XPS and TPR Studies of Nitrided Molybdena−Alumina

The relationship between the surface molybdenum species and adsorbed nitrogen species on nitrided 1.0−18.7% MoO 3 /Al 2 O 3 was elucidated by XPS and temperature-programmed reduction (TPR). The MoO 3 /Al 2 O 3 samples were nitrided by temperature-programmed reaction with NH 3 . From the XPS analysis, Mo 3+ and Mo 4+ ions were predominant on the surface of the nitrided Mo/Al 2 O 3 samples. From the TPR measurement, the ammonia desorption was due to nitrogen species adsorbed on alumina. The nitrogen desorption was due to two kinds of nitrogen desorption from the structures of γ-Mo 2 N and β-Mo 2 N 0.78 and four kinds of nitrogen desorption from NH X species adsorbed on MoO 2, Mo 3+ ion (γ-Mo 2 N), Mo 2+ ion (molybdenum nitride on alumina such as highly dispersed molybdenum nitride), and alumina.