Petrochemicals from Bark by Fluidized Bed Pyrolysis

Abstract

Coniferous bark, composed of 46,3 wt% carbon, 5,7 wt% hydrogen, 47,2 wt% oxygen and 0,8 wt% nitrogen, was pyroly-zed within a temperature range of 700 to 920 °C. The influence of the process parameters on the product spectrum was investigated. The goal was to receive high amounts of a synthetic gas, aromatics and charcoal. A laboratory size fluidized bed with a capacity of 1 to 5 kg/h was built and used for the continuous process. The main fractions are gases, making up 56 to 62 wt%, and charcoal, affording 17 to 22 wt%.

The gas fraction contains about 49% CO, 27% H₂, 15% CH₄, and 9% CO₂ (in vol.%) and is by this a valuable synthetic gas. The defunctionalisation of liquid wood components (5 wt%) is high; main products are benzene and naphthalene.

The dependence of the product composition on the temperature is not very strong. The amount of CO₂ decreases with increasing temperature. The charcoal has a good adsorption quality. The investigations have shown that the pyrolysis of bark, under exclusion of air, in a fluidized bed process is able to produce simple and useful products.