(738b) Effect of Feedstock and Pyrolysis Method on the Yield of Hydrotreated Refinery Intermediate

Biomass can be converted into a hydrocarbon mixture with properties similar to refinery intermediates such as naphtha or gas-oil via fast pyrolysis followed by hydrotreating of the pyrolysis liquid. However the feedstock affects the yield and properties of the pyrolysis liquid in ways that are not well understood. The properties of the pyrolysis liquid in turn affect the operability of the hydrotreating and the number of stages required to accomplish the hydroprocessing. Catalytic upgrading of the fast pyrolysis vapors produces a higher quality pyrolysis oil but in lower yield than the non-catalytic method. Thus the most carbon efficient, energy efficient, and cost-effective path for a given feedstock is still in question.

Therefore Idaho National Laboratory (INL), the National Renewable Energy Laboratory (NREL), and Pacific Northwest National Laboratory (PNNL) have been collaborating to study the effect of feedstock properties and vapor-phase upgrading (VPU) on the yield and quality of the hydrotreated products. INL has provided feedstocks, NREL has performed pyrolysis/VPU, and PNNL has hydrotreated the liquids. Preliminary results suggest that air classified forest residue is a promising low-cost waste stream and miscanthus is a promising energy crop for these processes. Modeling has identified lignin, volatile matter, and alkali content of the biomass as key predictors of pyrolysis yield.

Ongoing work is exploring the effect of the type of lignin and modeling the effect of oil properties on the hydrotreating.