A new technology has been developed that can convert carbon dioxide into methane, the main component of natural gas, at room temperature. This breakthrough was published on June 5th in the prestigious journal Nature Nanotechnology.
Professors Jong-Beom Baek from UNIST’s Department of Energy and Chemical Engineering and Hangwon Lim from the Graduate School of Carbon Neutrality announced on the 10th that they have developed a mechanochemical process technology that can efficiently convert carbon dioxide (CO₂) into methane (CH₄) at 65℃. This process is much simpler and consumes less energy compared to high-temperature processes, making it a promising technology for advancing the carbon-neutral era. Generally, the reaction to convert carbon dioxide into methane requires a high-cost process at temperatures between 300-500℃.
The newly developed technology involves placing a catalyst and raw materials into a ball mill apparatus containing small steel balls with a diameter of a few millimeters. The repeated collisions and friction activate the catalyst surface, effectively capturing CO₂ on the catalyst surface and reacting with hydrogen to form methane.
The research team successfully reacted 99.2% of CO₂ at a low temperature of 65℃, and 98.8% of the reacted CO₂ was converted to methane rather than by-products. The technology also showed high efficiency in continuous processes. At an even lower temperature of 15℃, a CO₂ reaction participation rate of 81.4% and a methane selectivity of 98.8% were maintained, demonstrating the potential for commercialization. Unlike batch processes, which wait for reactions to complete, continuous processes continuously input raw materials and output products, making them suitable for industrial mass production.
The nickel and zirconium oxide (ZrO2) catalysts used in the process are commercially available and inexpensive. Nickel splits hydrogen, while zirconium oxide converts CO₂ into an active state that can react with hydrogen. When the oxygen from zirconium oxide is dislodged by the impact and friction of steel balls in the ball mill (creating a vacancy), CO₂ is trapped in this space. The activated CO₂ then reacts with hydrogen split by nickel, converting into methane.
The economic feasibility analysis revealed that the low reaction temperature and the ability to use commercially available catalysts without pretreatment could significantly reduce the cost of process equipment.
Professor Hangwon Lim explained that the majority of costs are from power consumption, which can be reduced to half compared to thermochemical reactions if combined with renewable energy sources like wind or solar power.
This research was conducted in collaboration with Professor Qunxiang Li from the University of Science and Technology of China (USTC) and supported by the National Research Foundation of Korea (NRF) with funding from the Ministry of Science and ICT, along with UNIST’s Carbon Neutral Demonstration Research Center.