Maltenes

Resins have similar components to asphaltenes but they are soluble in w-heptane. They are solid or semi-solid, dark brown in colour and strongly adhesive. Resins are dispersing agents to asphaltenes and their proportion to asphaltenes control the gel/sol type of character of bitumen. Their molecular weight is lower than asphaltenes. 

Aromatics are naphthenic aromatic hydrocarbons, have the lowest molecular weight of the compounds in the bitumen and represent the main dispersion medium of asphaltenes. They are viscous fluids of dark brown colour and they can be found at 40% to 65% in bitumen. 

Saturates are aliphatic hydrocarbons together with alkyl naphthenes and alkyl aromatics. Their molecular weight is similar to the molecular weight of aromatics and their components contain both waxy and non-waxy saturates. Saturates are light yellow to white in colour and its content ranges from 5% to 20% in bitumens. 

During fractional distillations (atmospheric or with vacuum), the lightest volatile ingredients of the bitumen are removed, which results in an increase in asphaltene concentration. Asphaltene concentration also increases during the oxidation (air-blowing) process. This fact makes the bitumen harder and less susceptible to temperature variations (increase of the penetration index value). 

The observed change in bitumen composition during distillation and air-blowing is demonstrated in Shell Bitumen (2003). 

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The portion that is soluble in normal heptane is given the term maltenes. 

If maltenes are subjected to liquid chromatography (see 2.1.2.4) the components eluted by the more polar solvents are called resins. Their composition, once again, depends on the procedure used. 

Liquid chromatography is preceded by a precipitation of the asphaltenes, then the maltenes are subjected to chromatography. Although the separation between saturated hydrocarbons and aromatics presents very few problems, this is not the case with the separation between aromatics and resins. In fact, resins themselves are very aromatic and are distinguished more by their high heteroatom content (this justifies the terms, polar compounds or N, S, 0 compounds , also used to designate resins). 

Asphaltenes seem to be relatively constant in composition in residual asphalts, despite the source, as deterrnined by elemental analysis (6). Deterrnination of asphaltenes is relatively standard, and the fractions are termed / -pentane, / -hexane, / -heptane, or naphtha-insoluble, depending upon the precipitant used (5,6,49). After the asphaltenes are removed, resinous fractions are removed from the maltenes-petrolenes usually by adsorption on activated gels or clays. Recovery of the resin fraction by desorbtion is usually nearly quantitative. 

Colloidal State. The principal outcome of many of the composition studies has been the delineation of the asphalt system as a colloidal system at ambient or normal service conditions. This particular concept was proposed in 1924 and described the system as an oil medium in which the asphaltene fraction was dispersed. The transition from a coUoid to a Newtonian Hquid is dependent on temperature, hardness, shear rate, chemical nature, etc. At normal service temperatures asphalt is viscoelastic, and viscous at higher temperatures. The disperse phase is a micelle composed of the molecular species that make up the asphaltenes and the higher molecular weight aromatic components of the petrolenes or the maltenes (ie, the nonasphaltene components). Complete peptization of the micelle seems probable if the system contains sufficient aromatic constituents, in relation to the concentration of asphaltenes, to allow the asphaltenes to remain in the dispersed phase. 

In 1973 Thiele and Malten [74] found in skin dermatitis, skin resistance, and water loss studies no negative effect using the sodium salt of a laurylpolyglycol ether carboxylic acid with 3.8 mol EO. 

Bitumen contains a solvent-soluble fraction referred to as maltenes, and an insoluble fraction called asphaltenes. The word bitumen is in some cases also used to indicate the residue of the distillation of petroleum. 

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. 

Petrolenes the term applied to that part of the pentane- or heptane-solnble material that is low boiling (<300°C, <570°F, 760 mm) and can be distilled withont thermal decomposition see also Maltenes). 

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. 

Dermal Effects. Completely destroyed stratum comeum was observed in the skin of 2 young volunteers exposed to chloroform for 15 minutes on 6 consecutive days (Malten et al. 1968). Milder changes were observed in two older individuals. Chloroform was applied in a glass cylinder (exact exposure was not specified). 

