Thermal Characteristics and Kinetic Analysis of Woody Biomass Pyrolysis in the Presence of Bifunctional Alkali Metal Ceramics

Effects of alkali ceramics, Na2ZrO3 (NZ) and Li4SiO4 (LS), were quantified in the catalytic pyrolysis of sawdust, using thermogravimetric analysis and kinetic modeling. Results indicated that the alkali ceramics were able to initiate thermal decomposition at lower temperatures and enhanced H-2 yield. The mean activation energies estimated by Kissinger-Akahira-Sunose (KAS), Flynn-Wall-Ozawa (FWO) and Friedman methods were within the range of 162-166, 114-116, 112-117 kJ mol(-1) for sawdust (SD), sawdust mixed with Li4SiO4 (SD-LS) and sawdust mixed with Na2ZrO3 (SD-NZ), respectively. The theoretical and experimental master plots constructed for SD closely match with theoretical master plot corresponding to three-dimensional diffusion (Ginstling-Brounshtein equation) (D4) reaction model. The SD-LS and SD-NZ samples followed first-order (F1) reaction model at lower conversions and shifted from F1 to three-dimensional diffusion (D4) reaction model at higher conversions.