Comparison of TG-MS and GC-simulated distillation for determination of the boiling point distribution of various oils

A novel method for the determination of oil boiling point distributions by thermal gravimetric analysis coupled online with a mass spectrometer (TG-MS) is reported. The results obtained by this method differ less than 10% from those obtained by gas chromatography simulated distillation (GC-SIMDIS). Nineteen model compounds with known boiling points, including aliphatic hydrocarbons, aromatic hydrocarbons and heterocyclic aromatic hydrocarbons, were selected to calibrate the TG evaporation curves of oil samples. The initial temperature of cracking reaction when oil evaporates in thermal gravimetric (TG) analysis was determined by online MS signal of small gas products. In this study, the GC-simulated distillation curve of oil is corrected according to the content of aromatic hydrocarbons and aliphatic hydrocarbons in the oil samples. It is found that the optimum heating rate in TG is 5 degrees C/min, and it is necessary to use a capillary as a sample holder to obtain the distillation equilibrium when TG distillation experiment is conducted at atmospheric pressure. Both the initial evaporation temperature and maximum rate evaporation temperature of oil are related to its carbon content. The oil will crack during the evaporation process with an increase in temperature, and there is a linear relationship between the initial cracking temperature and the stable radical concentration of oil.

Automated summary

A novel method for determining oil boiling point distributions by thermal gravimetric analysis coupled online with a mass spectrometer is reported in this study. Results show less than 10% difference compared to those obtained by gas chromatography simulated distillation. The initial temperature of cracking reaction when oil evaporates in thermal gravimetric analysis, and the relationship between the initial cracking temperature and the stable radical concentration of oil were determined.