Effects of catalyst preparation parameters and reaction operating conditions on the activity and stability of thermally fused Fe-olivine catalyst in the steam reforming of toluene

Abstract

An iron-based olivine catalyst synthesized using thermal fusion (TF) was tested in a fixed bed reactor in the steam reforming of a biomass tar model compound. The effects of the catalyst preparation parameters (TF temperature, Fe precursor, Fe-loaded content and olivine support) and reforming reaction operating parameters (reaction temperature and steam to carbon (S/C) molar ratio) on the activity and stability of the TF-olivine catalyst were investigated. The physiochemical properties of the catalyst were analysed, using the following characterizations: X-ray fluorescence (XRF), X-ray diffraction (XRD), Raman spectroscopy, temperature program reduction (TPR) and X-ray photoelectron spectroscopy (XPS). The results showed that a higher TF temperature (1400 °C) promoted the interactions between Fe and olivine supports, part of the Fe was fused into the olivine structure to reorganize a new (Mg, Fe) Fe2O4 phase, which resulted in a high H2 yield and a strong resistance to carbon deposition. Fe2O3-olivine showed the best effect for toluene conversion, while Fe/Ni-olivine presented the best performance for carbon resistance. Fe-olivine showed a strong ability to combine hydroxyls, and the yield of H2 increased with the Fe-loaded content. Toluene conversion increased with the reaction temperature. When the S/C ratio was 1.06, the selectivity of carbon could decrease to 2.71%; meanwhile, the H2 yield decreased slightly with the increase in the S/C ratio. Finally, the stability of TF-olivine catalyst was tested, and no inactivation was observed in the 48-h continuous catalytic reforming experiment.