Aromatic compounds in gasoline

G. S. Frysinger, R. B. Gaines and E. B. Ledford-Jr, Quantitative determination of BTEX and total aromatic compounds in gasoline by comprehensive two-dimensional gas chromatography (GC X GC) , 7. High Resolut. Chromatogr. 22 195-200 (1999). 

B) The percentage of aromatic compounds in gasoline i Variation of the percentage of aromatic parts in gasoline significantly influence the amount of PAH emitted (fig. 9). 

Muller MD, H-R Buser (1986) Halogenated aromatic compounds in automotive emissions from leaded gasoline additives. Environ Sci Technol 20 1151-1157. 

FCC Gasoline. The produced light FCC gasoline typically contains a mixture of paraffins, olefins, and aromatic compounds in a ratio of around 5 3 2. This ratio will often vary depending upon feedstock, catalyst quality, and reactor parameters. The research octane number of FCC gasoline will typically be much higher than the motor octane number. 

The non-selective FID does not provide the second detector confirmation for BTEX, whereas the PID has only a marginal selectivity to aromatic compounds. In a typical analysis of gasoline in water by EPA Method 8021, benzene and MTBE results tend to be biased high due to coelution with other constituents false positive results are also common. 

Acid Extraction. Strong sulfuric acid not only reacts with many sulfur compounds in gasolines at room temperature, but also with aromatic and unsaturated compounds however, when the temperature is dropped to 15° to 20° F., the acid is capable of dissolving the sulfur compounds while its activity toward unsaturates and aromatics has been diminished considerably (113, 131), thus making a selective removal of the sulfur compounds feasible. Dilution of the acid with water regenerates the sulfur compounds however, these compounds may not necessarily be the same as were originally present in the naphtha, particularly if the acid treatment was not maintained at the low temperature. 

Ostman CE, Colmsjo AL, Zebuehr Y. 1986. Polycyclic aromatic compounds in lubricating oil A study of gasoline, gasoline/methanol, gas and diesel fueled engines. In Cooke M, Dennis AJ, eds. Polycyclic aromatic hydrocarbons Chemistry, characterization, and carcinogenesis. Proceedings of the Ninth International Symposium. Columbus, OH Battelle Press, 729-744. 

The greatest problem during thermal cracking arises from reactions involving aromatic feed. Aromatic compounds in the feed have a very high tendency to undergo polycondensation reactions that lead to coke formation. Coke formation decreases the yields of the desired gasoline and diesel fractions. One example of a polycondensation reaction is shown in reaction (6.7). 

Alkyl substituents diminish the retention of aromatic compounds in nonpolar eluents (like hexane/chloroform mixtures), which is the opposite tendency to the retention under RP conditions in water/propanol-2 polar eluents. As hypercrosslinked polystyrene is compatible with both the above types of mobile phases, by just adding propanol-2 to a nonpolar mobile phase it is possible to mutually cancel the above contributions of alkyl substituents. As a result, only compounds having a different number of aromatic rings will separate, due to the difference in their susceptibility to TT-TT-interactions. This presents an opportunity to perform either a full resolution of a mixed aromatic sample or a group separation into mono-, hi-, and tricyclic aromatics on the same column by just running the analysis under RP, quasi-normal phase, or mixed-mode conditions (Fig. 13.9). A practical example of such sensitive group analysis of aromatics in real gasoline samples can be found in [197]. 

II) Preferentially two parameters influence the mass concentration and the profiles of PAH in the exhaust (a) ratio of gasoline-air mixture, and (b) percentage of aromatic compounds in the gasoline ... 

In recent years, several studies have evaluated the benefits of the abovementioned, applying an electric field to enhance the biodegradation process in polluted soil samples with different compounds, aromatic compounds, herbicides, gasoline hydrocarbons, or trichloroethylene [5-8]. With the aim to increase the solubility of the organic-forming complexes and/or increase the electroosmotic flow, the use of chemical or biological surfactants has been assayed in some studies [9, 10]. 

The distillative pyrolysis oil fractionation produces C5, Cg, C7, Cg, and C9+ product streams. The C5 fraction is frequently used for fuel production (Otto fuel) while the C9+ fraction is added to the gasoline pool. The individual Cg-Cg fractions undergo additional steps to separate the aromatic compounds from the respective non-aromatic compounds with the same carbon number. Depending on the relative amount of aromatic compounds in each fraction these separations are carried out using extractive distillation, extraction, or adsorption processes. Note that the pygas of the naphtha steam cracker is - besides the reforming process in refineries, see... 

Symbol for gas oil in the three lump model, aromatic compounds in the 8-lump model Symbol for gasoline lump in the three lump model Symbol for light gases plus coke lump Concentration of gas oil (gmol/cm )... 

The distinction of aliphatic isomers and homologues in crude oil and gasoline fractions by IR spectroscopy is a hard task. However, the method is very powerful if the identification of aromatic compounds in oil fractions is required. The discrimination ability of... 

Aromatics Content. Aromatic compounds have very poor ignition quahty and, although they are not specifically limited in ASTM D975, there are practical limitations to using high aromatic levels in highway diesel fuel. In the United States, where gasoline demand represents about one-half of the... 

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