基于TG/DSC-MS和FTIR的纤维素热解特性研究

Research on pyrolysis characteristics of cellulose based on TG/DSC-MS and FTIR technology

为了研究纤维素热解特性,本文利用热重/差示扫描量热法-质谱连用技术(TG/DSC-MS)对纤维素进行热解实验研究,在线监测了热解过程中H_2O、CH_2O、CO_2、醋酸或羟基乙醛、糠醛(质荷比m/z=18、30、44、60、96)几种热解主要产物的演变规律。结果显示,几种物质的最大产率温度遵循H_2O<CH_2O≈CO_2<糠醛<醋酸或羟基乙醛,其中醋酸的生成明显晚于CH_2O和糠醛,表现出不同的生成路径,而CO_2的离子图则出现了明显的双峰,DSC对应的温度(350℃)也出现了吸热峰,可见其生成存在两个阶段。针对甲醛和糠醛两种物质,本文提出了可能的生成路径。此外,本文也利用傅氏转换红外线光谱分析仪(FTIR)表征了不同温度下的热解焦样,半定量分析了几种重要官能团随温度的变化规律。本文揭示了一定纤维素热解进程,为其热转换的工业应用提供了一定的理论基础。

To explore the pyrolysis characteristics of cellulose,TG/DSC-MS technology was applied to pyrolyze cellulose and monitor several main products during pyrolysis,i.e.H2O,CH2O,CO2,acetic acid（or hydroxyl aldehyde） and furfural.The results showed that the temperature of maximum generation rate followed the trend that H2O〈CH2O≈CO2〈furfural〈acetic acid（or hydroxyl aldehyde）.Obviously,the generation of acetic acid（or hydroxyl aldehyde） was later than that of CH2O and furfural,indicating different generation paths of them.And the ion figure of CO2 showed two obvious peaks,one of which was consistent with the peak in DSC at 350 ℃.It seemed that there were two stages for the generation of CO2.For the generation path of formaldehyde and furfural,this work proposed a possible mechanism.Besides,this work also used FTIR technology to characterize the pyrolysis char at various temperature and semi-quantified the evolution of several important groups during pyrolysis.This work revealed some of the pyrolysis mechanism of cellulose and could provide the theoretical basis needed by the industrialized application of cellulose thermal conversion.