Influence of low CO concentration on catalysed carbon deposition on 20Cr25Ni steel in CO2 environments containing ethene

Carbon deposition on 20Cr25Ni steel at 700 °C has been investigated in CO2-based gases containing 0.7 vol%, 1.0 vol% and 1.4 vol% CO, each with ∼1000vpm C2H4, at 700 °C. Filamentary carbon deposits were formed at the two lowest CO contents but not at 1.4 vol% CO. TEM analyses have shown that the different CO levels change the propensity for deposition by altering the ratio of Ni:Fe in the nanometre sized catalytic particles produced during oxidation.