(410h) Bifunctional Porous Materials for Combined CO2 Capture and Catalytic Conversion

The rapidly-increasing concentration of Greenhouse Gases (GHGs) in the atmosphere has become a critical issue prompting the scientific and engineering community to find ways to efficiently mitigate emissions of GHGs, such as CO₂. Electricity generation using fossil fuels is one of the major contributors of CO₂ emissions and therefore, various end-of-the pipe technologies are currently proposed as carbon management media. A less energy intensive alternative than amine-based solvents are solid adsorbents which are capable of CO₂ capture at low temperatures as part of the Carbon Capture Utilisation and Storage process (CCUS). Another interesting development in CCUS research is the use of captured CO₂ as a chemical feedstock. Although this pathway will not eliminate the need for long term CO₂ storage, carbon utilisation could diversify the range of possibilities

Metal-organic frameworks (MOFs) represent a class of adsorbents with chemical and structural tunability, large porosity as well as high thermal and chemical stability. Owing to these features, MOFs are promising materials for CO₂ capture. In addition, recent research efforts point to the potential use of MOFs as photocatalysts, especially in the context of CO₂ reduction into useful products (e.g. CO and CH₄). Considering these two aspects, we are investigating the application of MOFs as bifunctional absorbent-photocatalyst materials for the combined capture and conversion of CO₂. This approach could potentially enable process intensification and improvement of the overall Carbon Capture Utilisation and Storage process sustainability. A series of MOFs were synthesised and fully characterised by a range of analytical and spectroscopic techniques (i.e. XRD, FT-IR, thermogravimetric analysis, N₂ sorption). These MOFs were tested as CO₂ adsorbents as well as heterogeneous CO₂ reduction photocatalysts in the gas phase using a purpose-built reactor. In the latter case, H₂ and H₂O as sacrificial agents under mild reaction conditions (ambient temperature and pressure). Products were analysed using a GC-MS and the MOFs were characterised after testing to identify any change in structure and/or chemistry. The results were used to identify mechanisms of reactions.