Capture and Methanation of CO₂ Using Dual-Function Materials (DFMs)

Conversion of carbon dioxide (CO₂) captured from flue gases into synthetic natural gas (SNG) aims to create a closed carbon cycle, where excess H₂ produced from renewables is utilized to transform CO₂ released from existing conventional power plants into a reliable and high energy density carrier, that is CH₄. In the last five years, extensive research effort has been dedicated to the synthesis and optimization of composite materials for the realization of this process. These materials, also known as dual-function materials or DFMs, typically consist of an alkaline metal oxide or carbonate phase, along with a Ru or Ni metallic phase supported on a high surface area carrier. The DFMs incorporate both sorptive and catalytic capabilities, capturing the CO₂ in the initial sorption step and then converting it into CH₄ upon H₂ inflow. The dispersion of the sorptive and catalytically active phases, the CO₂ affinity of the alkaline phase, the reducibility of the supported metals and the selectivity towards CH₄ production are some of the parameters influencing their performance. Hereby, we aim to present the most recent works dedicated to the development and optimization of such dual-function materials to be used in the combined capture and the reaction of methanation of CO₂.