Characteristics Of Oil Shale Pyrolysis With Thermal Bitumen As The Pyrolysis Intermediate

In this paper,the pyrolysis intermediate of Longkou oil shale thermal bitumen was prepared.The effects of pyrolysis temperature on the structure of thermal bitumen as the pyrolysis intermediate of Longkou oil shale are investigated through electron paramagnetic resonance spectroscopy?EPR?,Fourier transform infrared?FTIR?spectroscopy,nuclear magnetic resonance?NMR?spectroscopy,gas chromatography–mass spectrometry?GC–MS?,and X-ray photoelectron spectroscopy?XPS?.The results showed that over 83%compounds of thermal bitumen was aliphatic compounds.The average molecular chain length was 10-14.With the increasing temperature,the content of aliphatic compounds and degree of branching decreased.The oxy-compounds was mainly constituted of O=C-O,and with the increase of pyrolysis temperature,C-O of carboxylic acid groups will break first,then the generated CO₂ escaped from thermal bitumen.The C=O between 330?to 370?carbon oxygen contents was significantly reduced,CO₂ was generated mainly at this temperature range.Nitrogen compounds were mainly composed of pyrrole compounds,about 50%of the total nitrogen compounds.The sulfide in thermal bitumen was mainly composed of thiophene and sulfones sulfur compounds,accounts for about 60%of the total sulfur.thiophene compounds was generated with pyrolysis process and mianly accumulate in thermal bitumen.The strcture of Longkou and Estonia oil shale kerogen and its pyrolysiates,thermal bitumen,retorting gas,shale oil and semicoke were analyzed.The gaussview was carried to simulate the pyrolysis characteristics of oil shale.The results found that when the pyrolysis temperature below 340?,the retorting gas was mainly composed of CO and CO₂.The C2-5 organic gas were mainly generate between 360?⁴40?.When the temperature was higher than 460?,the gas generation was nearly no more generated.The aliphatic compounds was shown poor thermal stability wthich was easily decomposed through thermal bitumen and remained in the shale oil.The aromatic compounds in the shale oil and semicoke was significantly higher than that of thermal bitumen and kerogen,which indicated that aromatic compounds were came from aromatization reaction of aliphatic compounds.PY-GC-MS results showed that Longkou shale kerogen were mainly composed of alkanes and olefins compounds accounted for 79.34%of total peak area,and 82.47%in Estonia kerogen.The aromatic compounds of Longkou oil shale kerogen was 4.78%and 5.32%of Estonia oil shale kerogen,the polycyclic aromatic hydrocarbons were not detected.Heteroatomic compounds content was mainly composed of oxy-compounds,such as esters,ketones compounds.The analog analysis C₂₁ n-alkanes results indicated that the bond energy of methyl carbon was 389.32 kJ/mol,and the decomposition energy of ether compounds was about 356.77 kJ/mol which was less than that of end methyl.Indicated that the oxygen containing compounds,such as ethers compounds was easier to decompose at low temperature than alkanes and alkenes compounds.The generation of benzene ring needed more energy.The hydrogen generated generally from the aromatization of aliphatic compounds.