Effects of potassium on solid products of peanut shell torrefaction

To investigate the influencing mechanism of potassium on solid products of biomass torrefaction, peanut shell, a typical agricultural waste in China, was selected as the feedstock and the experiments were carried out in the holding temperature range of 200 similar to 300 degrees C, and in the atmosphere of nitrogen. Based on the water-leaching and impregnation (K2CO3, KCl and K2SO4; impregnation concentration: 0.5%K, 1%K and 2%K) methods, the results showed that the solid product yield of WLPS (water leached peanut shell) torrefaction was higher than that of RPS (raw peanut shell) torrefaction at 200 similar to 300 degrees C. And all these three potassium salts (K2CO3, KCl, and K2SO4) inhibited solid product yields of torrefaction. Potassium existing in RPS was not beneficial for upgrading the organic content during the torrefaction process. The carboxylate was the key intermediate during the biomass torrefaction conversion process. Besides, the activation energy of WLPS (106.28 kJ center dot mol(-1)) was higher than that of RPS (83.34 kJ center dot mol(-1)) during the torrefaction. The impregnated potassium salts reduced the activation energy of WLPS torrefaction process. However, the activation energy of potassium salt impregnated WLPS torrefaction was still higher than that of RPS.