Petroleum size characterization

Recently, petroleum residua have been studied extensively (I, 2) because of the increasing importance of heavier fuels. Both the asphaltene (pentane-insoluble) and maltene (pentane-soluble) components of residua are of interest, and since their properties overlap, a complete study of petroleum residua must consider both asphaltenes and maltenes. One area that has received considerable attention has been the size characterization of asphaltenes and maltenes (3, 4, 5). Size distribution data are useful both in understanding the fundamental chemistry of asphaltenes and maltenes and in observing the effects of various processes on residua sizes. 

This chapter first outlines the principles, methods, and basic techniques of particle size characterization used in the petroleum and chemical industries. The most common techniques and methods used in particle size characterization are then briefly discussed. This is followed by a summary of applicable particle size ranges for different methods, including size ranges of the most common particles found in petroleum applications. Emphasis is given to microscopy and scattering techniques and their applications in the petroleum industry. 

Scattering techniques are used heavily in the petroleum industry for particle and suspension size characterization. They are discussed in detail later in the chapter. 

To cover the scope of the different techniques used in particle size characterization, a survey was made of current literature. The results of this investigation are summarized in Figure 5 (2, 7, 14, 18). Also important is identification of the size ranges of most common particles found in the petroleum and chemical applications (2, 7, 14, 18) (Figure 6). Different types of industrially used particulate collecting equipment are summarized in Figure 7 (2, 7, 14, 15, 18). 

Lum, L.H. (2001) Particle Size Characterization, NIST Special Publication 960-1, National Institute of Standards and Technology, Washington, DC. Mikula, R.J. (1992) in Emulsions, Fundamentals and Applications in the Petroleum Industry (ed. L.L. Schramm), American Chemical Society, Washington, DC, pp. 79-129. 

There are several ways to classify or group various petroleum products. Refined oils are sometimes characterized by the approximate boiling-point range, which corresponds with the size (such as the number of carbon atoms) of the petroleum hydrocarbons in the refined oil ... 

The characterization of petroleum cracking catalysts, with which a third of the world s crude oil is processed, presents a formidable analytical challenge. The catalyst particles are in the form of microspheres of 60-70 micron average diameter which are themselves composites of up to five different micron and submicron sized phases. In refinery operation the catalysts are poisoned by trace concentrations of nickel, vanadium and other contaminant metals. Due to the replacement of a small portion of equilibrium catalyst each day (generally around 1% of the total reactor inventory) the catalyst particles in a reactor exist as a mixture of differing particle ages, poisoning levels and activities. 

Particle characterization is important in many petroleum and chemical applications. Therefore, it is essential to identify the main factors that control the behavior of particles in suspension. These factors include particle shape, size, size distribution, concentration, density, surface characteristics, and the dynamics of the suspension medium (7) (Figure 2). 

The aromatization of mixed-C4 hydrocarbons, prevalent by-products derived from petroleum refining processes, over HZSM-5 catalysts modified by both Zn and Ni cations via different impregnating methods has been systematically studied in two different sizes of reactors at various temperatures and space velocities of the feeds. The reaction mechanisms were discussed according to the liquid and gas product distributions. The acidity of the catalysts were also characterized using the frequency response (FR). 

The T2 distribution has applications as diverse as petroleum geology and bread making. It distribution has been applied in the petroleum industry for many years to characterize rock cores to obtain pore size distributions in well-logging operations. Rock cores from oil wells are filled with water or oil. The NMR CPMG echo train is acquired in a TD-NMR instrument and the T2 distribution is obtained. This is essentially a mirror image of pore size distribution, as water in small pores is more restricted it is less mobile (short T. Water in large pores has more freedom to move (long Tj). 

Fish, R.H., Komlenic, J.J., Wines, B.K. (1984) Characterization and comparison of vanadyl and nickel compounds in heavy crude petroleum and asphaltenes by reverse phase and size-exclusion liquid chromatography/graphite furnace atomic absorption spectrometry. Anal. Chem. 56, 2452-24. ... 

Abstract Thermal analytical methods such as differential scanning calorimetry (DSC) have been successfully applied to neat petrodiesel and engine oils in the last 25 years. This chapter shows how DSC and P-DSC (pressurized DSC) techniques can be used to compare, characterize, and predict some properties of alternative non-petroleum fuels, such as cold flow behavior and oxidative stability. These two properties are extremely important with respect to the operability, transport, and long-term storage of biodiesel fuel. It is shown that the quantity of unsaturated fatty acids in the fuel composition has an important impact on both properties. In addition, it is shown that the impact of fuel additives on the oxidative stability or the cold flow behavior of biodiesel can be studied by means of DSC and P-DSC techniques. Thermomicroscopy can also be used to study the cold flow behavior of biodiesel, giving information on the size and the morphology of crystals formed at low temperature. 

The current contribution describes a hydrotreatment catalysts preparation method for different petroleum distillates - gasoline and vacuum gas oil (VGO). Since S- and N- containing compounds of these distillates characterized with a different molecule size, the nanoparticles of active phase have to be arranged in the pores with relatively small sizes for gasohne and with a large size for vacuum gas oil. The key factor in obtaining such catalysts is the size of the bimetallic complexes used for the catalysts preparation. Whereas the molecule size of the complex that will be supported determines in what pores the active sites will be arranged. 

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