improved by 36.3% and 20.5%, respectively, compared to conventional catalysts.

Notably, the NiBiSe catalyst maintained stable performance for over 100 hours, demonstrating exceptional long-term stability.

The research team believes that this breakthrough technology has the potential to accelerate the commercialization of clean hydrogen production. Future research will focus on further improving process efficiency and targeting commercial deployment by 2030.

"This research overcomes key limitations of existing turquoise hydrogen production technologies and is expected to make a significant contribution to achieving carbon neutrality," the researchers stated.

Dr. Yeong-Kuk Lee, President of KRICT, added, "This technology is a core innovation for carbon-free turquoise hydrogen production and will play a crucial role in its commercialization."

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KRICT is a non-profit research institute funded by the Korean government. Since its foundation in 1976, KRICT has played a leading role in advancing national chemical technologies in the fields of chemistry, material science, environmental science, and chemical engineering. Now, KRICT is moving forward to become a globally leading research institute tackling the most challenging issues in the field of Chemistry and Engineering and will continue to fulfill its role in developing chemical technologies that benefit the entire world and contribute to maintaining a healthy planet. More detailed information on KRICT can be found at https://www.krict.re.kr/eng/

This study was published in Applied Catalysis B: Environmental and Energy in December 2024. The research was led by Dr. Seung Ju Han at KRICT and Dr. Jeong-Cheol Seo at the Korea Institute of Industrial Technology, with Ju Ho Son, a researcher at KRICT and Yonsei University, as the first author.

This research was supported by KRICT's core research program and the National Research Foundation of Korea’s Carbon Upcycling Platform Compounds Research Project, funded by the Ministry of Science and ICT.