Effect of potassium on pyrolysis of rice husk and its components

Different rice husk samples and their components (cellulose, hemicellulose and lignin) were investigated with emphasis on the influence of potassium on their pyrolysis behaviors by using thermogravimetric (TG) analysis. The results indicate that the maximum weight loss rate of cellulose decreases with the addition of KCl. However, no significant differences are observed for the pyrolysis behavior of hemicellulose and lignin. The TG/DTG curve of a model rice husk (a mixture of cellulose, hemicellulose and lignin) could be obtained by superposition of that for each component. However, during pyrolysis the raw stable structure of basic components in the rice husk results in a change from a sharp peak for the model rice husk to a shoulder peak for the AW rice husk (pretreated with HCl to remove K and the other mineral matters) at around 300°C. In addition, the effect of KCl addition on pyrolysis of the AW rice husks was also studied. The results show that potassium has a remarkable catalytic effect on pyrolysis of the rice husk samples. The pyrolysis characteristics vary depending on the addition methods of KCl. While char yields decrease with the addition of KCl using mechanical method (except for the cellulose), the char yield and the maximum weight loss rate of impregnated AW rice husk increase gradually with the increase of KCl content.