The Chemical Composition and Pyrolysis Characteristics of Thermal Bitumen Derived From Pyrolyzing Huadian Oil Shale, China

Abstract

Thermal bitumen is an important intermediate derived from kerogen decomposition during oil shale pyrolysis. In this study, thermal bitumen was obtained by extracting oil shale char generated from pyrolysis of Huadian oil shale at 360-530 °C. The chemical composition and pyrolysis characteristics of bitumen were investigated by ultimate analysis, liquid chromatography fractionation, Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The decomposition of oxygencontaining structures at 420-450 °C decreased the oxygen content from 4.66 to 0.75 wt%. The intense cracking of aliphatic compounds or alkyl chains at 450-480 °C resulted in the selective concentration of aromatic compounds and the decrease of H/C ratio from 1.350 to 1.262. The pyrolysis of thermal bitumen could be tentatively divided into two stagesthe evaporation of light components (150-410 °C) and the cracking of heavy components (410-550 °C), which corresponded respectively to a shoulder and an obvious peak in differential thermal gravimetry (DTG) curves. For pyrolysis of oil shale, the evaporation process dominated the pyrolysis of thermal bitumen at 420-450 °C, which decreased the content of light components. In a higher temperature range, 450-480 °C, the cracking of large molecules became more intense and, as a result, increased the content of light components and decreased that of heavy components.

Molecular Characteristics of Jimusaer Shale Oil from Xinjiang, China

“…The length of aromatic side chains and the degree of condensation of aromatic rings of the AR and RE are much higher than SA. Additionally, the 13 C-NMR analysis indicated that SA mainly consists of chain alkanes with a few cycloalkanes, whereas AR and RE contain more content of thick-ring aromatic hydrocarbons. R A and R N increase significantly, which indicated that the association degree of RE is significantly higher than those of SA and RE.…”

“…The relative molecular weight was determined by an Agilent-11006 (Agilent, USA) under the conditions of a sample mass of 2 mg, tetrahydrofuran being a solvent, a flow rate of 0.6 mL/min, and a column temperature of 40 °C. Using a Varian Inova-400 superconducting NMR instrument (Varian, USA), deuterated chloroform as a solvent, and tetramethylsilane an internal standard, 1 H-NMR and 13 C-NMR of samples were analyzed at ambient temperature. ■ REFERENCES…”

“…The 1 H-NMR and 13 C-NMR spectra of SA, AR, and RE were assigned by the "cutoff" method 28,29 because the chemical shifts cannot be accurately divided, in which their complex chemical composition and structure are similar to petroleum. Then, the relative contents of different types of hydrogen and carbon were calculated through area integration with the help of MestReNova.…”

“…2.2.8. 13 C-NMR Analysis of Group Components. Figure 9 shows the 13 C-NMR spectra of SA, AR, and RE.…”