Petroleum Thermal Behavior

Analytical methods describing the thermal behavior of substances during programmed temperature changes, like thermogravimetry, differential thermoanalysis, or differential scanning calorimetry are old methods, which were applied at first to problems of inorganic chemistry, mainly to minerals. The analysis of petroleum and petroleum products has been mentioned relatively late. In the literature survey by Weselowski [1-1] the first citation dates from 1958. Also, the oldest citation in the research report by Kettrup and Ohrbach [1-2] dates from 1965. 

Thermogravimetry is well-suited to describe the distillative, cracking, and oxidative behavior of crudes and petroleum products. The thermal behavior may be described... 

Furthermore, paraffins can be mixed in order to realize desired temperature ranges in which a phase change takes place. These products are relatively inexpensive (often byproducts of petroleum refining), hydrophobic, nontoxic, and noncorrosive. In addition, their thermal behavior also remains stable under permanent use. 

During the last two decades, the DTA-EGD-GC on-line coupled simultaneous apparatus has been applied in the following fields solid catalysts [77-79], anti-oxidation additives in petroleum [80], thermal characteristics of coal [81-83], mineralogy [60, 84-87], organometallic chemistry [88-90], polymer chemistry [91], pharmaceutical chemistry [92], environmental protection chemistry and the thermal behavior of all kinds of chemical compounds [62, 63]. Numerous DTA-EGD-GC curves are shown in Chapter 13. 

The PCN monomer was prepared by reaction of cyanamide with phenylisocyanate in alkaline solution at 15-18°C according to the literature [40]. The crude white powdered product was purified by recrystallization from an acetone-petroleum ether mixed solvent. The resulting colorless fine needles of phenylcarbamidonitrile melted at 134-136°C. Figure 5 shows its thermal behavior in differential scanning calorimetry (DSC, Dupout 1090) a sharp endothermic melting point peak appears... 

Carbon black Finely divided carbon made by incomplete combustion or decomposition of natural gas or petroleum-based oils in different types of equipment. According to the process and raw material used, it can be furnace (e.g., HAF), thermal (e.g., MT), or channel carbon black (e.g., EPC), each having different characteristics, such as particle size, structure, and morphology. The addition of different types of carbon blacks to rubber compounds results in different processing behavior and vulcanizate properties. 

For present purposes discussion of equilibrium phenomena is divided into the fields of phase equilibria, volumetric behavior, thermal properties, and surface characteristics. The subject matter is limited to a number of the components and their mixtures which are found in petroleum. The phenomena are restricted to those involving properties in which time does not enter as a variable. The elimination of time follows from the basic characteristic of an equilibrium state in which the properties of the system are invariant. 

The stability of the products from coal-derived syncrudes must be examined carefully. Many unique compounds are present in these syncrudes peri-condensed aromatics and naphthenes, oxygen compounds, and asphaltene-like hydrocabons. Traces of these compounds may remain in the hydrotreated product and their effect on jet, thermal, and oxidation stabilities cannot be predicted from the behavior of petroleum products. 

Some of the inconsistencies in the research are probably due to variation in petroleum cokes. It is generally conceded that the coker is the "garbage can" of the refinery and as such it seldom sees an identical charge from day to day. Cokes with virtually identical chemical analyses can exhibit markedly different behavior when subjected to identical thermal treatments. 

M. F. Ali, and M. N. Siddiqui, Thermal and catalytic decomposition behavior of PVC mixed plastic waste with petroleum residue. Journal of Analytical and Applied Pyrolysis, 74, 282-289, (2005). 

Somerton, W.H., 1992. Thermal properties and temperature-related behavior of rock/fluid systems. Developments in Petroleum Science 37. Elsevier, Amsterdam, 257 pp. 

The pour point of petroleum is an index of the lowest temperature at which the crude oil will flow under specified conditions. The maximum and minimum pour point temperatures provide a temperature window where petroleum, depending on its thermal history, might appear in the liquid as well as the solid state. The pour point data can be used to supplement other measurements of cold flow behavior, and the data are particularly useful for the screening of the effect of wax interaction modifiers on the flow behavior of petroleum. 

Petroleum lubricating oils are sometimes characterized by their density. As will be seen when we come to the examination of chemical structures in lubricating oils later in this chapter, density is associated with structural type. Paraffinic oils are lower in density than naphthenic or aromatic oils. Since paraffinic oils show more desirable viscosity-temperature behavior and better thermal stability than naphthenic oils, in the past density was widely used as an easily measured indicator of oil quality. With the development of additives to improve viscosity and thermal stability behavior, classification of oils by their density ratings has lost much of its former importance. 

Electrothermal atomic absorption represents a suitable instrumental technique for the analysis of elements in petroleum products [1-5]. The technique shows very low detection limits, similar to or even better than those found for other spectroscopic techniques, such as Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES) [6] and ICP-Mass Spectrometry (ICP-MS) [7-12]. Some problems were evidenced in the use of ETAAS when elements like Ni [3] and Pb [13] are analyzed, due to the different behavior of organo-metallic species during the thermal treatment of standards and samples. 

Under these circumstances, it seems reasonable to study the thermal reactions such as boiling, pyrolysis, and the oxidation behavior of defined model substances first, in order to understand the behavior of petroleum and its main products and to draw some analogous conclusions. 

The application of thermoanalytical methods to the investigation of the kinetics of pyrolysis and oxidation processes of heavy petroleum components representing multi-component systems proved to be successful. Whereas the ASTM E 698-79 and the Flynn and Wall methods can be applied relatively uncritically, the interpretation of the data from the McCarty and Green method requires a solid knowledge of the thermal and oxidative behavior of the samples. The attempt to use the evaluation according to Borchardt and Daniels proved not to be successful for pyrolysis nor for oxidation reactions. Most of the... 

In summary, it has been assumed, on the basis of the behavior of the thermal decomposition of polynuclear aromatic systems, that coal must also consist of large polynuclear aromatic systems (Chapter 10). Be that as it may, such assumptions are highly speculative and, to say the least, somewhat lacking in caution. As an example, similar lines of thought have been applied to structural assumptions about petroleum asphaltene constituents when it is known from other pyrolysis studies that smaller, but polar, systems can produce as much thermal coke as the larger nonpolar highly condensed systems (Speight, 2007). 

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