Crude aromatics content

Debutanized gasoline cuts from Arabian Light crude. Reid Vapor Pressure as a function of yield, weight %. Aromatics content as a function of yield, volume %. 

The crude ketal from the Birch reduction is dissolved in a mixture of 700 ml ethyl acetate, 1260 ml absolute ethanol and 31.5 ml water. To this solution is added 198 ml of 0.01 Mp-toluenesulfonic acid in absolute ethanol. (Methanol cannot be substituted for the ethanol nor can denatured ethanol containing methanol be used. In the presence of methanol, the diethyl ketal forms the mixed methyl ethyl ketal at C-17 and this mixed ketal hydrolyzes at a much slower rate than does the diethyl ketal.) The mixture is stirred at room temperature under nitrogen for 10 min and 56 ml of 10% potassium bicarbonate solution is added to neutralize the toluenesulfonic acid. The organic solvents are removed in a rotary vacuum evaporator and water is added as the organic solvents distill. When all of the organic solvents have been distilled, the granular precipitate of 1,4-dihydroestrone 3- methyl ether is collected on a filter and washed well with cold water. The solid is sucked dry and is dissolved in 800 ml of methyl ethyl ketone. To this solution is added 1600 ml of 1 1 methanol-water mixture and the resulting mixture is cooled in an ice bath for 1 hr. The solid is collected, rinsed with cold methanol-water (1 1), air-dried, and finally dried in a vacuum oven at 60° yield, 71.5 g (81 % based on estrone methyl ether actually carried into the Birch reduction as the ketal) mp 139-141°, reported mp 141-141.5°. The material has an enol ether assay of 99%, a residual aromatics content of 0.6% and a 19-norandrost-5(10)-ene-3,17-dione content of 0.5% (from hydrolysis of the 3-enol ether). It contains less than 0.1 % of 17-ol and only a trace of ketal formed by addition of ethanol to the 3-enol ether. 

Atmospheric gas oil has a relatively lower density and sulfur content than vacuum gas oil produced from the same crude. The aromatic content of gas oils varies appreciably, depending mainly on the crude type and the process to which it has been subjected. For example, the aromatic content is approximately 10% for light gas oil and may reach up to 50% for vacuum and cracked gas oil. Table 2-7 is a typical analysis of atmospheric and vacuum gas oils. ... 

Gasoline varies widely in composition, and even those with the same octane number may be quite different. The variation in aromatics content as well as the variation in the content of normal paraffins, branched paraffins, cyclopentane derivatives, and cyclohexane derivatives all involve characteristics of any one individual crude oil and influence the octane number of a gasoline. 

The amount of benzene produced in a reformer will depend on the composition of the feed. Every crude oil has naphtha with different PNA (paraffin, naphthene, aromatics) content. In commercial naphtha trading, the PNA content is often an important specification. High naphthene and aromatic content would indicate a good reformer feed. High paraffin content would indicate a good olefin plant feed. 

This most widely used black pigment is also in the top 50 chemicals. About 4.0 billion lb of carbon black were made in 2001. Commercial value was 1.4 billion at 35C/lb, but 93% of this is used for reinforcement of elastomers. Only 7% is used in paints and inks. Carbon black is made by the partial oxidation of residual hydrocarbons from crude oil. See Chapter 6, Section 7.2. The hydrocarbons are usually the heavy by-product residues from petroleum cracking, ideally high in aromatic content and low in sulfur and ash, bp around 260°C. 

In this manner the predicted curve 6f Figure 7, showing the effect of varying petrolene viscosity at constant level of penetration, was obtained. Other asphalts were prepared and analyzed for the above variables. The experimental points were placed on Figure 7. Agreement between the predicted curves and the experimental points is seen to be satisfactory. Figure 7 illustrates that in this penetration range, gel-type asphalts are obtained only from crudes of low aromatic content at low petrolene viscosities. As the petrolene viscosity is increased, asphalts from all crudes tend toward the viscous type. At lower penetrations, the curves are shifted upward, so that hard asphalts from the more aromatic crudes have rather complex flow properties. 

Liquid chromatography (also called adsorption chromatography) has helped to characterize the group composition of crude oils and hydrocarbon products since the beginning of this century. The type and relative amount of certain hydrocarbon classes in the matrix can have a profound effect on the quality and performance of the hydrocarbon product. The fluorescent indicator adsorption (FIA) method (ASTM D-1319) has been used to measure the paraffinic, olefinic, and aromatic content of gasoline, jet fuel, and liquid products in general (Suatoni and Garber, 1975 Miller et al., 1983 Norris and Rawdon, 1984). 

