Development of an Ir/TiO₂ catalytic coating for plasma assisted hydrogenation of CO₂ to CH₄

The hydrogenation of CO₂ to methane over a 20 wt% Ir/TiO₂ catalytic coating has been investigated in a tubular dielectric barrier discharge (DBD) reactor. The 1.2 µm Ir/TiO₂ coating was deposited onto the inner wall of a quartz tube by a combustion-evaporation method from a mixture containing a Ti precursor and a colloidal suspension of Ir nanoparticles (2 nm). The catalyst was characterised by XRD, SEM, TEM/EDS and CO chemisorption. The Ir(0) state in the as-synthesised film was confirmed by XPS. The CH₄ conversion increased by 1.5 times, as compared to an empty tube. A maximum CO₂ conversion rate of 2.1 μmol s⁻¹ was achieved at a fuel production efficiency of 3.5%. Surface reactions onto the catalyst surface are responsible for enhancement of reaction rate. The results presented in this work open up new possibilities in plasma-catalysis, whereby efficient reactions can be carried out over small volumes of catalyst.