Tuning carburization behaviors of metallic iron catalysts with potassium promoter and CO/syngas/C2H4/C2H2 gases

Iron carbide phase formation during carburization of α-Fe catalysts were studied using in situ XRD, where the effect of varying carbon chemical potentials of CO/syngas/C 2 H 4 /C 2 H 2 gases and potassium promoter on the carburization behaviors was studied. The actual carburization capability of these gases follows an order of 2% CO/He 2 H 4 /He 2 /He 2 H 2 /He, which does not correlate well with the theoretical carbon chemical potential. In addition, the carburization rate and the formation of carbon-rich iron carbides are favored by potassium under CO or syngas, while inhibited by potassium under C 2 H 4 or C 2 H 2 . Temperature programmed carburization together with pulse experiments and DFT calculations indicate that the potassium promoter could weaken the adsorption ability of the C 2 H 4 and C 2 H 2 and thus reduce their carburization capabilities.