Investigation of CO Methanation with Different Carbon-Supported Ni-, Fe-, and Co-Containing Catalysts

Catalysts (metaloxide/carbon support) for carbon monoxide methanation were prepared with two different preparation methods using three different metals and three different carbon supports. While nickel (Ni), iron (Fe), and cobalt (Co) were used as metals, graphene oxide, activated carbon and mesoporous carbon were used as carbon support. Two traditional preparation methods, impregnation and co-precipitation, were used in order to prepare the catalysts. The X-ray diffraction, N₂ physisorption, high-resolution transmission electron microscopy, and scanning electron microscopy analysis were used to characterize the catalysts. The CO methanation studies were conducted on all catalysts. The highest surface area results were obtained over the iron oxide composed catalysts. It was found that the impregnation method is the most suitable method for obtaining a high surface area. The average pore diameters of the catalysts entered to the mesopore diameter scale in the Dubinin classification. Except for active carbon-supported iron and cobalt catalysts, other catalysts have crystal phases due to the NiO, Fe₂O_3, and Co₃O_4, according to the composition of catalysts. Activated carbon-supported iron and cobalt catalysts showed an amorphous phase structure. The catalysts prepared by the impregnation method had higher activity. Higher activities were obtained from the graphene oxide supported catalysts. When activities were evaluated in terms of active component (metal oxide) type, cobalt oxide active component provided better results. Co₃O₄/graphene oxide catalyst prepared by the impregnation method leads to 100% CO conversion and 85% CH₄ formation at 275 °C.