We performed density functional theory (DFT) calculations using the WB97Xd functional with a dispersion correction term and the 6-31G(d,p) basis set to study the contributions of π–π stacking and hydrogen-bonding interactions to the aggregation of asphaltene model compounds containing a 2,2′-bipyridine moiety covalently bonded to one (monosubstituted) and two (disubstituted) aromatic hydrocarbon moieties (phenyl, naphthyl, anthracyl, phenanthryl, and pyrenyl) through ethylene tethers. In these compounds, the N atoms of the 2,2′-bipyridine moiety provide lone pairs for hydrogen bonding to water molecules present in solution. The aggregation strength of the homodimers of these model compounds is evaluated in terms of the aggregation energies, enthalpies, and ΔG298, as well as the π–π interaction distances. Geometry optimization and thermochemistry analysis results show that the homodimers of both mono- and disubstituted compounds are stable and have a negative ΔG298 of aggregation because of π–π stacking in...

Density Functional Theory Investigation of the Contributions of π–π Stacking and Hydrogen-Bonding Interactions to the Aggregation of Model Asphaltene Compounds

The structures of typical organic species in Jincheng No. 15 anthracite (J15A) were characterized by solid-state 13C nuclear magnetic resonance, X-ray photoelectron spectrometry, X-ray diffraction, and Fourier transform infrared spectrometry in combination with gas chromatography/mass spectrometry and electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry analyses of the resulting soluble organic species from ruthenium-ion-catalyzed oxidation (RICO) of J15A. The results show that the typical organic species in J15A are condensed aromatics, along with small amounts of methyl group as the dominant side chain on the condensed aromatic rings (CARs) and methylene linkage connecting the CARs. Every aromatic cluster contains five rings on average, and the substituted degree of each aromatic ring is very low. In addition, J15A is rich in peri-condensed aromatics but poor in cata-condensed aromatics and polyaryls. The oxygen functional groups in J15A include C–O and >C═O groups. Pyrrol...

Structural Characterization of Typical Organic Species in Jincheng No. 15 Anthracite

The methanol-insoluble portions from supercritical methanolysis of Shengli lignite (SL) and Huolinguole lignite (HL) were extracted with an isometric carbon disulfide/acetone mixed solvent under ultrasonic irradiation to afford extracts and extraction residues (ERs). The ERs were subjected to ruthenium-ion-catalyzed oxidation, and soluble portions were separated from the reaction mixture and esterified. The resulting products were analyzed with a gas chromatography/mass spectrometer and atmospheric solids analysis probe/time-of-flight mass spectrometer to reveal structural features of heavy species in the two lignites. The results show that the ER from SL is richer in highly condensed aromatic species than that from HL, while both ERs have the same carbon number range (C9–C24) of alkyl groups with the highest content at C15 on aromatic rings and the same distribution of alkylene bridges (C2–C20) connecting aromatic rings with a higher abundance of shorter linkages than that of longer linkages.

Structural Features of Extraction Residues from Supercritical Methanolysis of Two Chinese Lignites

Sequential oxidation of Jincheng No. 15 anthracite with aqueous sodium hypochlorite

Molecular Simulation for Petroleum Related Applications.- Molecular Structure and Association Behavior of Petroleum Asphaltenes.- Vanadium and Nickel Compounds in Heavy Petroleums.- Ruthenium Ion Catalyzed Oxidation for Petroleum Molecule Structural Features: A Review.- Molecular-level Composition and Reaction Modeling for Petroleum Complex System.

Structure and modeling of complex petroleum mixtures

The structure of coke from five spent residue hydrotreating catalysts was investigated based on ruthenium ion catalyzed oxidation reaction. The distribution of n-alkyl chains and bridges attached to aromatic carbon of coke on catalysts was quantified. Results showed the concentrations of n-alkyl chains and bridges in coke were declined with the increase of carbon number. The substituential group is methyl mainly, and it had no >C5 alkyl chains in coke. Various isomeric benzenepolycarboxylic acids from oxidated products were identified. Then the condensation mode of some aromatic structure was discussed. The precursor of coke affected the coke structure. Catalysts made coke dehydrogenate to form graphite type aromatic condensate. About 60% of coke was graphite type.

Structural Analysis of Coke on Used Catalysts during Residue Hydrotreating by Ruthenium Ion Catalyzed Oxidation Reaction

Structure of aromatics, resins, and asphaltenes in petroleum residue was undertaken by using ruthenium ion catalyzed oxidation. The distribution of alkyl side chains and bridges connected to aromatic rings was quantified, and the condensed type of aromatic rings was deduced. The structural changes of fractions in residue during hydrotreating were discussed. The results showed that fractions have abundant alkyl side chains (C1–C27), mainly n-alkyl side chains, attached to aromatic carbons, and polymethylene bridges connected to at least two aromatic ring systems are also present. The molar concentrations of these alkyl groups are declined as the increase of chain length. Cata-condensed, peri-condensed, and biphenyl-type aromatic unit structures coexist in fractions, while the proportion of biphenyl type structure is relatively small. The aromatic structure of aromatics is mostly cata-condensed, while for resins the proportion of cata-condensed and peri-condensed type aromatic structures is compara...

Z. Cheng

Papers

Structural Analysis of Coke on Used Catalysts during Residue Hydrotreating by Ruthenium Ion Catalyzed Oxidation Reaction

Structural Changes of Sub-fractions in Residue Hydrotreating Products by Ruthenium Catalyzed Oxidation