Hydroaromatic Species Research Articles

The Role of Hydroaromatic Species in the Oxidation of Petroleum Bitumens

Model dihydroaromatic compounds (0.021 M and 0.123 M) and Safaniya petroleum bitumen (ca. 0.021 M) in toluene and Decalin solution at 50.0 °C were oxidized with air for up to 500 h in the dark. The rate of oxygen uptake was measured by gas chromatography using a column packed with molecular sieve 5A at 70 °C. The model compounds showed a slow linear rate of oxidation with an induction period apparent in some cases. In contrast the bitumen showed no induction period and the typical rapid initial rate of reaction becoming linear at longer times (>100 h) was observed. Oxidation of the most reactive of the model compounds (9,10-dihydroanthracene) was inhibited by 2,4-di-tert-butyl-4-methylphenol whereas the reaction of bitumen was unaffected. Bitumen and DHA did not act synergistically to increase the overall rate of oxygen uptake (compared to the sum of the individual reactions) when co-oxidized in toluene. Bitumen (4 g, ca. 0.0064 mols) hydrogenation with o-chloranil (0.203 g, 0.00082 mol) in refluxing tolu...

Reexamination of the RICO Method

Information about bridge structure and functionalities has been considered to be crucial in estimating the reactivity of coals, and the purpose of this study is to improve the validity of the RICO technique in the determination of aliphatic bridges and functional groups using a Japanese Taiheiyo coal. It was found that room temperature, which had been commonly employed previously, is insufficient for efficient oxidation kinetics and higher temperature such as 40 °C increased the oxidation kinetics 2-fold. Candidates for the remarkable amounts of resolved aliphatic polycarboxylic acid products are thought to be the corresponding polyaryl-substituted aliphatic cross-linkages and various hydroaromatic species. Remarkable amounts of polymeric aliphatic fraction were also formed after RICO. Much higher amounts of benzenepolycarboxylic acids were recovered, and significant improvement of carbon mass balance was achieved contrary to previous reports.

Comparison of hydrogen transfer from cyclic olefins and hydroaromatic donors under thermal and catalytic liquefaction conditions

A new class of compounds is being investigated for their ability to donate hydrogen during coal liquefaction. The compounds, known as cyclic olefins, are hydroaromatic species without an aromatic ring. These compounds are extremely reactive at coal liquefaction conditions, readily forming other partially saturated compounds and aromatics. This investigation demonstrates the effectiveness of these compounds for coal conversion and liquefaction products. 1,4,5,8-Tetrahydronaphthalene, also known as isotetralin, and 1,4,5,8,9,10-hexahydroanthracene are the two cyclic olefins employed in this study. Their hydrogen-donating ability, as reflected by the amount of coal converted to tetrahydrofuran solubles, is compared to that of their conventional hydroaromatic analogues, tetralin, dihydroanthracene, and octahydroanthracene, at equivalent donable hydrogen levels

COPROCESSING OF PITTSBURGH NO. 8 COAL USING HYDROGEN DONORS AND REDUCED RESIDS

ABSTRACT Pittsburgh No. 8 coal was coprocessed with five different resids to establish the effect of these resids on coal conversion at 380°C in a hydrogen atmosphere. The resids with the highest asphaltene content yielded the most conversion. The addition of hydrogen donor species like the cyclic olefins, 1,4,5,8-tetrahydronaphthalene(isotetralin)and 1,4,5,8,9,10-hexahydroanthracene, and hydroaromatic species, 9,10-dihydroanihracene, 1,2,3,4,5,6,7,8-octahydro-anlhracene, and tetralin, increased the amount of coal conversion obtained in the coprocessing systems regardless of the resid used as solvent. Dihydroanthracene and hexahydroanthracene had the greatest effect on coal conversion while both octahydroanthracene and isotetralin showed positive but lesser effects on coal conversion. Reduction of three resids with the Birch reduction method yielded resids with a greater hydrogen donor capacity which resulted in higher coal conversion than the parent resid and comparable coal conversion to that obtained w...

