A photoelectron spectroscopic study of the carburization of MoO_3

摘要

MoO_3 and Mo samples containing copper were treated with different hydrocarbon/hydrogen gas mixtures. The formation of Mo_2C 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 Mo_2C. From the comparison of the effects of various hydrocarbons on the XP spectra of Mo 3d we can state that the reduction of MoO_3 starts at the lowest temperature for C_2H_6/H_2 (600 K) followed by CH_4/H_2 (700 K) and C_4H_(10)/H_2 (723 K). Binding energies of Mo 3d_(5/2) characteristic for Mo_2C are measured in the range of 227.7-228.0 eV. These values were attained at 900 K for CH_4/H_2, at 800 K for C_2H_6/H_2 and at 873 K for C_4H_(10)/H_2. Addition of copper to MoO_3 catalyzed its reduction and promoted the carburization process.