葵花杆的热解特性及热解产物分析

Pyrolysis Characteristics and Pyrolysis Products of Sunflower Stem

为充分利用生物质葵花杆,采用同步热分析仪以升温速率为影响因素对葵花杆的热解特性进行研究,利用Coats-Redfern积分法计算主要阶段热解动力学参数,并采用气相色谱/质谱联用仪对热解产物进行了定量分析。研究结果表明:葵花杆的热解过程可分为预热干燥、主要热解及炭化3个阶段;随着升温速率的增大,葵花杆热解的TG曲线向高温区移动,残余质量增加;在主热解阶段(125~400℃),葵花杆的失重率约为总失重的85%,活化能(E)37.02~40.48(kJ/mol),指前因子(A)为6.10×102~27.67×10^(2) min^(-1),线性拟合相关系数均大于0.97。快速热裂解过程中检测出106个特征峰、86种特征物质,依据化学种类不同可分为11类,主要热裂解特征产物有硬脂酸(29.991%)、棕榈酸(27.642%)、正十八烷(7.185%)、硬酯酸甲酯(2.239%)、异戊二烯(1.678%)。

In order to make full use of biomass sunflower stalks,the simultaneous thermal analyzer was used to study the pyrolysis characteristics of sunflower stalks with heating rate as an influencing factor.The Coats-Redfern integral method was used to calculate the main phase pyrolysis kinetic parameters.And the quantitative analysis of pyrolysis products were studied by pyrolysis-gas chromatography/mass spectrometry(Py-GC/MS).The results showed that the pyrolysis process of sunflower stalk could be divided into three stages:preheating and drying,main pyrolysis and charring;as the heating rate increased,the TG curve of sunflower stalk pyrolysis moved to the high temperature zone.In the main pyrolysis stage(125-400℃),the weight loss rate of sunflower stalk was about 85%of the total weight loss,the activation energies(E)were 37.02-40.48 kJ/mol,and the pre-exponential factors(A)were 6.10×102-27.67×10^(2) min^(-1),the linear fitting correlation coefficients were all greater than 0.97.During the rapid thermal cracking process,106 characteristic peaks and 86 characteristic substances were detected,which could be divided into 11 categories according to different chemical types.The main characteristic products of thermal cracking were stearic acid(29.991%),palmitic acid(27.642%),n-octadecane(7.185%),methyl stearate(2.239%),isoprene(1.678%).