Pyrolysis of Coals and Biomass: Analysis of Thermal Breakdown and Its Products

A survey of experimental data and analytical tools that have served to formulate a conceptual model of thermal breakdown processes taking place during pyrolysis of middle-rank coals and lignocellulosic biomass is studied. When solid fuels are heated beyond their characteristic threshold thermal breakdown temperatures, irreversible chemical and physical changes are initiated. These processes constitute the first stage of all solid fuel utilization processes, including combustion, coking, liquefaction, and gasification. The thermal breakdown phenomena are intimately related to processing routes for making synthetic liquids from diverse starting materials that include biomass to liquids (BTL), natural gas to liquids (GTL), coal to liquids (CTL), and wastes to liquids (WTL), collectively referred to as feed to liquids (XTL). The size distribution of polynuclear aromatic ring systems is a key parameter that would be useful to evaluate at successive stages of thermal breakdown processes.