Bulk and molecular composition variations of gold-tube pyrolysates from severely biodegraded Athabasca bitumen

• 来源期刊: 石油科学（英文版）
• 年，卷（期）: 2020,（6）
• 页码范围: 1527-1539
• 页数: 13页
• 语种: 英文

摘要

Gold-tube pyrolysis experiments were performed on two Athabasca oil sand bitumens at 300 ℃ to 525 ℃ with 2 ℃/h rate and 25 ℃ step under 50 MPa.Pyrolysis temperature of 425 ℃ is critical for weight loss of bulk bitumen and hydro-carbon generation and destruction.Polar compounds are the main source of saturated and aromatic hydrocarbon,gas and coke fractions.Molecular compositions in pyrolyzates vary systematically with increasing pyrolysis temperatures.High molecular weight n-alkanes(C26+)are gradually destructed during pyrolysis due to thermal cracking.Moderate molecular weight n-alkanes(C21-C25)show the highest thermal stability in designed pyrolysis temperatures.The loss of low molecu-lar weight n-alkanes(C20-)might be caused by volatilization during pyrolysis,which may alter commonly used molecular parameters such as Jjn-C20-/2n-C21+,Pr/n-C17 and Ph/n-C18.Aromatic hydrocarbons were generated from 300 to 425 °C,then condensation and dealkylation have been initiated at 425 ℃ as evidenced by decreased summed alkylnaphthalenes to alkylphenanthrenes ratios and increased unsubstituted aromatics to substituted homologs ratios in higher temperatures.The occurrence of anthracene and benz[a]anthracene in pyrolysates indicates pyrogenic origin,while fluoranthene shows unex-pected behaviors during pyrolysis.Ratios derived from them are not always reliable for pyrogenic source input diagnosis in environmental samples.