Chemistry and reactivity of cyclic olefins as donors in coal liquefaction

A new set of hydrogen-donor compounds, cyclic olefins, has been evaluated to determine their effectiveness as hydrogen donors to coal. These cyclic olefins are hydroaromatic species that do not contain aromatic rings. The reactivity and hydrogen donability of these cyclic olefins have been compared to those of conventional hydroaromatics. The cyclic olefins under study are 1,4,5,8-tetrahydronaphthalene,also known as isotetralin, and 1,4,5,8,9,10-hexahydroanthracene. Cyclic olefins are much more reactive, releasing more hydrogen than their conventional hydroaromatic analogues, both with and without coal

Carbonization of anthracene in a batch reactor

The coking of liquid anthracene in a batch tubular reactor was followed by measuring the formation of pyridine insolubles and the disappearance of anthracene as a function of time over the temperature range 465–525°C. Conditions, that can affect coking behavior and rates, like partition of the feed between liquid and vapor, agitation of the reactor, and whether the gas pressure in the reactor is autogeneous or imposed are considered. Carbonization primarily involves hydrogen-transfer reactions and condensation (polymerization) of free radicals into larger molecular weight species. Cleavage (cracking) of hydroaromatic species, giving smaller liquid and gas phase molecules, is at a minimum under the conditions used in this study.

Reaction pathways of model coprocessing systems using molybdenum naphthenate and excess sulfur

The activity and selectivity of catalysts generated in situ from molybdenum naphthenate and excess sulfur for reactions occurring in coal-oil reactions have been examined. The reaction pathways for species representative of those present in coal and petroleum residuum are presented. The MoS 2 catalyst generated in situ promotes partial saturation of the multiring aromatic to hydroaromatic species but does not promote further saturation of the hydroaromatic or of single-ring alkyl-substituted aromatics. Heteroatom removal with this in situ generated MoS 2 catalyst follows two simultaneous reaction pathways: one for heteroatom removal prior to saturation of the aromatic rings producing alkyl-substituted single-ring aromatics and the other for heteroatom removal after saturation of the aromatic rings producing primarily alkyl-substituted cyclic hydrocarbons

Donor solvent interactions during coal liquefaction

Two UK bituminous coals (Cresswell and Point of Ayr) were liquefied using ternary solvents composed of 9,10-dihydroanthracene, 1-methylnaphthalene and a variety of aromatic and heteroatomic compounds. Coal conversion yields were measured in terms of THF- and quinoline-soluble material, following reactions in a stirred batch autoclave under standard conditions of 1 h at 400 °C, and with normalized amounts of hydroaromatic components present as solvent. Enhancement of coal conversion yields was observed for two aromatic compounds (fluorene and pyrene) and for 1- and 2-naphthol. Different mechanisms were established for the synergistic effects of fluorene and pyrene. Antisynergism was observed while using a secondary alcohol, 9-fluorenol, as a solvent component. In binary solvents composed of a hydroaromatic species and 1-methylnaphthalene, 9,10-dihydroanthracene was found to be a more efficient hydrogen donor than tetralin and the efficiency was observed to vary monotonically with the donatable hydrogen concentration of the solvent.

Chemical changes and ignition quality improvement resulting from hydrotreating light cycle oil

A light cycle oil (LCO) product from a fluidized catalytic cracker unit was hydrotreated under a wide range of severities and the resulting chemical changes were monitored using h.p.l.c., 13C n.m.r. spectroscopy, elemental analysis and density measurement. Aromatic hydrogenation occurred under all conditions, the highly substituted molecules being the most difficult to hydrogenate. At the low severities typically used in refinery desulphurization units, the main reaction was partial hydrogenation of two-ring and polynuclear aromatics, leading to the formation of hydroaromatic species. Cetane number increases of ⩽ 7 resulted. At higher severities (which are required when refining coal syncrudes), mono-aromatic hydrogenation occurred and resulted in the formation of cycloparaffins. For a hydrogen partial pressure of 20 MPa, cetane number increases of up to 31 were obtained. The amount of aromatic hydrogenation required to upgrade the LCO to specification-quality diesel fuel was determined.

Still more on the reaction of the intercalation compound C 8K with water

The reaction of C 8K made from polycrystalline Ultracarbon with D 2O leads to a solid phase product containing both potassium and water. The absence of quadrupole splitting in the 2D NMR of the product argues against the presence of crystalline water of hydration, as in potassium hydroxide monohydrate. X-ray diffraction and electron spin resonance show the carbon skeleton to be inequivalent to the initial graphite. Hydrogen evolution in the reductive protonation of the dianion of perylene is shown to arise from an unstable intermediate hydroaromatic species.