The aniline point of crude oil is the temperature at which equal parts of aniline and the oil are completely miscible. For oils of a given type, the aniline point increases slightly with molecular weight but increases markedly with paraffinic character and may therefore be used to obtain an approximate estimation of aromatics content. Aniline point determinations are only infrequently applied to heavy oils and residua since their very character, and the other evaluation methods outlined here, indicates them to be complex with high proportions of ring systems (aromatic constituents and naphthene constituents). 

Eckart and co-workers have published a series of papers on laboratory studies of biodesulfurization of petroleum and petroleum fractions. The ability of various aerobic mixed cultures to desulfurize Romashkino crude oil (1.69 wt.% S) was addressed by Eckart et al. (21). After 5 days of incubation at 30°C in sulfur-free mineral medium with oil as sole source of carbon and sulfur, approximately 55% of the total sulfur was recovered in the aqueous phase from two of the most active cultures. In another study, gas oil (1.2 to 2 wt.% S), vacuum distillates (1.8 to 2 wt.% S) and fuel oil (up to 4 wt.% S) were used as sole carbon and sulfur sources for the oil-degrading microorganisms (36). The addition of an emulsifying agent was required to enhance desulfurization. Sulfur removals of up to 20% from the gas oil, 5% from the vacuum distillates, and 25% from the fuel oil were observed after 5 to 7 days of incubation. In a later study (37). approximately 30% of the sulfur was removed from fuel-D-oil by a mixed population of bacteria. The removal of benzothiophene, dibenzothiophene and naphthobenzothiophene was shown by high resolution MS analysis. Hydrocarbon degradation was observed in each of these studies. For example, in the latter study with fuel-D-oil, the decreases in the n-alkane and aromatic content were 59% and 14%, respectively. 

The aromatic content of the oil was 33 per cent (10) as measured by carbon-13 nmr. Crude distillation at atmospheric pressure yielded a major fraction (42 per cent) which boiled in the range 190-350°C and unlike the crude product was completely miscible with diesel fuel. A duplicate of this seven run series was carried out and it yielded very similar results. Results for shorter series in which different amounts of catalyst were added will be reported elsewhere (11). 

These and many other aromatics have been isolated from petroleum fractions. The aromatic content of crude oils can vary widely, but an aromatic content of a third or more of the total, as has been noted for some Borneo crudes, is not unusual [5]. The density (or °API) of a crude oil is an indicator of the aromatic content since the high C H ratio of aromatic components tends to make these the most dense constituents present. This is particularly true with polynuclear aromatic constituents since each additional ring further reduces the hydrogen count by two, increasing the already high C H ratio and therefore also the density. 

The aniline point (or mixed aniline point) (ASTM D-611, IP 2) has been used for the characterization of crude oil, although it is more applicable to pure hydrocarbons and in their mixtures and is used to estimate the aromatic content of mixtures. Aromatics exhibit the lowest aniline points and paraffins the highest aniline points. Cycloparaffins and olefins exhibit values between these two extremes. In any hydrocarbon homologous series the aniline point increases with increasing molecular weight. 

Naphthenics are made from a more limited range of crude oils than paraffinics, and in smaller quantities, at a restricted number of refineries. Important characteristics of naphthenic base oils are their naturally low pour points, because they are wax-free, and excellent solvency powers. Their viscosity/temperature characteristics are inferior to paraffinics, i.e. they have low/medium VI, but they are used in a wide range of applications where this is not a problem. Since naphthenic crudes are free of wax, no de-waxing step is needed but solvent extraction or hydrotreatment is often used now to reduce aromatic content and especially to remove polycyclic aromatics which may present a health hazard in untreated oils. The main producers of naphthenics are in North and South America because most of the world s supply of naphthenic lubricant crudes are found there. 

The oil originally used in oil-based drilling fluids was either crude or diesel oil. These oils have been largely replaced by refined mineral oils with aromatic contents below about 0.25 wt% (53). Alternative oil phases that have recently been introduced are poly(alphaolefins) (54) and esters derived from vegetable oils (55). These and other synthetic oils have been introduced in response to environmental pressures on the disposal of waste oil. 

Bitepazh s paper. The catalytic activity was checked by two reactions, namely, cracking a crude oil with a boiling range of 210-300°, and re-forming of a naphtha fraction (aromatic content 0%). 

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