Kinetics and mechanisms for catalytic pyrolysis of empty fruit bunch fibre and cellulose with oxides

Abstract

Current study aimed to evaluate kinetic parameters and mechanisms for the thermal degradation of palm empty fruit bunch fibre (EFBF) in presence of calcium oxide (CaO), magnesium oxide (MgO), and zinc oxide (ZnO). These oxides have been proved to improve the bio-oil properties as a catalyst in pyrolysis. In order to achieve the aim, the amount of oxides (0, 5, and 10 wt%) and heating rates (10, 20, 30, and 40 °C/min) are manipulated in thermogravimetric analyses. In addition, cellulose, the most abundant component in EFBF was taken as another feed to understand the changes in kinetic mechanism due to the presence of other lignocellulosic components. The results showed that the incorporation of these oxides, the average activation energy of EFBF lowered in general, where the most significant decrement was observed for the addition of 10 wt% of MgO (274.5 to 194.8 kJ/mol). This reflected that the oxides pose catalytic activities on biomass pyrolysis. However, the oxides (CaO, MgO, and ZnO) would not affect the mechanisms other than catalysing the reactions. Mainly second order chemical reaction and three-dimensional diffusion are the most suitable mechanisms to describe the degradation of EFBF in presence of oxide catalysts. Whereas the cellulose degradation was controlled by 1.5 order chemical reaction and three-dimensional diffusion mechanisms.