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 changethe propensity for deposition by altering the ratio of Ni:Fe in the nanometre sized catalytic particles produced during oxidation

The Effect of Temperature and Carbonyl Sulphide on Carbon Deposition on 20Cr25Ni Stainless Steel

In this paper, the results of a systematic study of the effect of temperature and COS concentration on the formation of carbon deposits on a 20Cr25Ni austenitic stainless steel under a depositing gas of 1000 vppm ethene in 1%CO/CO2 have been presented. Carbon deposits were found over the temperature range of 550–725 °C after 4 h exposure. COS additions to the ethene-bearing gas inhibited the deposition process, but the effect was concentration and temperature dependent. The results have been interpreted in terms of the oxidation process and the adsorption of sulphur on the catalytic Ni-rich particles.<br/