Aromatic concentrate, hydrocarbon types

Sulfur compounds in the gas oil fractions from two bitumens (Athabasca oil sand and Cold Lake deposit)> a heavy oil (Lloydminster) from Cretaceous reservoirs along the western Canada sedimentary basin, and a Cretaceous oil from a deep reservoir that may be mature (Medicine River) are investigated. The gas oil distillates were separated to concentrates of different hydrocarbon types on a liquid adsorption chromatographic column. The aromatic hydrocarbon types with their associated sulfur compounds were resolved by gas chromatographic simulated distillation and then by gas solid chromatography. Some sulfur compounds were further characterized by mass spectrometry. The predominant sulfur compounds in these fractions are alkyl-substituted benzo- and dibenzothiophenes with short side chains which have few dominant isomers. 

The analysis of Prudhoe Bay Crude Oil for the hydrocarbon components under study is presented in Table V, together with the percentage of the total hydrocarbons found represented by each of the hydrocarbon types. For comparison, the contribution of component types to the total hydrocarbon is listed for both a filtered and unfiltered seawater suspension. The comparison is somewhat biased because benzene was not determined in the crude oil, being poorly separated from the hexane solvent, and because C4-benzenes were not determined in the unfiltered sample. However, it can be readily seen from the results that while aromatic hydrocarbon types are present in the crude oil in roughly equal concentrations, the preponderance of the total hydrocarbons in the seawater suspension is composed of the low-molecular-weight aromatic hydrocarbons. In both unfiltered and filtered systems, 90% of the water-soluble aromatic hydrocarbons found are composed of benzene, toluene, ethyl benzene, and the xylenes. This is in contrast to their concentration in the whole crude oil, which is at most a few percent and where their contributions to the hydrocarbons analyzed for is probably less than 30%. 

Samples are separated into saturate and aromatic fractions by Method D 2549, and each fraction is analyzed by mass spectrometry. The analysis is based on the summation of characteristic mass fragments to determine the concentration of hydrocarbon types. The average carbon numbers of the hydrocarbon types are estimated from spectral data. Calculations are made from calibration data dependent upon the average carbon number of the hydrocarbon types. The results of each fraction are mathematically combined according to their mass fractions as determined by the separation procedure. Results are expressed in mass percent. 

The overall reaction scheme by which high concentrations of aromatics are produced in Powerforming is rather complex. However, it can be broken down into four important and distinct types of reactions. In Figure 1, these four reactions are illustrated by the reactions of hydrocarbon feed components. 

The environmental occurrence of polycyclic aromatic hydrocarbons is mainly associated with dispersion of oil products and with various types of combustion. For these chemicals a kind of pre-industrial background exists, due to forest fires or to domestic wood burning. The sediments of the deepest strata were certainly deposited in the nineteenth century, when no significant industrial activities had been initiated. The ratio between PAH concentrations found in the sediments dated to this century, and the deepest ones, vary from 1.7 to 30, increasing from the beginning of the... 

Now and then, projectiles from outer space cause excitement and surprises, as in January 2000, when a meteorite impacted the frozen surface of Lake Targish in Canada. It was a new type of C-chondrite with a carbon concentration of 4-5%, and probably came from a D-type asteroid (Hiroi et al., 2001). More exact analysis of the Targish meteorite showed the presence of a series of mono- and dicarboxylic acids as well as aliphatic and aromatic hydrocarbons (Pizzarello et al., 2001). Aromatic compounds and fullerenes were detected in the insoluble fraction from the extraction this contained planetary helium and argon, i.e., the 3He/36Ar ratio was... 

The simplest systems where electron-transfer chemiluminescence occurs on interaction of radical ions are radical-anion and radical-cation recombination reactions in which the radical ions are produced from the same aromatic hydrocarbon (see D, p. 128) by electrolysis this type of chemiluminescence is also called electro-chemiluminescence. The systems consisting of e.g. a radical anion of an aromatic hydrocarbon and some other electron acceptor such as Wurster s red are more complicated. Recent investigations have concentrated mainly on the energetic requirements for light production and on the primary excited species. 

To reveal factors which influence activities of acid-base catalysts in alkylation and isomerization is the challenge to activity in this field. Q he greatest amount of work has been done in connection with the effect of para-selectivity, which is observed in alkylation of aromatic hydrocarbons on ZSM-5 type zeolites [1]. This effect has been explained by a number of authors either by the influence of diffusion factors [2,3] or by the isomerizing activity of the external surface of zeolite crystals [4]. In refs. [5,6] and especially in ref.[7] the para-selective effect of ZSM-5 type zeolites is shown to be due to decreasing their isomerizing activity becaiase of the decrease in the concentration of strong protic centres as a result of modifiers introduced. Para-selective effect is related to the action of chemical factors. However, in... 

Particular attention should be paid to the possibility of singlet interactions when aromatic hydrocarbons and other compounds which fluoresce are employed as sensitizers. Unambiguous evidence for this phenomenon can be obtained from the effect of acceptor on sensitizer fluorescence and it can be minimized by the use of low acceptor concentrations. Interestingly, not all aromatic hydrocarbons engage in the type of quenching158 that seems to involve charge transfer for example, triphenylene fluorescence is not affected by piperylene.160... 

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