(729b) Pyrolysis of Biomass Using Blast Furnace Slag As Catalyst

Catalytic pyrolysis of biomass using various acidic zeolite catalysts have shown promise of producing stable biomass pyrolysis oils that can be easily upgraded to fuels and biobased products. However, zeolite catalysts are relatively expensive and tend to produce low liquid yields, large fractions of gas and aqueous phase and therefore there is a need to develop other catalysts that will improve liquid yields. Pine sawdust was pyrolyzed in a bench scale bubbling fluidized reactor using fine blast furnace slag as the pyrolysis medium and nitrogen as fluidizing gas. The pyrolysis was conducted at 500 C and feed rate of 600-700 g/h. The pyrolysis reaction showed an initial exotherm during the first 20 min and there was significant production of hydrogen. The reaction became endothermic like most conventional pyrolysis reactions and hydrogen production decreased. The organic liquid yields ranged from 28 to 48 wt% depending on the run time and were higher than those reported for acidic zeolite catalysts. The char/coke yields ranged from 14 -18 wt%; the non-condensable gas yields ranged from 9 to 13 wt% and pyrolytic water yields ranged from 8 to 18 wt%. The oxygen content of the oils was 27-30 wt%, and the total acid number (TAN) was surprisingly low (23-26 mg KOH/g oil). The oils were less viscous than the sand pyrolysis oils. Thus the blast furnace slag appears to be a promising catalyst for the catalytic pyrolysis of biomass.