Aromatic diesel compounds

Figure 6.4 Heterocyclic aromatic nitrogen compounds found in unpurified diesel.

The physical basis for this S5mergism in process application is based in the chemistry of the alkylated aromatic thiophenic compounds in diesel fuel feedstock those most resisitant to conversion to hydrocarbons by HDS are those most readily amenable to oxidation and extractive desulfurization. Refiners expanding their processing capacity or adjusting to the new ULSD rule may want to consider the new extractive desulfurization (EDS) alternatives to high severity HDS, including debottelnecking HDS units by feedstock pretreatment or post-treatment, or parallel operation to reduce the load on their units. 

This test method covers the determination of the total amounts of monoaromatic and polynuclear aromatic hydrocarbon compounds in motor diesel fuels, aviation turbine fuels, and blend stocks by supercritical fluid chromatography (SFC). The range of aromatics concentration to which this test method is applicable is from 1 to 7S mass %. The range of polynuclear aromatic hydrocarbon concentrations to which this test method is applicable is from O.S to SO mass %. 

Deep desulfurization of diesel fuels is particularly challenging due to the difficulty of reduce aromatic sulfur compounds, particularly 4,6-dialkyldibenzothiophenes, using conventional hydrodesulfurization processes (HDS). The HDS process is normally only effective for removing organosulfur compounds of aliphatic and alicyclic types. The aromatic sulfur molecules including thiophenes, dibenzothiophenes (DBT), and their alkylated derivatives are very difficult to convert to H2S through HDS. 

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... 

The term naphthenic acid, as commonly used in the petroleum industry, refers collectively to all of the carboxyUc acids present in cmde oil. Naphthenic acids [1338-24-5] are classified as monobasic carboxyUc acids of the general formula RCOOH, where R represents the naphthene moiety consisting of cyclopentane and cyclohexane derivatives. Naphthenic acids are composed predorninandy of aLkyl-substituted cycloaUphatic carboxyUc acids, with smaller amounts of acycHc aUphatic (paraffinic or fatty) acids. Aromatic, olefinic, hydroxy, and dibasic acids are considered to be minor components. Commercial naphthenic acids also contain varying amounts of unsaponifiable hydrocarbons, phenoHc compounds, sulfur compounds, and water. The complex mixture of acids is derived from straight-mn distillates of petroleum, mosdy from kerosene and diesel fractions (see Petroleum). 

I. L. Davies, K. D. Battle, P. T. Williams and G. E. Andrews, On-line fractionation and identification of diesel fuel polycyclic aromatic compounds by two-dimensional microbore liigh-peiformance liquid-cliromatography/capillary gas-cliiomatography . Anal. Chem. 60 204-209 (1988). 

Standardization. Standardization in analytical chemistry, in which standards are used to relate the instrument signal to compound concentration, is the critical function for determining the relative concentrations of species In a wide variety of matrices. Environmental Standard Reference Materials (SRM s) have been developed for various polynuclear aromatic hydrocarbons (PAH s). Information on SRM s can be obtained from the Office of Standard Reference Materials, National Bureau of Standards, Gaithersburg, MD 20899. Summarized in Table VII, these SRM s range from "pure compounds" in aqueous and organic solvents to "natural" matrices such as shale oil and urban and diesel particulate materials. 

Because process mixtures are complex, specialized detectors may substitute for separation efficiency. One specialized detector is the array amperometric detector, which allows selective detection of electrochemically active compounds.23 Electrochemical array detectors are discussed in greater detail in Chapter 5. Many pharmaceutical compounds are chiral, so a detector capable of determining optical purity would be extremely useful in monitoring synthetic reactions. A double-beam circular dichroism detector using a laser as the source was used for the selective detection of chiral cobalt compounds.24 The double-beam, single-source construction reduces the limitations of flicker noise. Chemiluminescence of an ozonized mixture was used as the principle for a sulfur-selective detector used to analyze pesticides, proteins, and blood thiols from rat plasma.25 Chemiluminescence using bis (2,4, 6-trichlorophenyl) oxalate was used for the selective detection of catalytically reduced nitrated polycyclic aromatic hydrocarbons from diesel exhaust.26... 

Aromatics, olefins and in general, unsaturated compounds undergo hydrogenation reactions, usually unwanted due to their detrimental effect on the operating costs, derived from an excessive consumption of hydrogen. Aromatic saturation, however, is used in jet fuel to improve the smoke point and in diesel for cetane enhancement. In the case of gasoline, extreme hydrogenation leads to a deterioration of the fuel performance parameters. 

Nitro polycyclic aromatic hydrocarbons are environmental contaminants which have been detected in airborne particulates, coal fly ash, diesel emission and carbon black photocopier toners. These compounds are metabolized Tn vitro to genotoxic agents through ring oxidation and/or nitroreduction. The details of these metabolic pathways are considered using 4-nitrobiphenyl, 1- and 2-nitronaphthalene, 5-nitro-acenaphthene, 7-nitrobenz[a]anthracene, 6-nitro-chrysene, 1-nitropyrene, 1,3-, 1,6- and 1,8-dinitro-pyrene, and 1-, 3- and 6-nitrobenzo[a] pyrene as examples ... 

SynSat [Synergetic Saturation] A process for removing aromatic hydrocarbons and sulfur compounds from diesel fuel. Developed by ABB Lummus Crest and Criterion Catalyst Company. Six units were operating in 1996. 

In the case of diesel fuel, an important property that defines the fuel quality is the cetane number (CN). Fuels with low-CN have poor ignition quality (i.e. knocking, noise, PM emissions) and make starting the engine difficult on cold days.6,7 It is well known that CN is lowest for PAHs and highest for w-paraffins.8,9 In normal paraffins, CN increases with the number of carbon atoms in the molecule. For naphthenic compounds and iso-paraffins the CN falls between those of aromatics and w-paraffins. In iso-paraffins, the CN decreases as the degree of branching increases.10... 

Aromatic compounds, 13 108-109 13 680. See also Aromatics acylation of, 12 173-181 amination of, 12 184 arylation of, 12 170-171 Cycloalkylation of, 12 169 in diesel fuel, 12 425 formylation of, 12 178 Friedel-Crafts acylation of, 12 174 Friedel-Crafts alkylation of, 12 164 nitration of, 12 182-183 oxidative coupling of, 19 654 sulfonation of, 12 181 sulfonation reagents for, 23 521-524 Aromatic-containing polymers, sulfonation of, 23 535-536... 

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