Alostad Latifa K, Palacio Lozano Diana Catalina, Gannon Benedict, Downham Rory P, Jones Hugh E, Barrow Mark P
Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom.
Molecular Analytical Sciences Centre for Doctoral Training, University of Warwick, Coventry CV4 7AL, United Kingdom.
Energy Fuels. 2022 Aug 18;36(16):8663-8673. doi: 10.1021/acs.energyfuels.2c01168. Epub 2022 Aug 1.
The composition of asphaltenes is of interest due to the challenges they pose for industry and their high complexity, encompassing a range of heteroatom contents, molecular weights, double bond equivalents (DBEs), and structural motifs. They are well-known for aggregating above critical concentrations, hindering the upstream and downstream processes. Asphaltenes are defined by solubility, as they are insoluble in light paraffins such as -heptane and soluble in aromatic solvents such as toluene. Today, enormous efforts are being invested into the characterization of asphaltenes to shed light into their structural profiles to benefit the petroleum industry and environmental sustainability. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) provides molecular level analysis with unparalleled mass resolving power and mass accuracy, which is vital for the characterization of inherently complex crude oils and their asphaltene fractions. The aim of this research is to elucidate and compare the compositional profiles of asphaltene fractions of two petroleum samples, fractioned through two approaches: using -heptane, as is typical practice, and -nonane, for the purpose of testing extraction using higher molecular weight alkanes. The results highlight that the choice of solvents does indeed influence the accessibility of different species and therefore changes the observed molecular profiles of the extracted asphaltenes. -Heptane afforded broader contributions of different heteroatomic classes and greater carbon number ranges of the observed components; the DBE distribution vs carbon number profiles were different, where the extracts produced using -nonane displayed a greater prevalence of lower DBE species.
由于沥青质给工业带来的挑战以及其高度复杂性，包括一系列杂原子含量、分子量、双键当量（DBE）和结构基序，其组成备受关注。它们以在临界浓度以上聚集而闻名，这会阻碍上游和下游工艺。沥青质是根据溶解度来定义的，因为它们不溶于轻质石蜡如庚烷，而溶于芳香族溶剂如甲苯。如今，人们投入了巨大努力来表征沥青质，以揭示其结构特征，从而使石油工业和环境可持续性受益。傅里叶变换离子回旋共振质谱（FT-ICR MS）提供了具有无与伦比的质量分辨能力和质量准确性的分子水平分析，这对于表征本质上复杂的原油及其沥青质馏分至关重要。本研究的目的是阐明并比较两个石油样品的沥青质馏分的组成特征，这两个样品通过两种方法进行分馏：按照典型做法使用庚烷，以及使用壬烷，目的是测试使用更高分子量烷烃进行萃取的效果。结果表明，溶剂的选择确实会影响不同物种的可及性，因此会改变所观察到的萃取沥青质的分子特征。庚烷能使不同杂原子类别的贡献更广泛，且所观察到的组分的碳数范围更大；DBE分布与碳数的关系曲线不同，使用壬烷萃取得到的提取物中低DBE物种的占比更高。
