Wood-based Biomass Catalytic Pyrolysis Kinetics

Iso-thermogravemetric analysis was used in this paper to investigate the pyrolysis characteristics of four kinds of lignocellulosic biomass (pine, poplar, bass and birch) under N2 atmosphere with different conditions. The influences of heating rates, catalysts and co-pyrolysis with coal were discussed.The whole process of pyrolysis of biomass could be divided into three stages, dehydration, devolatilization and carbonation. Devolatilization was the main process which occurred mainly between 200~400℃. The result of dynamic study by Coats-Redfern method showed that the pyrolysis of biomass could be described as first order reaction. The peak temperature increased by 34~40℃, the peak weight loss rate exhibited linear increment and the activation energy increased by 4.14~ 6.86 kJ/mol along with the increasing of heating rate(10,20,40 and 60℃/min). The investigation of pyrolysis catalyzed by Na2CO3 and K2CO3 indicated that the peak temperature decreased by 52.2~69.8℃, the activation energy decreased by 3.8~7.0 kJ/mol and the peak weight loss rate increased by 16.8~25.6% with the increasing of catalyst content from 0 to 10%. The co-pyrolysis of the blend of biomass with coal was investigated. The results showed that biomass and soft coal did not interact chemically under inert conditions, whereas biomass and lignite seemed to interact on each other for the disappearing of the original peak of lignite and biomass and the appearing of a new peak between the peak temperature of biomass and lignite.