Hydrocarbon bio-oil production from pyrolysis bio-oil using non-sulfide Ni-Zn/Al2O3 catalyst

Upgraded bio-oil can partly replace fossil fuels to reduce the environmental issues caused by the massive consumption of fossil fuels. Hydrodeoxygenation is a promising route for upgraded bio-oil production from pyrolysis bio-oil. Non-sulfide catalysts are effective in bio-oil hydrodeoxygenation due to low cost and high activity. Ni-Zn/Al2O3 catalysts were first used to selectively produce hydrocarbon upgraded bio-oil through bio-oil hydrodeoxygenation. Upgrading pine sawdust bio-oil to upgraded hydrocarbon bio-oil was performed using a series of Ni and/or Zn loaded Al2O3 catalysts. The crystalline structure of Al2O3 was maintained after Ni and/or Zn loading, but BET surface area and total pore volume of Ni-Zn/Al2O3 catalysts decreased significantly compared to Al2O3 support. Bimetallic Ni-Zn/Al2O3 catalysts were more effective than monometallic Ni/Al2O3 or Zn/Al2O3 catalyst. Bimetallic 15%Ni-5%Zn/Al2O3 catalyst generated the highest upgraded bio-oil yield at 44.64 wt% and produced the upgraded bio-oil with the highest hydrocarbon content at 50.12%. Physicochemical properties of upgraded bio-oils including heating value, water content and pH were significantly improved in comparison with raw bio-oil. The improved catalytic performance of bimetallic Ni-Zn/Al2O3 catalyst was associated with the synergistic effect of Ni and Zn on Al2O3 support.