Comparison of the regenerability of Co/sepiolite and Co/Al2O3 catalysts containing the spinel phase in simulated bio-oil steam reforming

The catalyst regenerability in steam reforming is vital for achieving the process maturity and commercialization. This work focused on the regenerability of two catalysts containing Co–Al spinel phase during successive reaction-regeneration cycles of simulated bio-oil steam reforming. The Co/sepiolite and Co/Al2O3 derived spinel catalysts were prepared via a thermal-driven solid phase reaction. The catalyst testing cycles consisted of reaction stages performed at 700 °C and subsequent regeneration treatments, which were divided into a coke combustion at 900 °C and a reduction at 800 °C. The deactivation and reproducible performances of catalysts have been ascertained by characterizing the synthesized, deactivated and regenerated catalysts by XRD, TEM, H2-TPR, XPS, Raman and TGA. The results showed that the low activity of Co/Al2O3 was not recovered by regeneration treatments, but attenuated rapidly in subsequent reaction stages due to the high Co–Al spinel crystallinity and deteriorative reducibility. In Co/SEP, the reforming behavior was not fully recovered by coke combustion, correlating with an incomplete restoration of the original spinel structure and an accumulation of cobalt oxides. The recovery of the initial activity and a preferable durability in subsequent reaction stages was attributed to the alleviation of Co sintering after regeneration.