| Biomass energy is a very important part of the renewable energy. The biomass resources are very abundant in the world, and are inexhaustible and sustainable sources of energy. Their reasonable and high efficient utilization will be playing a positive role for resolving the crisis of energy resources and the improving human existence environment. Thermochemical conversion is the major way for high efficient utilization of biomass and is a hot point of research both in China and abroad. This thesis discussed the results of comparative analysis from four different planes, namely the behaviors properties of fast pyrolysis, pyrolytic dynamics, directional catalytic gasification and the engineering adaptability of catalytic gasification technology. Based on the fundamental and engineering technology research, the reaction properties were described for gasification mechanism and fast pyrolysis behavior of thermochemical conversion of biomass.1. In resent 10 years, the fast pyrolysis of biomass is the focal point of applied research of thermochemical conversion. By the way of fast pyrolysis, biomass is converted into bio-oil as the substitute of petroleum liquid fuel. The thesis studied the correlation of fast pyrolysis technology with the change of output and composition distribution for the solid, liquid and gas products. The results indicated: At the same rate of rising temperature and stay time in reactor, with the raising of pyrolysis temperature the quantity of thermal decomposition gas is increased, and the liquid and solid products are reduced. The reducing rate of solid products is lower than that of liquid products. The output of liquid phase is the highest at about 500℃. This is in the temperature region of lignin pyrolysis, and should be the optimum temperature to make the liquid product from biomass. During the fast pyrolysis reaction, the retention time of decomposition products in reactor should be short as far as possible in order to increase liquid product and avoid its second and further splitting decomposition. At about 550℃, The main chemical compounds of the liquid product are 2,6-Dimethoxyphenol, 2,6-Dimethoxy-4-methyl phenol, 4-Methylsyringol etc and a few of formic acid. As the temperature goes up to 850℃, in the reaction products the monomerphenol and a large number of low molecular chemical compounds, such as butanone,formic acid,acetic acid,ethanol, butyric acid and glycerin etc are appeared.The gas product of fast pyrolysis is mainly composed of CO and CO2, which occupy about 80% in whole gas, and the others are some of CH4 and CnCm etc. The change of content and quantity of gas is related with the rising temperature speed and retention time of pyrolysis products in reactor. The high reaction temperature and the long retention time will be favour of producing the gas product. The purpose of this research chiefly is to get high liquid product yield, so the technology of low temperature and the shortest retention time is preferred.2. The test results of the study on the chemical reaction dynamics of biomass pyrolysis showed: Under the condition of different rising temperature speed, the reaction mechanism and process of biomass pyrolysis is changing. When rising temperature speed is 4.2℃ /min and 40℃/min, both TG-DSC-T curves have an affinity part , emerging out the clear peak of exothermal reaction. For rising temperature speed of 4.2℃/min and the reaction temperature over 390℃, the chemical reaction dynamics model can not be expressed by the traditional mathematical model and the reaction rate is appeared in a linear relation with reaction temperature. During heating speed of 40℃/min, the curve of turns scopes (at 385～490℃) also can not be expressed with the mathematical model formula used usually. But for the reaction temperature in the scope of 490～700℃, the reaction process can be expressed using mathematical model, and the correlation of linear regression is very good. The reaction activation energy E=29.53 KJ/mol and is greatly lower than t...
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