CO2 reforming of methane over Ni-Co/ZSM5 catalysts. Aging and carbon deposition study

The wet impregnation method was used to prepare ZSM5 supported nickel and/or cobalt monometallic and bimetallic catalysts with a 7 wt.% total metal loading. The CO2 reforming of methane reaction was carried out in the 600 °C-800 °C temperature range over the different catalysts (GHSV 60000 mL g−1 hr−1). The cobalt containing catalysts favored the reverse water gas shift reaction at high temperature and cobalt acted as a synergist to nickel, as overall, bimetallic catalysts showed better catalytic performance. Carbon deposition was less expressed over catalysts with high cobalt content. Following 12 h on stream at 700 °C, the bimetallic catalyst with cobalt to nickel ratio of 2, showed high CO2 and CH4 conversions (∼60%) accompanied with the lowest carbon deposition (5%). The thermal analysis of aged catalysts showed that among the deposited carbon species, it is the carbon present in the proximity of nickel and/or cobalt catalytic sites that is responsible of deactivation.