Deasphaltening

Two of the methods (ASTM D2007, D4124) use adsorbents to fractionate the deasphaltened oil, but the third method (ASTM D2006) advocates the use of various grades of sulfuric acid to separate the material into compound types. Caution is advised in the application of this method since the method does not work well with all feedstocks. For example, when the sulfuric acid method (ASTM D2006) is applied to the separation of heavy feedstocks, complex emulsions can be produced. 

Deasphaltened oil the fraction of petroleum after the asphaltenes have been removed. 

Deasphaltening removal of a solid powdery asphaltene fraction from petroleum by the addition of low-boiling liqnid hydrocarbons snch as n-pentane or n-heptane nnder ambient conditions. 

Maltenes that fraction of petroleum that is soluble in, for example, pentane or heptane deasphaltened oil q.v.y, also the term arbitrarily assigned to the pentane-soluble portion of petroleum that is relatively high boiling (>300°C, 760 mm) see also Petrolenes. 

Resins that portion of the maltenes iq.v.) that is adsorbed by a snrface-active material such as clay or alumina the fraction of deasphaltened oil that is insoluble in liqnid propane bnt solnble in n-heptane. 

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-... 

Deasphaltened oil the fraction of petroleum after the asphaltenes have been removed using liquid hydrocarbons such as n-pentane and n-heptane. 

Figure 1. IR spectrum of the sulfoxide and the corresponding sulfide fractions of deasphaltened Athabasca bitumen. (Reproduced with permission from Ref. 3. Copyright 1983 Pergamon Press Ltd.)...

Figure 3. z-Plots for the sulfoxide fraction of deasphaltened Athabasca bitumen as derived from FIMS (Figure 2). The z = -2, -4 and -6 traces have maxima at n = 13, 18 and 23, respectively. These substances differ by five carbon atoms (an isoprene unit) and one ring. (Reproduced with permission from Ref. 4. Copyright 1985, Alberta Oil Sands Technology and Research Authority.)...

Recently, Bunger et al. (I) have pointed out, on the basis of simple thermodynamic reasoning, that substantial overlaps must exist between the maltene (i.e., deasphaltened bitumen) and asphaltene fractions with... 

The separation of resin acids and bases has been described previously (II, 12), see also comments in (14). The percentage of resins, as determined for deasphaltened Athabasca bitumen by their separation on an Attapulgus clay column, was 34%, while combined acids, bases, and Lewis bases amounted to 25.9% of the whole bitumen. Thus, 8.1% of material retained as resins on Attapulgus clay did not interact with the ion exchangers or the complexation column and appeared in the polyaromatic fraction. The distribution of material within the resin fraction was 46.1% acids, 21.9% bases, and 32% neutral compounds. Thus, the pattern of acid and base distribution is similar for the resins and asphaltenes, except for a higher proportion of neutral material present in the resins. 

Feedstock Characteristics. The Sunnyside tar sand sample contains 9.3 wt % bitumen. The extracted bitumen was subjected to deasphaltening and results of three runs were 20.6, 19.9, and 21.4 wt % (20.6% average) of the total bitumen. The elemental analysis and physical properties of the bitumen,... 

The structure and chemistry of tar sand bitumen asphaltenes were studied indirectly by inference from processing and characterization of virgin bitumen and deasphaltened bitumen (maltenes). Results differ significantly from those derived from characterization of asphaltenes as isolated... 

Table I summarizes the analytical results for deasphaltened Athabasca bitumen (without prior distillation) on a series of columns used in the USBM-API 60 procedure, and those obtained by the simplified silica and alumina class separation scheme. As seen, the results are comparable provided that the polyaromatic and polar fractions are combined. The total analyses of the separated fractions obtained by the two methods listed in Table II are also in good agreement, with the exception that sulfur values from the simplified procedure are somewhat higher in all aromatic fractions except the polyaromatic/polar fraction.

The separation scheme for deasphaltened bitumen on silica [WOELM, activated at 140°C (4 hr)] is shown in Figure 1. The fractions obtained were loosely termed hydrocarbons. Polar I, II, and III. The IR spectra of these fractions, as shown in Figure 2, suggested that Polar I was very similar to the polyaromatic/neutral polar fraction from the API 60-based separation after removal of additional material from alumina with pure benzene. Also, simulated distillation curves for this fraction from either procedure are very similar (Figure 3). The IR spectra of the Polar II and III fractions show the presence of all the functional groups which can be distinguished in these complex mixtures and which... 

Figure 1. Separation of deasphaltened bitumen on silica and of Polar I fraction on alumina. The numbers in brackets are % of sample those outside...

Finally, during the fractionation of petroleum, the metallic constituents (metalloporphyrins and nonporphyrin metal chelates) are concentrated in the asphaltene fraction. The deasphaltened oils (petrolenes and maltenes) contain smaller concentrations of porphyrins than the parent materials and usually very small concentrations of nonporphyrin metals. 

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