Fast pyrolysis produces a liquid product that represents ∼70% of the mass of the starting material. However, since the raw oil is highly corrosive, largely immiscible with hydrocarbons, and only partly volatile, it is unsuitable for use in a conventional petroleum refinery or as a finished fuel. Catalytic hydroprocessing can remove oxygen to make a gasoline- or diesel-like product, but the processing costs have not been attractive.
Economic analysis suggests that mild hydroprocessing, leaving 7 wt % oxygen in the pyrolysis oil reduce hydrotreating costs to a range that is more economically viable. If the physical and chemical properties of the mildly hydrotreated products were acceptable, these materials could potentially be available for coprocessing in a petroleum refinery leveraging the economies of scale and existing refining infrastructure to produce a lower-cost product.
Mildly hydrotreated pyrolysis oil with low acidity, good miscibility with hydrocarbons, and high volatility was generated in a semibatch laboratory reactor. A 0.5-L sample was produced at 360°C, 2500 psig hydrogen, with a hydrogen flow of 0.22 sl/g-oil/h and 10 wt % nickel-molybdenum/Al2O3 catalyst. Yields were 36% light product (7% oxygen) and 30% liquid residue. This oil will be subjected to further physical and chemical tests to determine the technical feasibility of co-processing in a petroleum refinery. © 2010 American Institute of Chemical Engineers Environ Prog, 2010.