Preparation of β-Mo₂C, Ni₃Mo₃N/β-Mo₂C and its catalytic performance for methanation

A complexes was produced using hexamethylenetetramine(HMT) as the complexing agent of ammonium molybdate, and β-Mo₂C was prepared by a simple thermal decomposition of this complexes. And then Ni was introduced and the bimetallic carbide Ni₃Mo₃N/β-Mo₂C was prepared. The as-prepared products were characterized by XRD, low-temperature nitrogen adsorption, SEM, HRTEM, element analysis (EA), and the performances of the prepared catalysts for methanation were investigated. The results showed that the bulk molybdenum carbide exhibited high conversion of CO (x_CO), but x_CO and selectivity of CH₄ (s_CH4) on β-Mo₂C decreased from 75.93% and 36.79% to 67.41% and 33.54% within 100 h. Thus the catalytic activity was not stable and s_CH4 was low. The addition of Ni markedly promoted the catalyst activity and stability, x_CO and s_CH4 on Ni₃Mo₃N/β-Mo₂C increased from 83.15% and 46.64% to 92.51% and 57.23% within 100h, which should be attributed to the newly produced Ni₃Mo₃N after Ni addition.