Upgrading pyrolysis bio-oil to hydrocarbon enriched biofuel over bifunctional Fe-Ni/HZSM-5 catalyst in supercritical methanol

- Integration of Fe-Ni/HZSM-5 and supercritical methanol was used for bio-oil HDO.
- Fe-Ni/HZSM-5 exhibited better performance than Fe/HZSM-5 or Ni/HZSM-5.
- Fe-Ni(2)/HZSM-5 produced biofuel with the highest hydrocarbons content at 28.60%.

Although hydrodeoxygenation (HDO) is proven a promising process for upgrading pyrolysis bio-oil to hydrocarbon biofuel, catalyst efficiency remains a challenge. Integrating heterogeneous catalysts with supercritical liquid in a bio-oil HDO process was investigated in this study. Bifunctional Fe-Ni/HZSM-5 catalysts were firstly used to upgrade bio-oil to hydrocarbon biofuel in supercritical methanol. The loading of Fe and Ni did not change HZSM-5 crystalline structure, but BET surface area and total pore volume of Fe-Ni/HZSM-5 catalysts decreased significantly compared to HZSM-5 support. Physicochemical properties of biofuel produced by Fe and/or Ni loaded HZSM-5 catalysts such as water content, total acid number, viscosity and higher heating value improved in comparison with raw bio-oil. Bimetallic Fe-Ni/HZSM-5 catalysts were more effective for bio-oil HDO compared to monometallic Fe/HZSM-5 or Ni/HZSM-5 catalyst, and this was attributed to the synergistic effect of Fe and Ni on HZSM-5 support. Fe-Ni(2)/HZSM-5 catalyst produced biofuel with the highest hydrocarbon content at 28.60%.