Of aromatic fraction

Figure 12.22 SFC-GC analysis of aromatic fraction of a gasoline fuel, (a) SFC trace (b) GC ttace of the aromatic cut. SFC conditions four columns (4.6 mm i.d.) in series (silica, silver-loaded silica, cation-exchange silica, amino-silica) 50 °C 2850 psi CO2 mobile phase at 2.5 niL/min FID detection. GC conditions methyl silicone column (50 m X 0.2 mm i.d.) injector split ratio, 80 1 injector temperature, 250 °C earner gas helium temperature programmed, — 50 °C (8 min) to 320 °C at a rate of 5 °C/min FID detection. Reprinted from Journal of Liquid Chromatography, 5, P. A. Peaden and M. L. Lee, Supercritical fluid chromatography methods and principles , pp. 179-221, 1987, by courtesy of Marcel Dekker Inc.

Since the removal of aromatics from fuel oils lowered toxicity, attention was directed to other highly aromatic fractions. Avon weed killer, a very aromatic material, had proved toxic and it was soon proved that many other aromatic fractions were effective. Unfortunately, most of the old sources of aromatic fractions were soon exhausted, but tests proved that the bottoms from the catalytic cracked stocks were similarly toxic. Shell No. 20, Standard No. 2, and a host of other toxic weed oils soon came onto the market, and the demands on Diesel and smudge-pot oils were alleviated. 

In the case of aromatic fractions an empirical correction for %Ca, the percentage of carbon in aromatic structure, can be applied ... 

Figure 3. IH NMR spectra of aromatic fractions from tar sands bitumen...

For this work they chose several types of base stocks—some were raffinates from solvent extraction and therefore contained different percentages of aromatics and some were blends of white oils (of near-zero aromatic content) with added quantities of aromatic fractions separated from bright stocks. Oxidations were performed at a number of temperatures with and without added metals (metallic iron and copper to simulate wear metals) and were followed by the oxygen uptake method. Their overall conclusion was that aromatics did indeed inhibit oxidation, whether metals were present or not, and that the effect with their samples exhibited a maximum at about 5% aromatics content. Figure 5.4 illustrates this phenomenon, with measurements of the time for uptake of 1800 ml of oxygen per 100 ml of sample. It can be seen that the reaction rate at zero and 8% aromatics is twice as fast as at 5% (times vary by a factor of two). It was clear that aromatics contained these naturally occurring inhibitors, but this work was unable to shine any light on just what these inhibitors were. 

Figure 4a. 13C NMR of aromatic fractions from Kuwait crude oil...

The 13C NMR spectra of aromatic fractions (Figure 9) and average parameter calculations therefrom (Table IX) indicate that biological reactions primarily occurred on the condensed aromatic rings and the... 

Figure 7. HPLC chromatogram of aromatic fraction from a fish sample...

GC/MS of aromatic fractions from core extracts of specific zones within the Kuparuk River Formation were analysed to determine the degree of depletion of long-chain alkyl aromatics. The core samples analysed were chosen based on available cores for their relationship to production issues (tar, oil quality and production rates). 

Candeli et al. 1974 (8) TABLE 1 - DISTILLATION CURVE AND COMPOSITION OF AROMATIC FRACTION OF A TYPICAL COMMERCIAL FUEL... 

Mechanistic studies carried out at low pressure, by using molecu lar beam sampling, indicate that PAH build up occurs through addi tion of aliphatic fragments to aromatic rings. Consequently, the presence of aromatic fractions in the fuel promotes formation of PAH. 

Muller et al. used SCS derivatives to study the effects of hydrodesulfurization (HDS) on polycyclic aromatic sulfur heterocycles (PASHs) in bitumen residua. Their experiments concentrated on PASHs, which is a predominant class of SCS in vacuum residue bottoms. Asphaltenes were removed by precipitation, followed by the separation of aromatic fractions from saturated fractions by the saturates, aromatics, resins, and asphalts (SARA) method. Several methods can be deployed as the SARA method depending on the type of petroleum sample, one of the more common for more viscous oils is a combination of two methods ASTM D2007 and ASTM D893. Pentane-insoluble (PI) method ASTM D893 is used first to identify the asphaltene content then ASTM D2007 is used to calculate the saturates, aromatics, and resins. 

Robinson, C.J. Cook, G.L., Low-resolution Mass Spectrometric Determination of Aromatic Fractions Irom Petroleum, /la/. Chem., 1969, 41(12), 1548-1554. 

A weight of aromatics fraction recovered, and B = weight of nonaromatics fraction recovered. 

Note 10—The procedure for analyzing 2 g of sample gives recoveries of aromatics fractions that are on average 0.35 weight % lower than the procedure for analyzing 10 g of sample. 

THIS routine gives THE ANALYSIS OF AROMATICS FRACTIONS FROM PETROLEUM USINR the procedure DESCRIBED IN ANAL CHFM 4l, 154R-5A (1969)... 

ASSEMBLE appropriate pfAKS IN MASS SPECTRUM OF AROMATIC FRACTION FOR processing in a 7 X 7 MATRIX. QUANTITIES A6.A7.A8.ETC. REFER initially to SUMS OF peaks AT 7 NUMBERS 6.7.8,ETC. A6.A8.ETC. ARE... 

PORMAT (IHl 9X.44HMASS SPECTRAL ANALYSIS OF AROMATIC FRACTIONS)... 

TABLE 4 Mass Spectral Analysis of Aromatic Fractions... 

Only insufficient information is available concerning the exchange of volatile aromatics between the atmosphere and water. It can be reliably assumed that rainfall precipitates volatile aromatics from the atmosphere, whereupon they are introduced directly or indirectly into surface water. The occurrence of aromatic fractions from automobile exhaust gases in Lake Zurich and the river Glatt, mentioned above, provides evidence that such an exchange actually does take place [64, 65] for other water ways see [67,68] and a later section [see also 291, 292]. 

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