Production of Stable Biomass Pyrolysis Oils Using Fractional Catalytic Pyrolysis

Pyrolysis of biomass is developing rapidly and could play a very important role in the future renewable energy equation. However, rapid pyrolysis oils are usually acidic and unstable and have high viscosities, which increase with storage time. We have developed a fractional catalytic pyrolysis process that produces stable, low-viscosity biomass pyrolysis oils that can be stored at ambient conditions without any significant increase in viscosity. The oils can be distilled at both atmospheric pressure and under vacuum without char or solid formation. Fractional catalytic pyrolysis oils produced from hybrid poplar wood were stored at ambient laboratory conditions for more than 10 months, and the dynamic viscosities changed from 11.2 +/- 0.45 to 12.7 +/- 0.56 cP. The oils were characterized using the high-temperature simulated distillation method, and this showed 100% distillation at up to 640 degrees C (1200 degrees F). The total acid number (TAN) for the stable pyrolysis oil was 41.02 +/- 0.89 mg of KOH/g of oil compared to 91.01 +/- 1.89 mg of KOH/g of oil for the conventional pyrolysis oil.