Reaction and characterization studies of an industrial Cr-free iron-based catalyst for high-temperature water gas shift reaction

Activity and stability of an industrial Cr-free iron-based catalyst (NBC-1) for high-temperature water gas shift (WGS) reaction were studied in a fixed-bed reactor under 350 degrees C, 1 atm, H2O:gas = 1:1 and 3000 h(-1) (dry-gas basis). Physical properties of the NBC-1 catalyst before and after the WGS reaction, the desorption behavior of H2O, CO, CO2 and H-2, and surface reaction over the catalyst were characterized by BET, X-ray diffraction (XRD), Mossbauer emission spectroscopy (MES), temperature programmed desorption (TPD) and temperature programmed surface reaction (TPSR). The NBC-1 catalyst is active and has excellent thermo-stability even after pretreatment at a high temperature of 530 degrees C. Its activity and thermo-stability are comparable to those of an UCI commercial Fe-Cr catalyst, C12-4. XRD and MES studies show that iron in the fresh NBG-1 catalyst is present as gamma-Fe2O3, most of which is converted to Fe3O4 during reduction and reaction. Results of TPD demonstrate that adsorbed CO2 and CO cannot exist on the NBC-1 surface beyond the temperature of 300 degrees C while higher temperatures (> 400 degrees C) are required to completely desorb H2O. A redox mechanism of WGS on the NBC-1 surface is proposed based on the TPD and TPSR observations. (c) 2005 Elsevier B.V. All rights reserved.