毕业时间：2017年6月（硕士）

毕业去向：苏丹

导师：史权 教授 

学科专业：化学工程与技术

研究方向：重质油加工

 

学位论文题目 Title

加氢处理过程中难脱除硫化物的表征：不同地质来源原油中的分子表征与分布

Characterization of Refractory Sulfidic Compounds in the Hydrotreating Process: Molecular Characterization and Distribution in Crude Oils with Various Geological Origins

 

论文摘要 Abstract

Refractory sulfur compounds in crude oil represent one of the most persistent challenges to the modern petroleum-refining industry. Their incomplete removal during hydrodesulfurization (HDS) is directly responsible for elevated SOₓ emissions, acid deposition, catalyst poisoning in downstream units, and non-compliance with ultra-low-sulfur (< 10 ppm) specifications imposed by Euro VI, China VI-B, and the U.S. Tier-3 fuel standards. Among the refractory sulfur family, alkyl-substituted dibenzothiophenes (particularly 4-MDBT and 4,6-DMDBT) and their partially hydrogenated analogues — hexahydrodibenzothiophenes (H6DBT, also termed HHDBT) — are the most difficult to desulfurize because of severe steric shielding of the sulfur atom.

In this work, a selective methylation/demethylation separation protocol was developed and applied to a heavy crude-oil sample recovered from the ultra-deep Ha9 discovery well of the Tarim Basin (Xinjiang, China; 6,598–6,710 m). Sulfidic and thiophenic sulfur compounds were first converted into polar methyl-sulfonium tetrafluoroborate salts by reaction with methyl iodide (CH₃I) in the presence of silver tetrafluoroborate (AgBF₄) in dichloromethane. The salts were isolated by silica-gel column chromatography, then selectively demethylated using indazole and 4-dimethylaminopyridine (4-DMAP) to yield two distinct fractions: (i) a thiophenic fraction and (ii) a sulfidic fraction. Both fractions were subsequently analyzed by gas chromatography-mass spectrometry (GC-MS) with a UV detector operating over the retention-time window 0–47 min.

Chromatographic profiles revealed an intense and structurally isolated peak in the sulfidic fraction, unambiguously assigned to hexahydrodibenzothiophene (H6DBT) by comparison with published mass spectra and retention indices (Wang et al., 2015; Lu et al., 2014; Zhang et al., 2023). The compound was virtually absent from the parent thiophenic fraction, confirming that the geometric non-planarity introduced by the cis-fused cyclohexane ring renders H6DBT sulfidic in reactivity even though it retains the aromatic thiophene skeleton.

Building on the recent geochemical evidence of Wang et al. (2015) and the 2024–2026 FT-ICR MS surveys of Tarim ultra-deep oils (Zhu et al., 2025; Oliveira et al., 2025), it is proposed that H6DBT is not a diagenetic artefact of dibenzothiophene hydrogenation but a genuine biomarker derived from the sulfurization of retinol-type C₂₀ isoprenoid precursors under anaerobic conditions in ultra-deep reservoirs (6,000–7,500 m). On this basis a new trivial name — “RETINOLTHIOPHENE” — is proposed to reflect its biological origin and geochemical significance, distinguishing it from thermal-cracking hydrogenation products of planar DBT.

The thesis also reviews the state-of-the-art in HDS catalyst design (2020–2026), including next-generation NiMoS/Al₂O₃-TiO₂, Co-promoted MoS₂ quantum-dot catalysts, single-atom catalysts, and ionic-liquid-assisted oxidative desulfurization, and shows why steric hindrance around the sulfur in cis-H6DBT still limits conversion below 30 % at industrial LHSV. The findings provide a molecular target that any future ultra-deep HDS catalyst must be able to activate.

Keywords: Refractory Sulfur; Hydrodesulfurization (HDS); Methylation/Demethylation; Hexahydrodibenzothiophene (H6DBT); Retinolthiophene; Tarim Basin Ha9 Oil; GC-MS; Sulfur Biomarker; Heavy-Oil Processing.

发表学术论文 Publications

1. [1]

   Wu J, Hamid AA, Zhang W, Li S, Zhang Y, Liao Y, Shi Q. The occurrence and geochemical origin of 9-alkyl HDBTs substituted by long isoprenoid alkyl chains in crude oil. Org Geochem 2024;188
   https://doi.org/10.1016/j.orggeochem.2023.104721