Saturates aromatics separation

Repeatability of the Saturates—Aromatics Separation. Results obtained with the dual detectors for ten individual injections of a 20-vol % solution of a vacuum gas oil in n-heptane are shown in Table IV. The precision (2(t) for the saturates and aromatics area response from the RI detector was 6%, relative. The precision for the aromatics/ saturates response ratio was 6.9%, relative. The retention volumes were much more reproducible and had 2(7 values of the order of 1-3%, relative. 

Petroleum crude oil, gas condensate, and natural gas are generally complex mixtures of various hydrocarbons and nonhydrocarbons with diverse molecular weights. In order to analyze the contents of a petroleum fluid it is a general practice to separate it first into five basic fractions namely, volatiles, saturates, aromatics, resins, and asphaltenes [74, 77]. Volatiles consist of the low-boiling... 

Heavy hydrocarbons were obtained by solvent extraction (4) of sediments, deasphalting with pentane, and separation by liquid chromatography (5) into saturate, aromatic, NSO-eluted, and asphaltene fractions. Saturate fractions were analyzed by gas-liquid chromatography (6) on these chromatograms (Figures 4 and 6) n-paraffins stand up as peaks above the naphthenic background. 

Saturated and aromatic hydrocarbons were separated from the acid-, base-, and neutral nitrogen-free bitumen by adsorption chromatography using silica gel, grade 12, as the adsorbent and cyclohexane as the eluting solvent. The column was dry packed, and the cutpoint was made at two void volumes. At the cut points, the UV absorbance was measured at 270 nm to determine the overlap of aromatics in the saturates. Aromatics were desorbed with 60% benzene-40 % methanol. 

Upgrading of heavy oils and residua can be designed in an optimal manner by performing selected evaluations of chemical and structural features of these heavy feedstocks (Schabron and Speight, 1996). The evaluation schemes do not need to be complex, but must focus on key parameters that affect processability. For example, the identification of the important features can be made with a saturates-aromatics-resins-asphaltene separation (Chapter 3). Subsequent analy-... 

In general terms, group-type analysis of petroleum is often identified by the acronyms for the names PONA (paraffins, olefins, naphthenes, and aromatics), PIONA (paraffins, Ao-paraffins, olefins, naphthenes, and aromatics), PNA (paraffins, naphthenes, and aromatics), PINA (paraffins, Ao-paraffins, naphthenes, and aromatics), or SARA (saturates, aromatics, resins, and asphaltenes). However, it must be recognized that the fractions produced by the use of different adsorbents will differ in content and will also be different from fractions produced by solvent separation techniques. 

The region of the map below the pentane-insoluble boundary corresponds to pentane-deasphalted oil from the original residuum. The saturate, aromatic, and polar fractions were separated by adsorption of the deasphalted oil over clay. The saturate fraction shows a zero carbon residue and the aromatic fraction is only a little higher at 0.7%. The coke-forming constituents in the deasphaltened oil are the polar aromatics that have a carbon residue of 15.4. The carbon residue balance shown in the insert table shows that almost all of the coke-forming mate-... 

Bulk composition the make-up of petroleum in terms of bulk fractions such as saturates, aromatics, resins, and asphaltenes, separation of petroleum into these fractions is usually achieved by a combination of solvent and adsorption (q.v.) processes. 

SARA separation a method of fractionation by which petroleum is separated into saturates, aromatics, resins, and asphaltene fractions. 

Separation of an Asphalt—Method 2. Asphalt samples were separated into six fractions acids, bases, saturates, aromatics-1, aromatics-2, and aromatics-3. Acids were isolated using anion exchange resin, and bases were isolated using cation exchange resin. The remaining fraction (asphalt, less acids and bases) was separated on alumina using the same procedure as in Method 1 for the separation of maltenes. The separation scheme is shown in Figure 3. 

Separations. The asphaltene fractions were obtained by solvent extraction with benzene and subsequent precipitation with cyclohexane. The cyclo-hexane-soluble fractions were separated into saturate, aromatic, and polar aromatic fractions by the clay-gel technique, ASTM D-2007 (modified). This separation is also applicable to asphaltenes. 

Important analyses for the whole crude are as follows, including a liquid chromatographic separation adapted from the published SARA procedure (Saturates-Aromatics-Resins-Asphaltenes) for isolation of seven classes of compounds from mid-distillate (9). 

Column Chromatography. Column chromatography of the solvent refining or liquefaction samples was done in a manner described previously (II). The sample (.2 g) was dissolved in THF or chloroform and pre-adsorbed on 2 g of neutral alumina. The solvent was removed under vacuum, and the alumina with sample was added to an 11-mm o.d. glass column containing an additional 6g of neutral alumina (Activity I). Separation into saturates, aromatics, and various polar materials was done by elution with hexane, toluene, chloroform (two fractions), and 9 1 THF/ethanol. 

The oils and bitumen were separated chromatographically on silica gel into saturates, aromatics, polar aromatics, and asphaltenes fractions by the SAPA method of Barbour et al. (8). 

The vacuum distillate from Paraho shale oil crude was separated on silica gel into three fractions - saturate, aromatic, and polar. The carbon-13 NMR spectra indicated that these fractions contained 58, 15 and 36 percent,... 

