玉米秸秆木素的化学结构及热解特性

Chemical Structure and Pyrolysis Properties of Cornstalk Lignin

采用木聚糖酶处理与缓和酸水解相结合的分离方法从玉米秸秆皮质部和玉米全秆中分离出木素,所得木素称为EAL木素.用定量核磁共振磷谱(31P-NMR)分析了EAL木素的化学结构,并用热重分析法初步评价了分离木素的热解特性.结果表明:玉米全秆EAL木素主要由愈疮木基单元(G-unit)和对羟苯基单元(H-unit)两种结构单元组成;玉米秸秆皮质部EAL木素主要由对羟苯基单元组成;皮质部EAL木素和全秆EAL木素的失重曲线基本相同;在800.00℃时,全秆木素未被分解的部分占12.38%,而皮质部的占21.06%.

The lignin in cortex and the whole cornstalk was isolated by simultaneously using xylanase and mild acidolysis, obtaining cortex EAL and the whole cornstalk EAL, whose chemical structures and pyrolysis characteristics were then determined respectively by quantitative 31^ P-NMR and thermogravimetry. The results show that the whole cornstalk EAL mainly consists of Guaiacyl unit and p-Hydroxyphenyl unit, while the cortex EAL mainly consists of p-Hydroxyphenyl unit, that the TG and DTG curves of the two EALs are basically the same, and that the undecomposed lignin accounts for 12.38% in the whole cornstalk EAL and 21.60% in the cortex EAL at 800.00 ℃.