兖矿油页岩热解特性及热解动力学

Pyrolysis characteristics and pyrolysis kinetics of Yankuang oil shale

利用DSC(热重差热扫描仪)研究兖矿油页岩在不同升温速率5、10、15、20、25、30℃/min下的热质量损失行为,对比分析Coats-Redfern模型、DAEM模型(分布活化能模型)、微分法模型和最大热解速率法4种动力学模型。结果表明兖矿油页岩热解可分为3个阶段:20—200℃,表面水被脱除;200—400℃小分子有机物挥发,出现弱键的断裂,如C—O键和C—S键等;400—600℃出现最大质量损失峰,主要在该温度区域产生油气。Coats-Redfern模型求得的表现活化能E最低为48.33 kJ/mol,最大热解速率法求得的E最高为152.19 kJ/mol。DAEM模型、微分法模型的计算结果处于中间水平,DAEM模型的计算结果为不同转化率下所对应的活化能,其数值随转化率的增大而增大,更符合油页岩热解的实际情况,对于进一步研究油页岩有机质的化学结构特征具有一定的借鉴意义。

Thermogravimetric experiments were conducted on Yankuang oil shale using a thermogravimetric DSC(differential thermal scanner)at different heating rates of 5,10,15,20,25,30℃/min.Coats-Redfern model,DAEM(distribution of activation energy model),differential method model and method of the maximum pyrolysis rate were compared and analyzed.The results show that the pyrolysis of Yankuang oil shale can be divided into three stages:the surface water is removed at 20-200℃,the volatilization of small organic molecules and the breaking of weak bonds,such as C—O and C—S bonds,occurr at 200-400℃,and the peak of the maximum mass loss occurrs at 400-600℃,which is mainly in the region of the temperature where the pyrolysis of the samples produce hydrocarbons.The minimum of the apparent activation energy E obtained by the Coats-Redfern model equals to 48.33 kJ/mol,while the maximum pyrolysis rate method obtains the highest E is equal to 152.19 kJ/mol.The results of DAEM and differential method model are in the middle level.The results of DAEM are the activation energies corresponding to different conversion rates,and its values increase with the increase of conversion rate,which is more in line with the actual situation of oil shale pyrolysis.It is more in line with the actual situation of oil shale pyrolysis,and has certain guiding significance for the further study of the chemical structure characteristics of oil shale organic matter.