Characterization of Asphaltene Building Blocks by Cracking under Favorable Hydrogenation Conditions
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- 作者：Rosa I. Rueda-Vel谩squez ; Howard Freund ; Kuangnan Qian ; William N. Olmstead ; Murray R. Gray
- 刊名：Energy & Fuels
- 出版年：2013
- 出版时间：April 18, 2013
- 年：2013
- 卷：27
- 期：4
- 页码：1817-1829
- 全文大小：537K
- 年卷期：v.27,no.4(April 18, 2013)
- ISSN：1520-5029
文摘
The chemical building blocks that comprise petroleum asphaltene molecules were determined by thermal cracking of samples under conditions that minimized alterations to aromatic and cycloalkyl groups. Favorable hydrogenation conditions that used tetralin as a hydrogen-donor solvent and an iron-based catalyst allowed asphaltenes derived from different crude oils to yield approximately 50鈥?0 wt % distillates (<538 掳C fraction), with coke yields below 10 wt %, and reach conversions of the vacuum residue fraction between 65 and 75 wt %. Products in a wide range of boiling points, from naphtha to heavy material in the vacuum residue range, were observed by simulated distillation. Quantitative recovery of the cracked products, with mass balances above 96%, and characterization of the distillate fraction by gas chromatography鈥揻ield ionization鈥搕ime-of-flight high-resolution mass spectrometry (GC鈥揊I鈥揟OF HR MS) provided information on the abundance of building blocks, including saturates, 1鈥?-ring aromatics, 4+-ring aromatics, and nitrogen- and sulfide-containing molecules. Samples of asphaltenes from different geological basins exhibited a remarkable similarity in the yields of building blocks, with paraffins and 1鈥?-ring aromatics as the most abundant species. The diversity of molecules identified in the distillate products from the cracking of asphaltenes suggests a high degree of heterogeneity and complexity of asphaltene molecules, built up by smaller fragments attached to each other by bridges. The sum of material remaining in the vacuum residue fraction and the yield of coke were in the range of 35鈥?5% and represent the maximum amount of large aromatic clusters present in asphaltenes that could not be converted to distillates or gases under the cracking conditions used in this study.