Influence of the reduction temperature on catalytic activity of Co/TiO ₂ (anatase-type) for high pressure dry reforming of methane

0.5 wt.% Co/TiO₂ was prepared by incipient wetness impregnation with Co(NO₃)₂·6H₂O and TiO₂, which contains only anatase as crystal structure. The influence of reduction temperature (973-1223 K) on the catalytic activity of the 0.5 wt.% Co/TiO ₂ was investigated for the CH₄/CO₂ reaction under 2.0 MPa mainly at a space velocity (SV) of 6000 mlg^-1h ^-1. Co/TiO₂ reduced below 1123K lost its activity completely at the beginning of the reaction. The results of TPO revealed that large amounts of coke (≧2.9wt.% carbon for 24 h) were deposited on the catalysts during the CH₄/CO₂ reaction. On the other hand, Co/TiO₂ reduced at and above 1123 K kept relatively stable activity for 24h and did not show significant amounts of deposited coke (≦0.25 wt.% carbon). The natures causing different catalytic behavior among the catalysts were discussed with the results of TEM, XRD, and TPR. In addition, slow deactivation of the Co/TiO₂ reduced at 1123K, probably due to the oxidation of the metallic cobalt, was inhibited by the addition of small amount of ruthenium (Ru/Co = 0.05) and it was found that the strong resistance to the coking of the Co/TiO₂ reduced at 1123K was retained after the addition of ruthenium.