Comparative study of Rh/MgO modified with Fe, Co or Ni for the catalytic partial oxidation of methane at short contact time. Part II: Catalytic performance and bed temperature profile

Modifying effects of Fe, Co or Ni over 1 wt% Rh/MgO on the catalytic performance in the catalytic partial oxidation (CPO) of methane were investigated. The optimization of the additive amount was determined by the results of the activity test in the CPO of methane with N-2 dilution. The optimum amount of Co (Co/Rh = 1) or Ni (Ni/Rh =1.5) addition to Rh/MgO enhanced the CH4 conversion and selectivities to H-2 and CO, in contrast, the addition of Fe to Rh/MgO decreased the properties. The results of H-2 titration and H-2 adsorption on the catalysts quenched from the CPO reaction conditions indicate that the RhCo/MgO gave low oxidation degree during the CPO of methane and high resistance to the oxidation was demonstrated. In the CPO of methane without N-2 dilution, Rh-Co/MgO (Co/Rh = 1) had much lower catalyst bed temperatures than other catalysts, and it can suppress the hot spot formation. This property is also related to the high resistance to the oxidation. The catalyst surface is maintained in a reduced state even in the presence of oxygen enables the overlap of the exothermic oxidation zone with endothermic reforming zone and can decrease the bed temperature remarkably. (C) 2010 Elsevier B.V. All rights reserved.