Petroleum cuts

The possibility of cofeeding plastic wastes with petroleum cuts such as vacuum gas oil (VGO) [110], Arabian fight petroleum residues [111], light cycle oil [84], lube oils [88] or even raw chemicals such as benzene [85] has been widely investigated in the literature. The underlying aim is to reduce the high viscosity of the molten plastics. However, there is a limit since the maximum amount of plastics in the mixture to achieve a convenient rheological behaviour must be at most within 5-10 wt%. 

Arandes et al. [84] studied the catalytic degradation of several plastics (polypropylene, polystyrene, polystyrene-polybutadiene) dissolved in a light cycle oil (ECO) in a riser simulator of a ECC unit using both a fresh and an equilibrated ECC catalysts. Similarly, De la Puente [85, 112] studied the catalytic degradation of styrene-based polymers dissolved in benzene streams in the same riser simulator. Although the reported results are promising, oil refiners are reluctant regarding the inherent risks for the normal operation of the refinery units. 

Additionally, these authors also found that the presence of lube oil decreased the activity of the catalysts due to the presence of both sulphur- and nitrogen-containing compounds (4000 ppm of sulphur and 85 ppm of nitrogen) that poisoned the acid sites. Consequently, higher temperatures (450-500°C) should be employed to obtain complete conversion in the catalytic cracking of the LDPE-lubricating oil mixture over Al-MCM-41 and nanocrystalline HZSM-5 catalysts. 

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Fractionation and Elemental Analysis of Crude Oils and Petroleum Cuts... 

Chaptar 2. FRACTIONATION AND ELEMENTAL ANALYSIS OF CRUDE OILS AND PETROLEUM CUTS... 

The determination of the elemental composition of a petroleum cut is of prime importance because it provides a quick means of finding out the quality of a given cut or determining the efficiency of a refining process. In fact, the quality of a cut generally increases with the H/C ratio and in all cases, with a decrease in hetero-element (nitrogen, sulfur, and metals) content. 

The complexity of petroleum products raises the question of sample validity is the sample representative of the total flow The problem becomes that much more difficult when dealing with samples of heavy materials or samples coming from separations. The diverse chemical families in a petroleum cut can have very different physical characteristics and the homogeneous nature of the cut is often due to the delicate equilibrium between its components. The equilibrium can be upset by extraction or by addition of certain materials as in the case of the precipitation of asphaltenes by light paraffins. 

Chapter 2. FrACVONATION AND ELEMENTAL ANALYSIS OF CRUDE OlLS AND PETROLEUM CuTS... 

Experience has shown that certain carefully selected physical properties could be correlated with the dominant composition of a petroleum cut or crude oil. 

To extend the applicability of the characterization factor to the complex mixtures of hydrocarbons found in petroleum fractions, it was necessary to introduce the concept of a mean average boiling point temperature to a petroleum cut. This is calculated from the distillation curves, either ASTM or TBP. The volume average boiling point (VABP) is derived from the cut point temperatures for 10, 20, 50, 80 or 90% for the sample in question. In the above formula, VABP replaces the boiling point for the pure component. 

Characterization of a Petroleum Cut by Refractive Index, Density, and Molecular Weight (ndM method)... 

Refractive index this is one of the most precise measurements that can be carried out on a petroleum cut. The ASTM method D 1218 indicates a reproducibility of 0.00006, which is exceptional. 

Molecular weight for a mixture of components such as one would encounter in petroleum cuts, the molecular weight is ... 

Mass spectrometry allows analysis by hydrocarbon family for a variety of petroleum cuts as deep as vacuum distillates since we have seen that the molecules must be vaporized. The study of vacuum residues can be conducted by a method of direct introduction which we will address only briefly because the quantitative aspects are ek r metiy difficult to master. Table 3.6 gives some examples the matrices used differ according to the distillation cut and the chemical content such as the presence or absence of olefins or sulfur. 

It is common that a mixture of hydrocarbons whose boiling points are far enough apart petroleum cut) is characterized by a distillation curve and an average standard specific gravity. It is then necessary to calculate the standard specific gravity of each fraction composing the cut by using the relation below [4.8] ... 

The temperatures 100°F and 210°F (37.8°C, 98.9°C) have been selected because they were initially used in the ASTM procedure for calculating the viscosity index of petroleum cuts (ASTM D 2270). 

This factor is the intermediate parameter employed in numerous calculational methods. For petroleum cuts obtained by distillation from the same crude oil, the Watson factor is generally constant when the boiling points are above 200°C. 

Characterization of Mixtures of Pure Hydrocarbons and Petroleum Fractions (Petroleum Cuts)... 

Simulated Distillation for Petroleum Cuts (ASTM D Z887)... 

Distillation simulated by gas chromatography is a reproducible method for analyzing a petroleum cut it is appiicabie for mixtures whose end point is less than 500°C and the boiling range is greater than 50°C. The results of this test are presented in the form of a curve showing temperature as a function of the weight per cent distilled equivalent to an atmospheric TBP. 

Each petroleum cut obtained by mixing the TBP distilled fractions (and thus characterized by the TBP cut points) is described by a coiiection of properties including the viscosity at two temperatures. 

The flash point measures the tendency of a petroleum material to form a flammable mixture with air. It is one of the properties to be considered when evaluating the flammability of a petroleum cut. 

The flash curve of a petroleum cut is defined as the curve that represents the temperature as a function of the volume fraction of vaporised liquid, the residual liquid being in equilibrium with the total vapor, at constant pressure. 

Coefficients for converting an ASTM D 86 curve to an atmospheric flash curve[ and an application for a petroleum cut whose standard specific gravity isl 0.746. ... 

The normalized distillation curves, TBP, ASTM D 86, and ASTM D 1160, provide a way to judge the quality of a fractionation performed on petroleum cuts. 

In the distillation units for producing petroleum cuts, the curves are determined in the laboratory from samples taken at regular intervals. 

Coefficients for converting a TBP curve into an ASTM D 86 curve and an example applied to a petroleum cut (Daubert s method). ... 

Petroleum solvents are relatively light petroleum cuts, in the C4 to C14 range, and have numerous applications in industry and agriculture. Their use is often related to their tendency to evaporate consequently, they are classified as a function of their boiling points. 

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