Kinetics of Pyrolysis of Straw Bales by Microwave Heating

The direct pyrolysis of large size biomass is a difficulty, and it seems to be that microwave pyrolysis is a novel process to overcome the problem. This paper presents the experimental results of microwave pyrolysis process for straw bales in a microwave thermogravimetric analyzer the first time. TG and DTG analysis techniques are adopted to study the pyrolysis behaviors of straw bales systematically. The experimental results show that the input power of microwave, heating time and temperature have important effects on pyrolysis process. Reaction kinetics for microwave pyrolysis of straw bale is analyzed theoretically. A one-step comprehensive model is used to describe the microwave pyrolytic reaction in this experiment. The activation energies for the corn and wheat straw under microwave power of 334 and 668 W/ (kg straw) are 24.4, 26.8 kJ/mol and 67.2, 70.3 kJ/mol, respectively, the pyrolytic reaction is first order. The activation energy and pre-exponential factor increase with the increasing of microwave power. The experiment of microwave pyrolysis provides a new method for the wide uses of straws.