Crude oil chemistry

The last chapter (i.e. chapter 2) of Part I deals with modem analytical methods used in crude oil chemistry. Modern and classical methods of petroleum and petroleum products characterization are explained. This chapter is an essential chapter for present and potential crude oil chemists since analytical chemistry constitutes an important part of crude oil chemistry. Besides, crude oil products have so many special properties that are important for the industry. The need to determine these properties gives rise to the very many analytical methods used in petroleum chemistry. 

Special properties of asphaltenes include the tendency to associate, high molecular weight and paramagnetism. All these properties make asphaltenes very difficult to analyze or investigate. This is why approximately since the 1970s, asphaltenes chemistry exists as a separate science independent from crude oil chemistry. In part four of this book, some problems that arise in asphaltenes studies will be discussed. 

It is obvious from the stated requirements that there are a lot of materials that can be analyzed by gas chromatography. However, the requirement that the material be gaseous or vapor at the column temperature provides a restriction in the crude oil compounds that can be analyzed. Actually, with the requirement for the boiling temperature to be under 350°C, it is only possible to analyze the light fractions from petroleum such as gasoline, kerosene and diesel. However, these fractions are very important for their industrial use as fuels. This makes gas chromatography one of the most popular analysis techniques in crude oil chemistry. 

The next possible carrier gas is nitrogen. This is probably the cheapest and least dangerous carrier gas. However, it must be noted that nitrogen is also used as an inert atmosphere in many experiments in crude oil chemistry. This means that gas coming to the analysis contains nitrogen. The analysis of nitrogen in the gas mixture would be impossible if the carrier gas is the same as one of the components of the sample mixture. 

Infrared red spectroscopy is based on the ability of the substances to absorb light of a given wavelength. Infrared spectroscopy is today one of the most important spectral analytical methods in the crude oil chemistry, because of its high information content and the variety of possibilities for sample preparation. 

The first step in carrying out an infrared spectroscopic analysis is the preparation of the sample. The types of samples analyzed by infrared spectroscopy in crude oil chemistry are solid or liquid samples. 

Fluoremetry is especially useful for the determination of condensed aromatic and heteroatomic compounds in crude oil and its products. The use of fluoremetry in crude oil chemistry is presently so highly developed that already there is a special classification of types of fluoremetry typical for crude oil chemists. These are the qualitative, visible and quantitative methods widely used by crude oil chemists. 

More detailed descriptions of techniques and methods of fluoremetry for crude oil chemistry can be found in references 78 and 79 given at the end of this chapter. 

Both methods are used for the determination of the metal content. The determination of the concentrations of heavy metals in crude oil and its products is an important topic in environmental chemistry. Heavy metals are always present in crude oil, especially in the heavy fractions such as residual fuel. The control of the concentration of heavy metals in such fuels is very important for ecological monitoring in crude oil chemistry. More about the methods, techniques and modern research results made by atomic absorption spectroscopy and atomic emission spectroscopy can be found in references 80-82 shown at the end of this chapter. 

X-ray spectroscopy can be classified in the same manner as every other type of spectral analysis into absorption and emission spectroscopy. However, the most popular method of x-ray spectroscopy in crude oil chemistry is the emission spectroscopy, also called x-ray fluorescence spectroscopy. The effect used by this type of spectral analysis is the same as was described for fluorescence analysis. However, x-rays are used for this analysis instead of the ultraviolet radiation used for fluorescence analysis. 

The x-ray fluorescence analysis is used by crude oil chemists as an express method for the determination of the metal contents in crude oil and its products. This is very important because the metals in crude oil are poisons for cracking catalysts, and are also undesired in the fuels, since they lead to environmental pollution. All the elements with atomic number greater than eleven in the periodic table can be analyzed by x-ray fluorescence spectrometry. An important task of this method in crude oil chemistry is the determination of heteroatoms such as sulfur, oxygen, and nitrogen. Frequently, x-ray fluorescence spectrometry is used to verify the presence of certain additives in oils. 

Reffactometry is the last analysis method discussed in this part of the book. However, some more analysis methods can be found in chapter 8 of this book. The reason to describe these analysis methods in another chapter is the high importance attached to these methods for asphaltene chemistry, which is an important part of crude oil chemistry. 

It would be appropriate to say at this point that this chapter deals more with crude oil economy than with crude oil chemistry. However, the aim of this chapter is to show the importance of crude oil chemistry not only for crude oil chemists, but also for all of mankind. Almost everything around us is derived from crude oil. This includes plastic parts, car fuel, jet fuel, oils, and even asphalt on the road these are all made from petroleum. It is hard to imagine what modern life would look like without these items, which began their existence from the oil well. 

The foregoing discussion explains why this chapter deserves a place in this book. It helps us to understand the importance of crude oil chemistry for the people making decisions about the future of petroleum education, for example. This chapter shows new impressive sides of this branch of study. 

The chemistry of asphaltenes is very complicated and it is the least studied field of crude oil chemistry. Because of the complexity of asphaltenes structure, there is no information about the exact chemical structure of an asphaltene molecule. It is natural that only the average asphaletene molecular is possible as given in the literature. The use of such a chemical structure (i.e. average molecular structure) for the asphaltene molecule is warranted because of the wide molecular weight range and the diversity of chemical groups in the structure of asphaltenes. 

Sigurdsson, H. (1982) Volcanic pollution and climate the 1783 Laki eruption. Transactions of the American Geophysical Union (EOS) 63, 601-602 Sillen, L. G. (1967) The ocean as a chemical system. Science 156, 1189-1197 Simanzhenkov, V. and R. Idem (2003) Crude oil chemistry. Marcel Dekker Inc., New York,... 

Figure 10. Potential tasks for a Ball-Bearing on crude oil chemistry...

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