The vacuum distillate was separated on silica gel into saturate, aromatic, and polar fractions by the procedure described earlier (4). The vacuum distillate comprised 33% of the crude shale oil and contained 1.82% (W/W) of nitrogen. The... 

Bitumen can be separated into a variety of fractions using a variety of techniques that have been used since the beginning of petroleum science. In general, the fractions produced by these different techniques are called saturates, aromatics, resins, and asphaltenes. Much of the focus has been on the asphaltene fraction because of its high sulfur content and high cokeforming propensity. 

Group type analysis methods are designed to separate hydrocarbon mixtures into classes such as saturates, aromatics and polars. As described previously,... 

For a PIONA-type GCxGC analysis of middle distillates, Vendeuvre et al. developed an analysis system containing a column to retain olefinic compounds [9]. The eluents of this column were subsequently released from this column and separated further just after the separation of the rest of the sample. The final result produced by the system consists of saturates, olefins, and aromatics separated by carbon number. 

One of the most used procedures, an ASTM standard, D4124, was developed by Corbett (61) and separates asphalt into four fractions. Asphaltenes are precipitated by heptane, and the remaining solution is divided into saturates, naphthene aromatics, and polar aromatics by a series of successively more polar solvents on an alumina column. Similar procedures produce fractions variously known as asphaltenes, resins, and oils or saturates, aromatics, resins, and asphaltenes, for example. Although similar, the methods are not identical and produce fractions that overlap those of other methods. 

Asphalt is thought of as a colloidal system similar to petroleum, the difference being that the lighter molecules have been removed from asphalt during the refining process. Asphalt can be fractionated into four important fractions saturates, aromatics, resins, and asphaltenes by either the SARA method or the ASTM D4124 process (standard test method for separation of asphalt into four fractions). The fractionated part of saturates and aromatics is generally considered to be gas-oil. The polarity of these four fractions increases from saturates —> aromatics —> resins —> asphaltenes. 

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. 

Most separations are carried out utilizing one separation principle however, multidimensional separations can also be performed. By coupling three packed columns (Figure 5.10), crude oils dissolved in carbon disulfide could be separated into three groups saturates, aromatics, and polars. The saturates eluted directly through all three columns to the flame ionization detector - the first, CN-1, column retained the polars, while the next CN-2 and Ag (silver nitrate on SCX) columns retained aromatics. Aromatics were backflushed from the last two columns, and... 

Figure 5.11 Group separation oftwo North Sea crude oils, one light (a) and one medium heavy (b), both deasphalted into saturates, aromatics, and polars. (From Ref. [7] with permission.)...

Conversion (upgrading) of bitumen and heavy oils to distillate products requires reduction of the MW and boiling point of the components of the feedstocks. The chemistry of this transformation to lighter products is extremely complex, partly because the petroleum feedstocks are complicated mixtures of hydrocarbons, consisting of 10 to 10 different molecules. Any structural information regarding the chemical nature of these materials would help to understand the chemistry of the process and, hence, it would be possible to improve process yields and product quality. However, because of the complexity of the mixture, the characterization of entire petroleum feedstocks and products is difficult, if not impossible. One way to simpHfy this molecular variety is to separate the feedstocks and products into different fractions (classes of components) by distillation, solubility/insolubility, and adsorption/desorption techniques. For bitumen and heavy oils, there are a number of methods that have been developed based on solubility and adsorption. The most common standard method used in the petroleum industry for separation of heavy oils into compound classes is SARA (saturates, aromatics, resins, and asphaltenes) analysis. Typical SARA analyses and properties for Athabasca and Cold Lake bitumens, achieved using a modified SARA method, are shown in Table 1. For comparison, SARA analysis of Athabasca bitumen by the standard ASTM method is also shown in this table. The discrepancy in the results between the standard and modified ASTM methods is a result of the aromatics being eluted with a... 

The chemistry of resid upgrading is extremely complicated. " This is in part due to the complexity of the ehemical nature of the feedstoeks. In order to understand the chemistry of upgrading, it would be helpful to reduee this complexity prior to reaction, by separating the feedstocks (bitumen and heavy oils) into well-known components such as SARA - saturates, aromatics, resins and asphaltenes - which are useful tools in understanding bitumen chemistry. 

Analytical methods such as thin layer chromatography with flame ionization detection (TLC-FID) (Karlsen barter, 1991) are widely used in the oil industry. These solubdity based separation methods allow for the investigation of crude oil components based on polarity. However they can yield very different amounts of Saturates, Aromatics, Resins and Asphaltenes (SARA) depending on the nature of solvents used in the sepraration. At a p>anel discussion on standardization of petroleum fractions held at the 2009 Petrophase conference, a need to unify and improve the separation methods for asphaltenes and resins was expressed (Merino-Garcia et al., 2010). The diversity of operating definitions employed and measurement variability affect the ability of researchers to determine whether compound classes are present and to draw cross-comp>arisons among measurements from different... 

These components can be separated by simple technique known as SARA analysis (Saturated, Aromatic, Resin and Asphaltenes). Some examples of the resin and asphaltenes that can be separated by using SARA analysis of are given in Figure 7a b. The SARA analysis process is shown in Figure 8. Particles such as silica, clay, iron oxides, etc. can be... 

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