Transformation behavior of potassium during pyrolysis of biomass

The present work studied the transformation behavior of K involving the change of water-insoluble K and K₂CO₃ during biomass pyrolysis. KCl-loaded cellulose samples were used as fuels with the aim to determine the key reactions involved during K transformation. For comparision, KCl-loaded char samples were used as fuels to eliminate the effect of organics in cellulose on K transformation. The total amounts of K, and water-soluble K, Cl^-, and CO₃^2- in the fuels and in the obtained solid residues were quantified. The quantification results indicated that, during the pyrolysis of the KCl-loaded cellulose, the reactions between KCl and active functional groups which are produced from organic matter in cellulose during pyrolysis lead to a certain amount of water-insoluble K formed above 300 °C and the water-insoluble K was transformed into K₂CO₃ above 600 °C. The reactions between KCl and the organic matter in the cellulose were governed by both the availability of active functional groups produced during cellulose pyrolysis and the amount of KCl. The presence of O₂ promoted the generation of K₂CO₃.