Petroleum heavy oil mixtures as a source of hydrogen in the liquefaction of Cerrejon coal

Petroleum heavy oil and anthracene oil were used as hydrogen donor solvents in a coal liquefaction test. A positive synergistic effect was obtained when mixed (petroleum heavy oil; anthracene oil) solvent was employed. The temperature of maximum conversion was also lower for this mixed solvent than for any of the solvents alone. It is shown from the 1 H n.m.r. spectral data that petroleum heavy oil acts as a hydrogen donor to anthracene oil resulting in hydroaromatic derivatives. These hydroaromatic species donate hydrogen to the coal fragments. The 1 H n.m.r. spectral data allow monitoring of the temperature at which the petroleum heavy oils have maximum donor capacity and consequently the temperature for coal liquefaction in this process.

Determination of transferrable hydrogen in coal liquids by mass spectrometry

Two low-resolution mass spectral (LRMS) group type analyses have been calibrated to quantify transferable hydrogen and to characterise more accurately the aromatic and hydroaromatic species in coal liquids. The analysis for light coal liquids (50-300 C) reports 20 aromatic and hydroaromatic types including phenols and dihydroxybenzenes, while the analysis for heavy coal liquids (300-500 C) reports 30 aromatic and hydroaromatic species. The LRMS transferable hydrogen values were shown to be in good agreement with /sup 13/C NMR values for a series of coal liquid distillates and process oils.

Estimation of the concentration of donatable hydrogen in a coal solvent by n.m.r.

1H and 13C nuclear magnetic resonance (n.m.r.) spectroscopies have been used to study the changes in composition of a hydrogenated anthracene oil solvent that occur during extraction of a UK bituminous coal. It has been shown that the principal hydrogen donor groups in the solvent are hydroaromatic and naphthenic rings in hydroaromatic species. Good agreement was achieved between the concentration of donatable hydrogen estimated from n.m.r., and the amount of hydrogen transferred from the solvent during exhaustive extraction.

Chemical characterization of coal. 3. Qualitative and quantitative aspects of the reductive methylation of coal

The treatment of coal with solvated electrons (formed as a blue solution by treating potassium with the dimethyl ether of ethyleneglycol) followed by solvolysis of the polyanionic coal with dimethylsulphate allows coal derivatives to be prepared, 85 wt% (daf) of which can be extracted with pyridine. Detailed investigations of these products, and of analogous deuterium-labelled derivatives, show that an average of 7 methyl groups per 100 C atoms have been introduced in a single treatment. This value can be increased by a second treatment, l.r. structure-element analysis shows, in addition, that 35% of the hydrogen so introduced forms hydroaromatic species and takes part in the degradation of aromatic structures. The site of the reaction is studied by comparing the results from the deuteromethylation of coal and of model compounds: it is suggested that the marked increase in extractability results from the cleavage of aliphatic bridges of the type ArCH 2CH 2Ar' giving ethyl-substituted aromatics and related products. A method is described which determines increments from quantitative i.r. measurements for model compounds and allows a rapid determination of the Cl 3-content of a deuterated coal.

In-vitro assay for mutagenic activity and gas chromatographic-mass spectral analysis of coal liquefaction material and the products resulting from its hydrogenation

Employing assays for microbial mutagenesis activity together with solvent fractionation and gas chromatographic-mass spectral analysis, coal liquefaction material was compared to its catalytically hydrogenated products with regard to biological activity and chemical composition. The mutagenic activity of the moderate and severly hydrogenated products was substantially reduced compared to that of the feedstock. In contrast to the essentially aromatic nature of the principal components in the coal oil feedstock, the hydrogenated products were shown to contain mainly hydroaromatic species with a significant decrease in the fraction of basic and tar components as obtained by our acid-base solvent separation procedure. Subfractions of the basic and tar components obtained from the feedstock were shown to contain primary aromatic amines, the concentrations of which were essentially in direct proportion to the observed microbial mutagenic activity. No primary aromatic amines were detected in the hydrogenated products. Hydrotreating appears to produce a coalderived liquid with far less mutagenic activity than the untreated coal liquefaction material.