Mechanism Study Of Biomass Pyrolysis

To solve the problem caused by energy shortage and environmental pollution, the exploitation and utilization of biomass energy has been paid more attentions during these years. Pyrolysis is not only an independent process for biomass conversion, but also a key stage in biomass gasification and combustion. It is significant to understand the mechanism of biomass pyrolysis. Under the supports of National Natural Scientific Foundation (50025618, 50176046), a detailed research was carryout out to understand the pyrolysis mechanism of biomass.Pyrolysis kinetic study of cellulose, hemicellulose and lignin was done on a thermo-gravimetric balance coupled with a Fourier Transform Infrared spectrometry (FTIR). Kinetic experimental result showed that hemicellulose and lignin had a different shape in the TG and DTG curve from cellulose, while corresponding kinetic parameters were also be calculated. And the influence of salts on biomass pyrolysis kinetics was also investigated.A comprehensive experiments were carried out on a radiation heat reactor to investigate the influence of the reaction parameters on the production of bio-oil, char and gas for the pyrolysis of cellulose, hemicellulose and lignin. Combined with GC-FTIR analysis, experimental result showed that bio-oil produced from cellulose mainly composed of LG and HAA, also of some acid and ketone compounds, bio-oil from xylan mainly composed of acid compounds and aldehyde compounds, while bio-oil from lignin composed of phenol compounds with different functional groups such as methoxyl group, alkyl group, hydroxy group. The difference of pyrolysis characteristic among cellulose, xylan and lignin was studied.For the catalysis importance of metallic salts on biomass pyrolysis, the effect of K~+, Ca~2+, Na~+, and Mg~2+ on the products distribution of biomass pyrolysis was investigated on the radiation reactor by adding metallic salts and followed acid-washing. Metallic salts had more influence on the pyrolysis of cellulose than that of hemicellulose and lignin. And potassium accelerated the cracking and splitting process of large molecules to produce more gas and char.On the basis of TG-FTIR experiments and mechanism study on our radiation reactor, the mechanism of biomass pyrolysis was discussed in detail. And the pyrolysis behavior of cellulose, hemicellulose and lignin was summarized, as is advantageous to future research.