(56c) Characterization and High Temperature Water Gas Shift Activity Testing of Cu-Doped Transition Metal Doped Ferrites

In the present study, the role of copper on the shift activity of various transition metal doped catalysts is being investigated. The idea was to stimulate the ferrite formation via doping with copper and to promote the Fe³⁺ « Fe²⁺ redox couple during the WGS reaction. For this purpose, various copper doped modified ferrite catalysts of type Fe: M: Cu (M= Cr, Ce, Ni, Co, Mn, and Zn) with the chemical composition 10: 1: 0.25 were prepared by ammonia assisted coprecipitation method. The prepared and activated catalysts were characterized by using X-ray diffraction (XRD), Temperature programmed reduction (TPR), Raman, Mössbauer, and X-ray photo electron spectroscopic (XPS) techniques. The WGS feed condition were chosen to mimic conditions found in a membrane reactor. The WGS reaction conducted in the temperature region 400-550 ^oC and at a Steam/CO ratio 3.5 which the conditions used in our membrane reactor. Interestingly, our shift activity findings reveal that copper act as a promoter for the transition metal doped ferrites expect for the Fe/Ce catalyst. While, Cu acts as an inhibitor for the Fe/Ce catalyst. XRD and TPR results suggest that addition of Cu to Fe/Ce catalyst leads to the formation of wustite phase during the activation. Mössbauer spectroscopy studies indicate that copper selectively enters in to the octahedral sites of the magnetite cubic lattice during the activation of the catalysts and promotes the WGS activity. O1s XPS results show that copper suppress the carbonate formation during the activation of modified ferrites. Cu 2p XPS spectra show that, Cu is not accessible to the surface in the Fe/Ce/Cu catalyst. It is completely incorporated in to the Fe/Ce lattice.