大豆甾醇的热解及热动力学研究

摘要

用TG-DTG/DTA方法研究了大豆甾醇热解过程及热动力学.热重法(TG)和微分热重法(DTG)分析结果表明该物质的失重过程分3步进行.第1阶段为结晶水脱出,第2步为其分子骨架大规模降解和挥发,第3阶段为残余物的缓慢降解.热解过程中,加热速率对大豆甾醇热解有显著作用.使用Popescu计算大豆甾醇为119kJ/mol,并用FWO和KAS方法进行验证.通过对常用41种热解动力学机理函数线性分析,确定了大豆甾醇热解过程最适合机理函数为Mample单行法则g(α)=-ln(1-α).%Pyrolysis characteristics and kinetics of the soybean sterol were studied with TG - DTG/DTA method. The TG - DTG curve showed the process of mass loss of the substance proceeded in three steps. The first stage could be attributed to the expulsion of water of crystallization. The second stage was corresponding to the large scale degradation and decomposition of the molecular structure. And the residue was slowly degraded in the third stage. Heating rate had a significant effect on the pyrolysis of the soybean sterol. The activation energy E of the second stage of degradation process obtained by Popescu was 119 kJ/mol. According to Popescu mechanism functions,the possible kinetic model for soybean sterol was estimated to be Mample Separate Law g(α) =-ln(l -α).