Dermal Effects. No reports are available on the toxicity of chloroform to skin after inhalation and oral exposures in humans. Stratum comeum damage was reported after a topical exposure of chloroform of 15 minutes duration for 6 consecutive days (Malten et al. 1968). Chloroform was used as a vehicle for the topical application of aspirin for the treatment of painful herpes zoster lesions in male and female humans. The only reported side-effect was an occasional burning sensation to the skin as the chloroform evaporated after application (King 1993). 

Malten KE, Spruit D, Boemaars HGM, et al. 1968. Homy layer injury by solvents. Bemfsdermatosen 16 135-147. 

Malten, W. G. Van Ketel, and E. Van SI107 Dijk. Allergens in sesame oil contact dermatitis. Acta Derm 1975 55 31-34-... 

A significant portion of the sulfur- and nitrogen-containing species in crude oil can be found in heterocyclic form within the asphaltene, maltene, and resin compounds. Oxygen-containing heterocycles may also be present. Examples of high-molecular-weight aromatic, resinous, and polar compounds found in crude oil are provided in TABLE 3-1. 

Asphaltenes These are complex high-molecular-weight polycyclic aromatic compounds which may contain oxygen, sulfur, or nitrogen heteroatoms. They are found in crude oil and in certain heavy fuel oils in micellar form. Their dispersion throughout oil can be stabilized by asphaltene precursors called resins and maltenes. 

Boduszynski et al. (1980) also employed the more conventional separation procedure based on solubility properties (Corbett, 1969) to provide asphaltene and maltene samples from the 675°C+ residuum. Asphaltenes are isolated by precipitation in an alkane solvent, with further separation of maltenes by chromatography in solvents of increasing elution strength. The FIMS results in Fig. 9 illustrate, significantly, that asphaltenes are not necessarily the highest-molecular-weight components in residuum. Asphaltenes have, rather, a relatively low but broad distribution of molecular weights. 

Asphaltenes may contain both porphyrin and nonporphyrin metals, depending upon the origin of the crude oil. Yen et al. (1969) characterized the vanadium complexes in a petroleum asphaltene by mass spectroscopy, optical spectroscopy, and ESR. Porphyrins (Etio and DPEP), acid-resistant porphyrin macrocycles of increased aromaticity (Rhodo), and nonporphyrins with mixed donor complexes were identified. Baker (1966) and Baker et al. (1967) extracted porphyrins from Boscan crude oil asphaltenes and also found Etio and DPEP as the two major porphyrin series. These homologous series range in molecular weight by 7 to 18 methylene groups. Gallegos (1967) observed by mass spectroscopy that asphaltenes and maltenes from a Boscan crude oil had nearly identical porphyrins in terms of mass distribution. 

Percent Vanadium in Each Molecular Weight Category of Vanadyl Compounds in the Four Heavy Crude Petroleums and Their Asphaltenes, Maltenes, Asphaltene Polar Extracts, and Extracted Asphaltenes by 50/100/1000 A SEC-HPLC-GFAA Analysis"- ... 

Vanadyl salen provides a model of mixed heteroatom metal coordination characteristic of Ni and VO in the maltenes and asphaltenes. Approximately 50-90% of the metals in petroleum are not contained in the free porphyrin fraction. Yen (1975, 1978) has postulated that these metals exist in a variety of environments such as highly aromatic bound porphyrins, complexed to tetradentates of mixed N, S, and O ligands, or defect sites in large aromatic sheets. Analytical work by Fish et al. (1984) has indicated the presence of metals complexed to salen-type ligands in petroleum. 

Panzer t al. (5) extracted Athabasca tar sand in two steps, the first with compressed n-pentane (Tc = 570 K, Pc = 3.37 MPa) and the second with compressed benzene (Tc = 563 K, Pc = 4.92 MPa). At 533-563 K and 2.0-7.7 MPa, n-pentane extracted 95% of the maltenes and asphaltenes from the tar sand, whereas at atmospheric pressure only 75% was extracted. Further extraction with benzene at 633 K and 2.0 MPa removed the remaining higher molecular weight asphaltenes. This indicates that the chemical nature of the dense gas is important in some applications. 

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