OP-II-3

PP-III-16INFLUENCE OF MOLYBDENUM ON THE STABILITY OF IRON OXIDEMATERIALS FOR CO FREE HYDROGEN PRODUCTION VIA CYCLICWATER GAS SHIFT PROCESSDatta P. 1 , Rihko-Struckmann L.K. 1 , Sundmacher K. 1,21 Max Planck Institute for Dynamics of Complex Technical Systems,Magdeburg, Germany, E-mail: datta@mpi-magdeburg.mpg.de,2 Otto-von-Guericke University, Magdeburg, GermanyA low temperature fuel cell, e.g. a polymer electrolyte fuel cell (PEFC) does nottolerate high concentrations of carbon monoxide (CO) without significant power loss.Therefore, the removal of CO down to 10-50 ppm in a biomass gasification gas isnecessary if the product gas is used in PEFC. This is conventionally done by highand low temperature water gas shift reactors followed by a selective oxidation unit.Recently, another approach has been suggested, where the CO content has beenreduced in a single reactor, namely by a cyclic water gas shift reaction unit (CWGS)which is based on the periodic reduction and re-oxidation step of Fe 2 O 3 -Ce 0.5 Zr 0.5 O 2[1]. The modified iron oxide is an oxygen storage material which can be used forhydrogen purification. However, such material looses its activity due sintering duringrepeated reduction and re-oxidation cycles. In order to exploit the full potential of thematerial one has to mitigate the sintering of Fe 2 O 3 -Ce 0.5 Zr 0.5 O 2. Our approach in thiscontribution is to add a promoter to the material to stabilize it without compromisingthe oxygen exchange capacity. 80 wt % Fe 2 O 3 with 20 wt % Ce 0.5 Zr 0.5 O 2 wasprepared by urea hydrolysis method [2]. Molybdenum as an additional promoter wasimpregnated into the solid oxide mixture with final elementary Mo content of 1-5 wt%.The chemical composition and the crystalline phase purity were determined byinductively coupled plasma-optical emission spectrometer (ICP-OES) and X-raydiffraction (XRD) respectively. XRD peaks showed the characteristics of Fe 2 O 3 andthe cubic structure of a ceria-zirconia solid solution. The absence of Mo peakssuggests that it exists either as very small crystallites or as a very thin twodimensional film which will not be detected by XRD. However, the presence of Mowas confirmed by the chemical elementary analysis through ICP-OES. Furthermore,reproducibility of the synthesis was checked by the chemical analysis which revealedthat the expected amount of Fe, Ce, Zr and Mo existed in the samples. The sampleswere further characterized by BET surface area, thermo gravimetric analysis (TGA),temperature programmed reduction (TPR), X-ray photo electron spectroscopy (XPS)468