The characterization of cobalt molybdenum nitrides with various cobalt contents has been studied using XRD, TEM, XPS, and temperature-programmed reactions with NH 3 . The hydrodesulfurization of thiophene on the cobalt molybdenum nitride was carried out using a differential microreactor at atmospheric pressure. The XRD analysis of Co( 50)973 indicated that Co 3 Mo 3 N was formed from the nitriding of a CoMoO 4 precursor prepared from Co(NO 3 ) 2 ‚6H 2 O and (NH 4 ) 6 Mo 7 O 24 ‚4H 2 O but not from the mixture of CoO and MoO 3 . Co-(10-25)973 had a high surface area of 120-129 m 2 g -1 , but Co(50)973 had that of 12 m 2 g -1 . The BET surface area was related to the molybdenum ions (Mo 2+ and Mo 3+ ) and cobalt ion (Co 3+ ) in the bulk sample. The XPS and elemental analyses of Co(50)973 showed that the bulk composition was Co 3 Mo 3 N‚N 0.2 and the surface composition was Co 3 Mo 3 N‚N 2 . The cobalt molybdenum nitride Co(0-35)973 was more active than cobalt molybdenum sulfide on basis of catalyst weight in the hydrodesulfurization of thiophene at 623 K.

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The relationship between the surface molybdenum species and adsorbed nitrogen species on nitrided 1.0−18.7% MoO3/Al2O3 was elucidated by XPS and temperature-programmed reduction (TPR). The MoO3/Al2O3 samples were nitrided by temperature-programmed reaction with NH3. From the XPS analysis, Mo3+ and Mo4+ ions were predominant on the surface of the nitrided Mo/Al2O3 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-Mo2N and β-Mo2N0.78 and four kinds of nitrogen desorption from NH X species adsorbed on MoO2, Mo3+ ion (γ-Mo2N), Mo2+ ion (molybdenum nitride on alumina such as highly dispersed molybdenum nitride), and alumina.

The dynamics of a monomer-monomer and a monomer-dimer surface catalytic reaction is investigated. From the mean-field solution, finite systems eventually 'poison' at an exponential rate to a fully occupied, non-reactive state. For the monomer-monomer process, this poisoning is driven by concentration fluctuations of a diffusive nature, leading to poisoning times which vary as a power of the linear system size L. A comparison of the Monte Carlo simulations with the mean-field result suggests that the upper critical dimension for the monomer-monomer model is d, = 2. For the monomer-dimer process, there is an effective potential that needs to be surmounted by fluctuations, leading to poisoning times which grow at least as fast as eL. This gives rise to an apparent reactive steady state.