Noble-Metal-Free, Nickel-Based Dual Functional Materials for Improved Methane Production from In Situ Carbon Dioxide Capture and Conversion

Abstract

Promoters for dual functional materials have not been well explored, but promoters could improve the efficiency of the process by improving the selectivity of the CO₂ methanation process. Utilizing integrated capture and conversion, where CO₂ is captured and converted to useful products, would allow for a useful avenue to control CO₂ emissions. One such way to accomplish this would be to utilize materials that can both capture and convert CO₂ to useful products. However, these materials are often based on costly noble metals, like ruthenium and platinum, decreasing their viability on an industrial scale. Less expensive metals, for example, nickel, would allow for dual functional materials to be more readily utilized in industrial settings. Nickel-based dual functional materials often do not react with the captured CO₂ and merely desorb the CO₂ rather than form a useful product. However, promoters have not been well explored for these types of materials to improve the catalytic properties, which would be beneficial to improve nickel-based materials. Herein, we report the addition of ytterbium on a nickel-based dual functional material and the improvements to the production of methane from captured CO₂ with the incorporated ytterbium promoter. The ytterbium promoter improves the selectivity of the catalysts for the hydrogenation of captured CO₂ to methane and increases the ability for the material to capture CO₂ due to additional basic sites being formed on the surface of alumina. The 12%Ni/4%Yb/6%Na₂O/Al₂O₃ catalyst was utilized to capture carbon dioxide and then convert the captured CO₂ to methane over five cycles, where both the amount captured and the amount converted remained stable, indicating the stability of the material over long-term use.