Catalysis and Chemical Engineering

Biomass: slow pyrolysis and Fast pyrolysis

Slow pyrolysis at low to moderate temperatures (around 300 °C) and long reaction times (up to days) has been used for thousands of years for the conversion of wood into high yields of charcoal (bio-carbon). The slow pyrolysis process generates also lower yields of bio-oil and gaseous products. However, in the past 30 years, fast pyrolysis, carried out at intermediate temperatures (around 500 °C) and very short reaction times (1 to 5 seconds) has become of considerable interest as a method for producing higher yields of bio-oil (normally around 65 wt%) with significantly higher energy density than the original biomass, in addition to bio-carbon (20%) and gas (15%).

Depending on the pyrolysis  process and on the biomass material utilized, both the yields as well as the physical and chemical characteristics of the products and consequently, their performance, vary considerably.