Development of Heterogeneous Catalysts for Upgrading Biomass Pyrolysis Bio-Oils into Advanced Biofuels.

摘要

The massive consumption of fossil fuels and associated environmental issues result in an increased interest in alternative resources such as biofuels. The renewable biofuels can be upgraded from bio-oils that are derived from biomass pyrolysis. Catalytic cracking and hydrodeoxygenation (HDO) are two most promising bio-oil upgrading techniques for biofuel production. Heterogeneous catalysts are essential for upgrading bio-oil into hydrocarbon biofuel. Although some progresses have been made, the cost and effectiveness of catalysts still remain challenges. The main objective of this study was to develop efficient heterogeneous catalysts for upgrading bio-oils into advanced hydrocarbon biofuel with low costs.;In catalytic cracking, Ni/HZSM-5 and Co-Mo/HZSM-5 were used for upgrading bio-oils derived from prairie cordgrass (PCG) and alkali lignin pyrolysis in a two-stage reactor system. 12%Ni/HZSM-5 catalyst yielded the highest amount of gasoline fraction hydrocarbons (32.45%) for PCG bio-oil upgrading. 4%Mo-2%Co/HZSM-5 catalyst showed a robust ability in the PCG catalytic cracking with highest yield of hydrocarbons at 41.08 %. 1.27% NiO/HZSM-5 catalyst generated the highest biofuel yield at 27.5% and produced biofuel with the highest content of hydrocarbons at 69.4 % in alkali lignin bio-oil upgrading.;In hydrodeoxygenation (HDO), Ni based activated carbon catalysts including Ni/AC, Ni-Fe/AC, Ni-Mo/AC and Ni-Cu/AC, and Ni-Zn/Al2O3 catalysts with different Ni and/or Zn loading ratios were designed for HDO of PCG and pine sawdust (PSD) bio-oils. The Ni/AC catalysts produced the highest content of gasoline range hydrocarbons (C6-C12) at 32.63% in PCG biofuel product, while Ni-Mo/AC generated biofuel product with the highest content of gasoline blending alkyl-phenols at 38.41%. 15%Ni-5%Zn/Al2O3 catalyst generated the highest PSD biofuel yield at 44.64 wt.% and the highest hydrocarbon content at 50.12% in biofuel product.;However, the upgrading cost of HDO is still high due to the high consumption of external hydrogen. In this paper, the hydrogen generated from cheap water using zinc hydrolysis for in-situ bio-oil HDO was firstly reported. The effect of different temperatures (200 °C, 250 °C and 300 °C) on PSD bio-oil HDO over Pd/C catalyst was investigated. The results show that 250 °C yielded biofuel with the highest heating value at 30.17 MJ/kg and the highest hydrocarbons content at 24.09%. In bio-oil HDO using zinc metal only, 400°C bio-oil upgrading process produced biofuel product with highest hydrocarbons content at 68.95%.