A photoelectron spectroscopic study of the carburization of MoO3

MoO3 and Mo samples containing copper were treated with different hydrocarbon/hydrogen gas mixtures. The formation of Mo2C was followed by X-ray photoelectron spectroscopy (XPS). Spectra taken in the Mo 3d, C 1s, O 1s, Cu 2p and Cu KLL regions demonstrated that the treatment with the hydrocarbon/hydrogen gas mixtures led to the formation of Mo2C. From the comparison of the effects of various hydrocarbons on the XP spectra of Mo 3d we can state that the reduction of MoO3 starts at the lowest temperature for C2H6/H2 (600 K) followed by CH4/H2 (700 K) and C4H10/H2 (723 K). Binding energies of Mo 3d5/2 characteristic for Mo2C are measured in the range of 227.7-228.0 eV. These values were attained at 900 K for CH4/H2, at 800 K for C2H6/H2 and at 873 K for C4H10/H2. Addition of copper to MoO3 catalyzed its reduction and promoted the carburization process.