Hydropyrolysis characteristics and kinetics of potassium-impregnated pine wood

Abstract

Pine wood biomass (WB) samples impregnated with different potassium contents have been investigated to determine the influence of potassium on their hydropyrolysis behavior. The experiments were carried out using a thermogravimetric analyzer under both N2 and H2 atmosphere, and at the heating rate of 10°C/min from room temperature to 700°C. Results demonstrated that potassium effected on the biomass pyrolysis significantly, as evidenced by the changes in char content and characteristic parameters such as the maximum weight loss rates and the corresponding peak temperatures. The mass of char remaining after pyrolysis significantly increased with the impregnation of potassium acetate, but it did not increase proportionately to the potassium content. The temperature at which the maximum degradation rate occurs shifted to lower temperature, and this effect was more prominent for potassium-impregnated biomass pyrolysis under H2. It was also shown that the potassium had significant catalytic influence on the biomass pyrolysis, but this ability varied with the potassium content. The kinetic analysis indicated that both un-impregnated and potassium-impregnated biomass exhibited two-stage characteristics which could be kinetically described by two consecutive first order reactions. Moreover, the apparent kinetic compensation effect (KCE) has been observed for biomass pyrolysis under both N2 and H2.