Study on catalytic properties of potassium carbonate during the process of sawdust pyrolysis

In order to investigate the effect of potassium carbonate on biomass pyrolysis properties, sawdust was used as raw material and different amounts of K₂CO₃ were added by impregnation method to carry out thermogravimetric and pyrolysis experiments. The effects of pyrolysis temperature and the amount of K₂CO₃ addition on the pyrolysis of sawdust were studied using a self-made fixed-bed pyrolysis furnace. Calculation of pyrolysis kinetics shows that the existence of K₂CO₃ catalyst changes the pyrolysis path of sawdust, so that the activation energy of pyrolysis sawdust decreases at low temperature and increases at high temperature. The pyrolysis experiments shows that the addition of K₂CO₃ and the increase of pyrolysis temperature both reduce the yield of the pyrolysis oil of sawdust and increase the yield of the pyrolysis syngas. However, K₂CO₃ catalyst promotes the yield of char, the increase of pyrolysis temperature decreases the yield of char. Analysis of the pyrolysis products finds that the addition of K₂CO₃ and the increase of pyrolysis temperature both improve quality of the pyrolysis oil, form more microporous surface of char, and increase the hydrogen content in the pyrolysis syngas. It is considered that the optimal process for producing pyrolysis syngas is 900 °C of pyrolysis temperature and 10% of K₂CO₃ addition.