Effects of oxidation pretreatment temperature on Kovar used as CO₂ reforming catalyst

The effect of oxidation pretreatment temperature (500~1 000 ℃) on the catalytic activity of Kovar applied on hydrocarbon CO₂ reforming was examined. Catalytic performance evaluation using tetradecane at 800 ℃ with 70 μmol/s CO₂ revealed 700 and 1 000 ℃ as the best pre-oxidation temperature in producing CO and H₂, respectively. XRD and SEM-EDX analyses showed that a separate metal oxide layer composed of iron oxide (Fe₂O₃ and F₃O₄), nickel, cobalt, and possibly their respective oxides started to form when oxidation was conducted at 700 ℃ or higher.The presence of iron enhanced the stability of nickel in the structure while the compact structure of Fe₃O₄ resulted into the formation of a thick and rigid metal oxide layer on the surface of the Kovar tube. The strong physical bond between the metal oxide layer and Kovar tube provided the catalyst good mechanical strength and consequently good catalytic activity.