Recent Advancements, Fundamental Challenges, and Opportunities in Catalytic Methanation of CO₂

Abstract

Commercial and environmental benefits have made carbon dioxide (CO2) methanation one of the topmost research projects all over the world both at the pilot plant and commercial scale. Mitigation of CO2 via carbon capture and storage (CCS) routes have less motivation from a commercial point of view. Therefore, an integrated system is of paramount importance to convert CO2 into value-added products such as methane (CH4) using solar energy (photosynthesis) or surplus electrical energy in hydrolysis for production of reactant hydrogen to use in CO2 methanation. To date, great efforts have been made to investigate both the reaction mechanism and catalysts development for methanation. Here in this review, up to date references have been cited, which are aimed at giving researchers a comprehensive overview of CO2 methanation with respect to the recent advancements in reaction mechanism, catalytic materials, and the novel combination of metal active phase and its synergy. Both thermochemical and electrochemical routes of CO2 methanation have been discussed, mainly focusing on thermochemical routes. Among the two routes, the thermochemical route seems to be a promising technique for producing an energy carrier due to the high selectivity of CH4.

Recent Developments in the Modelling of Heterogeneous Catalysts for CO2 Conversion to Chemicals

“…The most studied noble and nonnoble metal‐based catalysts for CO 2 methanation are Ni, Ru, Rh, Pd, Co, Fe, Cu, Pt, Ag and Au catalysts from which the most important role to methanation process has Ru, Fe, Ni, and Co . According to the various studies the activity performance and selectivity of different metal‐based catalysts decreases in the following order: Ru>Rh>Ni>Fe>Co>Pt>Pd and Pd>Pt>Ni>Rh>Co>Fe>Ru subsequently . Ni and Ru are reported to have maximum activity and stability .…”

Enhanced low‐temperature activity for CO2 methanation over NiMgAl/SiC composite catalysts

“…The use of an appropriate catalyst is mandatory in CO 2 methanation reaction . Based on the thermodynamic analysis, CO 2 methanation is favored at low temperature because the reaction is highly exothermic . However, the low‐temperature activity of the reported catalysts is still unsatisfactory and new catalysts need to be developed …”

Highly Selective, Iron‐Driven CO2 Methanation

“…While the species that are the most active in CO methanation are also the most active in CO 2 methanation, their activities suffer notably when using CO 2 as the feedstock rather than CO due to its enhanced thermodynamic stability. Furthermore, it has been noted that the activity and selectivity of iron‐based catalysts suffer in particular when applied in direct CO 2 methanation ,. This has been previously attributed to “overbinding” of CO 2 on Fe causing a thermodynamic sink on the reaction coordinate .…”

“…Common industrial methanation catalysts operate via the Sabatier reaction (Equation 1), which is assumed to proceed through one of the proposed direct CO 2 methanation mechanisms, and are thus operated using a feed gas where at P H2 /P CO2 = 4. [7] CO 2 þ 4H 2 Ð CH 4…”

“…Parallel to CO 2 methanation, significant research has also been invested in coupling Reverse Water-Gas Shift (RWGS) and FT chemistry to produce longer chain hydrocarbons beyond CH 4 . In combined RWGS/FT chemistry, CO 2 is initially reduced to CO via RWGS (Equation 2), and the resulting CO is then consumed in FT to produce a distribution of hydrocarbon species (Equation 3): [8]…”