Resins and asphaltenes

In crude oil, nitrogen is found mostly in fractions boiling over 250°C and is particularly concentrated in resins and asphaltenes. Nitrogen takes the following forms / to). ... 

In the heaviest fractions such as resins and asphaltenes (see article 1.2), metal atoms such as nickel and vanadium are found. They belong in part to molecules in the porphyrine family where the basic pattern is represented by four pyrrolic rings, the metal being at the center of this complex in the form Wi - or V0+ (< 3)... 

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... 

One major question of interest is how much asphaltene will flocculate out under certain conditions. Since the system under study consist generally of a mixture of oil, aromatics, resins, and asphaltenes it may be possible to consider each of the constituents of this system as a continuous or discrete mixture (depending on the number of its components) interacting with each other as pseudo-pure-components. The theory of continuous mixtures (24), and the statistical mechanical theory of monomer/polymer solutions, and the theory of colloidal aggregations and solutions are utilized in our laboratories to analyze and predict the phase behavior and other properties of this system. 

Table II. Resin and Asphaltene Content of Crude Oils (11)...

SARA analysis a method of analysis for saturates, aromatics, resins, and asphaltenes. 

One of the most ubiquitous multiple-component contaminants that reaches the soil and deeper subsurface layers is crude oil and its refined products. In the subsurface, these contaminants are transformed differently by various mechanisms (Cozzarelli and Baber 2003). Crude oil contains a multitude of chemical components, each with different physical and chemical properties. As discussed in Chapter 4, the main groups of compounds in crude oils are saturated hydrocarbons (such as normal and branched alkanes and cycloalkanes without double bonds), aromatic hydrocarbons, resins, and asphaltenes, which are high-molecular-weight polycyclic compounds containing nitrogen, sulfur, and oxygen. 

Table 10.2 presents the total coke yields and the nonvaporized hydrocarbons produced over a spent catalyst obtained with different feedstocks. The catalyst used was deactivated for 20 hours, 30 ReDox cycles, and 50% steam. When the 100% vacuum gas oil (VGO) is replaced with a mixture of 5%w DMO-VGO and/or 30%w DMO-VGO an increase of 30% and 120% in the coke yields was observed. While the spent catalyst from VGO cracking does not have adsorbed hydrocarbons, the mixture with DM0 does, becoming almost 1% for the mixture with 30%w DM0. The SARA (saturates, aromatics, resins, and asphaltenes) analysis of these hydrocarbons showed a high concentration of asphaltenes. 

Montan wax is a fossil plant wax with properties similar to natural plant waxes such as those found in carnauba palms. The material is a hard and has a high melting point. Montan wax is composed of a mixture of waxes, resins, and asphaltene-like materials. The wax is typically used in carbon inks, emulsions, polishes, and lubricants. 

The chemicals in petroleum are classified as paraffins, naphthenes, aromatics, and resins-asphaltenes. We have discussed the first three classes, which are hydrocarbons. Now we turn to resins and asphaltenes. 

The basic structures of resins and asphaltenes are similar. Both can be formed by oxidation of polycyclic aromatic hydrocarbons. On the other hand, both can be reduced to hydrocarbons by hydrogenation, which yields moderate to large hydrocarbon molecules, hydrogen sulfide, and water. Further, resins can be converted to asphaltenes by oxidation. 

There are, however, important differences between resins and asphaltenes. Asphaltenes do not dissolve in petroleum but are dispersed as colloids. Resins readily dissolve in petroleum. Pure asphaltenes are solid, dry, black powders and are nonvolatile. Pure resins are heavy liquids or sticky solids and are as volatile as hydrocarbons of the same size. The resins of high molecular weight are red the lighter resins are less colored. 

The color of petroleum is determined largely by the quantity of resins and asphaltenes present, although the greenish cast of some crude oils is probably due to the presence of molecules containing six or more rings. 

Sulfur Compounds — Oxygen Compounds—Nitrogen Compounds — Organometallic Compounds Resins and Asphaltenes 40... 

The resins and asphaltenes from tar sands and from the other synthetic fuels have not been analyzed beyond the extent shown by the tables. The resins can be fractionated and analyzed in more detail using methods developed for petroleum resins by Jewell (46) and McKay (47), but more extensive work is necessary to have definitive analysis methods for these materials. 

Petroleum can be fractionated into four generic types of materials representing general chemical properties. These include saturated hydrocarbons, aromatic hydrocarbons, resins, and asphaltenes. The standard ASTM separation procedure (D2007) for isolating the asphaltenes and the other components in petroleum is based on solubility behavior and chromatography, as shown in Fig. 5. Commerically, many refineries utilize solvent separations to produce a solvent deasphalted oil which has lower impurity levels. 

Feed source may also have a substantial effect on the distribution parameter (Tamm et al., 1981). Given the complexity of crude oil with reference to residuum properties, it is not surprising that differences in metal distribution parameters are observed. This finding suggests that optimal catalyst properties may vary with the residuum source. Galliasso et al. (1985) have compared the HDM kinetics of porphyrins and nonporphyrin compounds in both resins and asphaltenes. The individual... 

In general, the fractions produced by these different techniques are called saturates, aromatics, resins, and asphaltenes (Figure 3-9). And much of the focus... 

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. 

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. 

The nitrogen in fuels consists of complex, mostly heterocyclic compounds. In petroleum crudes, these include pyrroles, indoles, isoquinolines, acridines, and porphyrins. During refining most of these concentrate in the heavy resin and asphaltene fractions, which might suggest their relatively late release in the... 

While asphalt itself consists of a complex colloidal dispersion of resins and asphaltenes in oils, introduction of liquid elemental sulfur, which on cooling congeals into finely dispersed crystalline sulfur particles and in part reacts with the asphalt, necessarily complicates the rheology of such a SA binder. Differences and changes with SA binder preparation, curing time, temperature etc. must be expected and may be demonstrated by viscosity characteristics. 

---