Crude origin

Carb.) depend on the crude origin and the processing severity. Metals, having been 90 to 95% retained on the catalysts, are found in low quantities in residues. 

Naphtha from atmospheric distillation is characterized by an absence of olefinic compounds. Its main constituents are straight and branched-chain paraffins, cycloparaffms (naphthenes), and aromatics, and the ratios of these components are mainly a function of the crude origin. 

Depending on the crude origin, already the introduction of dirty wash oil can have a significant impact on the metal content of the FCC feed and hence the catalyst. Several deasphalting processes open up the possibility to cut deeper, but also more selective in terms of asphalthene and metal content into the resid. 

Crude oil contains a number of metallic elements which are of interest either due to the undesirable effects they cause in the refining process or as an indication of the origin of the oil. The concentration levels encountered will vary with the type of crude oil. Crudes originating from different oil fields may vary markedly in trace-metal content. Also some crude oils will become contaminated in transport from the oil well to the refinery by, for example, pipeline material or seawater. The levels of such metals as Ni, V and Na must be carefully controlled in order to reduce production problems such as plant corrosion or catalyst poisoning. 

Petroleum asphalts, compared to native asphalts, are organic with only trace amounts of inorganic materials. They derive their characteristics from the nature of their crude origins with some variation possible by choice of manufacturing process. Although there are a number of refineries or refinery units whose prime function is to produce asphalt, petroleum asphalt is primarily a product of integrated refineries (Fig. 1). Crudes may be selected for these refineries for a variety of other product requirements and the asphalt (or residuum) produced may vary somewhat in characteristics from one refinery-crude system to another and even by cut-point (Table 2) and asphalt content (Fig. 2) (5,6). The approximate asphalt yields (%) from various cmde oils are as follows ... 

Sulfitr and nitrogen contents in 550°C uacaum residues according to crude oil origin. Source Total. 

Their chemical compositions are very complex and depend essentially on their age, that is, the phase of development of the kerogene, regardless of the origin of the crude (Speight, 1991) (see Chapter 1). 

Crude oil name Country of origin Specific gravity... 

Sulfur comes mainly from the decomposition of organic matter, and one observes that with the passage of time and of gradual settling of material into strata, the crude oils lose their sulfur in the form of H2S that appears in the associated gas, a small portion stays with the liquid. Another possible origin of H2S is the reduction of sulfates by hydrogen by bacterial action of the type desulforibrio desulfuricans (Equation 8.1) ... 

Refining has the function of transforming crude oil from various origins into a set of refined products in accordance with precise specifications and in quantities corresponding as closely as possible to the market requirements. 

An alternative approximation scheme, also proposed by Bom and Oppenheimer [5-7], employed the straightforward perturbation method. To tell the difference between these two different BO approximation, we call the latter the crude BOA (CBOA). A main purpose of this chapter is to study the original BO approximation, which is often referred to as the crude BO approximation and to develop this approximation into a practical method for computing potential energy suifaces of molecules. 

Recrystallisation. The process of purification by recrystallisation is undoubtedly the most frequent operation in practical organic chemistry, and it is one which, when cleanly and efficiently performed, should give great pleasure to the chemist, particularly if the original crude material is in a very impure and filthy condition. Yet no operation is carried out so badly, wastefully (and thoughtlessly) by students in general, not only by elementary students, but often by research students of several years experience. The student who intends later to do advanced work must master the process, for unless he can choose a suitable solvent and then successfully recrystallise often minute quantities of material, he will frequently find his work completely arrested. 

If the mother-liquor from the crude product (together with the washings) is concentrated to nearly half its original volume by gentle distillation, and is then cooled and seeded with a trace of the first crop, a second and less pure crop of the a-methylglucoside is obtained. This should be purified by recrystallisation from the mother-liquor obtained from the recrystallisation of the first crop, and then if necessary recrystallised a second time from a small quantity of fresh methanol. Yield of second crop, about... 

The residue in the flask may be mixed with the aqueous layer of the first distillate, 40 g. of isopropyl alcohol added, and the slow distillation repeated. The yield of crude isopropyl bromide in the second distillation is only slightly less than that obtained in the original preparation. Subsequently most of the residual hydrobromic acid may be recovered by distillation as the constant boiling point acid (126°). 

Concentrate the combined filtrate and washings (W) to about half the original volume, and pour it into sUghtly more than the calculated amount of dilute hydrochloric acid (use a mixture of 30 ml. of concentrated hydrochloric acid and 30 ml. of ice-water) then add about 300 ml. of water. Collect the active aec.-octyl hydrogen phthalate (crude lA) as above (5). The weight of the air-dried ester is about half that of the dl-ester originally used (7). 

Method 2. Place 90 g. of sodium benzenesulphonate (Section IV,29) (previously dried at 130-140° for 3 hours) and 50 g. of powdered phosphorus pentachloride (1) in a 500 ml. round-bottomed flask furnished with a reflux condenser heat the mixture in an oil bath at 170-180° for 12-15 hours. Every 3 hours remove the flask from the oil bath, allow to cool for 15-20 minutes, stopper and shake thoroughly until the mass becomes pasty. At the end of the heating period, allow the reaction mixture to cool. Pour on to 1 kilo of crushed ice. Extract the crude benzenesulphonyl chloride with 150 ml. of carbon tetrachloride and the aqueous layer with 75 ml. of the same solvent. Remove the solvent under atmospheric pressure and proceed as in Method 1. The yield is about 170 g., but depends upon the purity of the original sodium benzenesulphonate. 

Method 2. Place a mixture of 126-5 g. of benzyl chloride, 76 g. of thiourea and loO ml. of rectified spirit in a 500 ml. round-bottomed flask fitted with a reflux condenser. Warm on a water bath. A sudden exothermic reaction soon occurs and aU the thiourea passes into solution. Reflux the resulting yellow solution for 30 minutes and then cool in ice. Filter off the white crystals and dry in the air upon filter paper. Concentrate the filtrate to half its original volume and thus obtain a further small crop of crystals. The yield of crude hydrochloric acid as in Method 1 the m.p. is raised to 150°, although on some occasions the form, m.p. 175°, separates. 

Osmium s voice In the original patent a continuous, 27 hours extraction with hot toluene was used. This is very impractical. I recommend the following after extraction and removal of the ex traction solvent, dissolve the crude product in 400 - 450 ml hot toluene, put that solution in a beaker and cool it for at least 2 hours in an ice bath. Filter the precipitated product, wash with about 100 ml ice-cold toluene ahd dry at 70°C or in a desiccator to constant weight. Mp. 132.5-134.0°C.]... 

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