Influence of Different Compound Classes on the Formation of Sediments in Fossil Fuels During Aging

Abstract

The formation of sediments is a serious instability problem in the storage of fossil fuels. Reactions that lead to sediment formation can be linked to the oxidation of certain fuel components that contain oxygen, nitrogen, or sulfur. To study the oxidation reactions that occur during aging of fuels, we doped a model fuel with several representatives of such compound types. The compounds used were 2,6-dimethylphenol, 2-naphthol, 2,5-dimethylpyrrole, 2-methylindole, dibenzothiophene, and pentamethylene sulfide. After an artificial aging of the samples according to the DGMK-714 protocol, the formed sediments were analyzed by electrospray ionization mass spectrometry (Orbitrap, ESI-MS), elemental analysis, infrared measurements, and mass analysis. Mass spectrometry indicated monomeric and dimeric oxidation products with two to nine oxygen atoms as well as products with different hydrocarbon structures (different C/H ratios) from 2,6-dimethylphenol. 2-Naphthol led to oligomers consisting of up to six monomer units and showing different degrees of oxidation. The first ever recorded cross-coupling between 2,6-dimethylphenol and 2-methylindole and between 2-naphthol and 2,5-dimethylpyrrole is also shown. In general, the tested nitrogen compounds and especially the phenols tended to form oxidized oligomers, whereas the sulfur compounds led to sulfoxides and sulfones.

Adsorptive Removal of Indole and Quinoline from Model Fuel over Various UiO-66s: Quantitative Contributions of H-Bonding and Acid–Base Interactions to Adsorption

“…However, before the removal of SCCs, NCCs present in fuels should be eliminated since they reduce the activity of HDS catalysts and hinder the catalytic process itself . Indole (IND) and quinoline (QUI), and their derivatives are the most common NCCs that exist naturally in fossil fuels . NCCs can be classified into two groups: basic and neutral or nonbasic.…”

“…12 Indole (IND) and quinoline (QUI), and their derivatives are the most common NCCs that exist naturally in fossil fuels. 13 NCCs can be classified into two groups: basic and neutral or nonbasic. IND and its derivatives are neutral, whereas QUIs are basic in nature.…”

Examination of Two-Dimensional Gas Chromatography with a Nitrogen Chemiluminescence Detector to Facilitate Quantitation and Characterization of Nitrogen-Containing Compounds in Petroleum-Derived Fuels

“…11 NCCs in fuels promote corrosion, 12 adversely affect fuel thermal and storage stability 13−16 and contribute to sediment and gum formation. 17,18 Sediments and gums are major concerns for fuel systems as they plug fuel and engine filters and burner nozzles, which hinders or obstructs fuel flow thereby attenuating engine performance. 19 Past studies evaluated how different classes of NCCs influence the propensity to contribute to stability-related issues.…”

“…11 However, such simplified classifications for NCCs in fuels may not be as germane, as both basic and nonbasic NCCs were shown to contribute to fuel degradation. 17,21,22 Additionally, the production of two fractions (i.e., basic and nonbasic) may not guarantee complete separation of different classes of NCCs within the same fraction when using GCxGC. For example, Adam et al 29 demonstrated that anilines and quinolines in the basic fraction coeluted in the GCxGC chromatogram, which complicated classification and quantitation of NCCs in diesel samples.…”

“…17 Sil MS, 30 m × 250 μm × 0.25 μm, Restek, Bellefonte, PA) and a 2 m secondary nonpolar column (Rxi-1 MS, 2.1 m × 100 μm × 0.1 μm Restek, Bellefonte, PA). The helium carrier gas flow rate was set to 1.6…”