Pyrolysis and combustion kinetics of lignocellulosic biomass pellets with calcium-rich wastes from agro-forestry residues

Abstract

The pyrolysis and combustion kinetics of biomass pellets (i.e., rice husk, herb residue, and wood residue) with the calcium-rich wastes (i.e., CaO, CaCO3, and eggshell) from agro-forestry residues were comparatively studied. During pyrolysis or combustion of biomass, the Ca-rich wastes could slightly influence the decomposition rate in the stage of devolatilization at relatively lower temperatures (e.g., <400 °C). However, the lignin decomposition and the char combustion were obviously influenced by the calcium-based catalysis at higher temperatures (>700 °C). Particularly, the eggshell had a lowest activation energy in the stage of char combustion. The presence of alkali and alkaline-earth metals (AAEMs) in the eggshells might have positive effects on volatile and char combustion. During the combustion, the decomposition temperatures of CaCO3 and eggshell were decreased, thereby favoring to uptake CO2. Furthermore, by identifying the small molecular products, it was found that both CaCO3 and CaO can improve the pyrolysis of RH, but CaCO3 showed better performances, especially on CO2 capture at lower temperatures and on the enhancement of CO production.