Scientists developed a super-dry reforming process using SOECs and Rh-CeCO2₋ₓ catalysts to efficiently convert CO2-rich methane into syngas with high conversion rates and nearly 100% selectivity.
Dry reforming of methane (DRM) is a well-established method for converting carbon dioxide (CO₂) and methane (CH₄) into synthesis gas (syngas), which is a valuable mixture of hydrogen (H₂) and carbon monoxide (CO). This process is typically conducted with a feed ratio of CO₂ to CH₄ close to one. However, future methane sources such as carbon dioxide-rich natural gas are expected to contain much higher levels of CO₂. These elevated concentrations often require costly separation processes in order to reach the desired methane content.
In a study published in Nature Chemistry, a research team led by Professors Guoxiong Wang, Jianping Xiao, and Xinhe Bao from the Dalian Institute of Chemical Physics at the Chinese Academy of Sciences introduced an innovative method for directly producing syngas. This process, referred to as super dry reforming of methane, operates with a CO₂ to CH₄ ratio equal to or greater than two. It enables direct conversion of CO₂-rich natural gas through high-temperature tandem electro-thermocatalysis using solid oxide electrolysis cells (SOECs).
These electrolysis cells function at high temperatures ranging from 600 to 850 degrees Celsius and are capable of converting carbon dioxide and water into carbon monoxide and hydrogen. Their advantages include high reaction rates, strong energy efficiency, and relatively low operating costs. As a result, they offer significant potential for carbon dioxide utilization, hydrogen production, and renewable energy storage.
Recognizing the compatibility of operating temperatures between SOECs and DRM, the researchers designed a process that combines DRM, the reverse water-gas shift reaction, and water electrolysis within the cathode of the electrolysis cell.
A Coupled Electrochemical System
In this setup, the in situ electrochemical reduction of H2O byproduct generates H2 and O2- ions. These O2- ions then migrate through the electrolyte and are electrochemically oxidized to O2 at the anode under an applied potential. This process drives the RWGS equilibrium forward, enhancing CO2 conversion and H2 selectivity beyond conventional thermodynamic limitations.
Moreover, researchers in situ exsolved Rh nanoparticles onto a CeO2-x support, creating high-density Ce3+-VO-Rhδ+ interfacial active sites. When operating at a CO2/CH4 ratio of 4, the system achieved CH4 conversion of 94.5% and CO2 conversion of 95.0%, with nearly 100% selectivity toward CO and H2. The apparent methane reducibility reached the theoretical maximum of 4.0.
Further investigation revealed that Rhδ+ sites are primarily responsible for CH4 dissociation, while the Ce3+-VO-Rhδ+ interface—rich in oxygen vacancies—promotes CO2 adsorption, activation, and the RWGS reaction. This same interface also catalyzed electrochemical H2O reduction, boosting both CO2 conversion and H2 selectivity.
“Our study may open a new avenue for the direct utilization of CO2-rich natural gas and industrial tail gases using renewable energy,” said Prof. Wang.
Reference: “Super-dry reforming of methane using a tandem electro-thermocatalytic system” by Houfu Lv, Xue Dong, Rongtan Li, Chaobin Zeng, Xiaomin Zhang, Yuefeng Song, Haolin Liu, Jiaqi Shao, Na Ta, Qiao Zhao, Qiang Fu, Jianping Xiao, Guoxiong Wang and Xinhe Bao, 21 March 2025, Nature Chemistry.
DOI: 10.1038/s41557-025-01768-1
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