Influence of CeO₂ on the carbonaceous deposition behavior of Ni-Cu/HZSM-5 catalyst in the hydrodeoxygenation of bio-oil

The influence of CeO₂ as an additive on the carbonaceous deposition behavior of Ni-Cu/H-ZSM-5 catalyst in the hydrodeoxygenation (HDO) of bio-oil was investigated. Various techniques such as thermogravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy were used to elucidate the content and microstructure of carbon deposited on the catalyst surface, the transformation of various forms of carbon (soft carbon, hard carbon and graphite) in HDO, and the kinetics of carbon deposition. The results indicate that the content of CeO₂ added in the Ni-Cu based catalyst and the reaction temperature both have a significant influence on the carbon deposition behavior and the resistance against coking for HDO of bio-oil; for HDO over the Ni-Cu/HZSM-5 catalyst at 270℃, adding 15% CeO₂ gives the Ni-Cu catalyst highest resistance against the carbon deposition.