Thermal desorption of CO and H2 from degassed 304 and 347 stainless steel

Thermal desorption spectroscopy (TDS), along with Auger electron spectroscopy, was used to study the desorption of H2 and CO from baked 304 and 347 stainless‐steel samples exposed only to residual gases. Both 347 and 304 samples gave identical TDS spectra. The spectra for CO contained a sharp leading peak centered in the temperature range 410–440 °C and an exponentially increasing part for temperatures higher than 500 °C, with a small peak around 600 °C appearing as a shoulder. The leading peak followed a second‐order desorption behavior with an activation energy of 28±2 kcal/mol, suggesting that the rate‐limiting step for this peak is most likely a surface reaction that produces the CO molecules in the surface layer. The amount of desorbed CO corresponding to this peak was ∼0.5×1014 molecules/cm2. The exponentially rising part of the CO spectrum appeared to originate from a bulk diffusion process. The TDS spectrum for H2 consisted of a main peak centered also in the temperature range 410–440 °C, with two...