稻草和玉米秆热解气体产物的释放特性及形成机理

采用管式反应器与傅里叶变换红外分析(FTIR)联用技术进行了生物质热解特性及主要气体产物释放规律的研究。结果表明，农业生物质热解的主要气体产物有H2O、CO2、CO、CH4、C2H6、C2H4、HCOOH、CH3OH和酚类化合物等。热解过程中先析出游离水，随后发生解聚和脱水反应，主要的C-C键、糖苷键、羰基、羧基、甲氧基和C-O-(C)等基团发生断裂和重整反应，生成CO，CO2、CH4和醇、酸、醛、酚类等物质；在炭化阶段，C-H键和C-O键进一步断裂和芳香化转化，析出CH4、CO2和CO等。在稻草和玉米秆热解过程中，H2O、CO2、CO和CH4有多个析出极值出现，并分别在309和335 ℃达到最大析出峰值。CO和CO2的释放主要集中在220~400 ℃，而CH4的释放主要在较高温度段275~400 ℃，比CO和CO2的析出温度高出55 ℃左右。在220~400 ℃，CO和H2O的释放特性相似。气体产物的释放规律揭示了有关生物质不同组分热行为的重要信息。

Release Characteristics and Formation Mechanism of Gas Products During Rice Straw and Maize Stalk Pyrolysis

The pyrolysis characteristics of typical agricultural biomass were investigated using a tubular reactor coupled with a Fourier transform infrared (FTIR) analyzer. Rice straw and maize stalk were selected as the testing samples and corresponding microstructure was studied. The results indicate that the main gas products are H2O, CO2, CO, CH4, C2H6, C2H4, HCOOH, CH3OH and phenols etc. The FTIR analysis shows that the free water is released out at first during pyrolysis, followed by the depolymerization and dehydration. H2O, CO2, CO, CH4 and alcohols, aldehydes, acids, phenols are mainly generated by the cracking and reforming of functional groups of C-C bond, glycosidic bond, carbonyl, carboxyl, methoxyl, C-O-(C) etc. Aromatization and formation of graphite layers are accompanied by evolution of CO2, CO and CH4. CO and CO2 are mainly released out at 220~400 ℃, however, CH4 mainly evolves out at 275~400 ℃. The releasing behavior of CO and H2O is similar at 220~400 ℃ . The gas evolution patterns reveal important information about the thermal behavior of the various components (cellulose, hemicellulose and lignin) of the biomass.