碳氢燃料的超临界热稳定性研究

Thermal stability of hydrocarbon fuel under supercritical condition

以正壬烷为碳氢燃料模型化合物,考察其在超临界条件下的恒容热裂解,跟踪裂解转化率和产物分布,探讨了反应温度和时间对燃料热稳定性的影响.正壬烷热裂解气体产物主要有甲烷、乙烷、乙烯、丙烷和丙烯;液态产物中则以链烷烃、烯烃和环烷烃为主,并可检测到芳烃.采用高效液相色谱(HPLC)法测定了液体产物中芳烃的含量,与气相色谱-质谱联用(GC-MS)和紫外-可见光谱(UV-vis)测定结果相互印证,芳烃含量随裂解转化率增加呈指数变化,表达了燃料热稳定性和裂解规律的变化趋势.

The thermal cracking of n-nonane, as a model compound of hydrocarbon fuels, was carried out under supercritical condition in a constant-volume reactor. The influences of temperature and reaction time on the thermal stability of the model fuel were investigated by monitoring the material conversion and product distribution. The predominant components in the gaseous product are methane, ethane, ethylene, propane and propytene. The liquid residues were detected to have the components of paraffins, olefins, naphthenes and even aromatics. The produced aromatic hydrocarbons were determined quantitatively by high performance liquid chromatography （HPLC） and gas chromatography-mass spectrometry （GC-MS）, and also observed by Ultraviolet-visible spectroscopy （UV-vis）. The results from three different methods show satisfactory agreements. It follows that the exponential growth of the aromatics against the increasing conversion of thermal cracking reflects, to a certain extent, the regular changes of the thermal stability and cracking degree of a hydrocarbon fuel.