Sulfur Content of Crude Oils

Following carbon and hydrogen, sulfur is the third most abundant element found in crude oil. The average sulfur content of crude oil is approximately 6500 ppm but can be identified at concentrations >5 wt% or more. 

A critical prerequisite for the use of synthesis gas or CO in most reactions catalyzed by transition metals is that sulfur compounds, such as H2S, thiols, or COS, derived from the sulfur content of crude oil or coal must first be removed (hydrodesulfurization, see Section 21-4). 

Sulfur contents of crude oils have been reported to vary from less than 0.1 to 7.5 wt. % (58), but values from 0.2 to 2.5% are more typical (319). A survey of 330 U.S. crude oils showed the following breakdown according to sulfur content (303) ... 

TABLE 1—Typical sulfur content of crude oils from some giant oil fields [1],... 

RG. 5—The relationship of the organic nitrogen and organic sulfur content of crude oil on carbon steel corrosion rate in crude oil/brine mixtures [73. (4% NaCI brine at. 2 mPa CO2 pressure and 85 C.)... 

Figure 5.1.23 Sulfur content of crude oils and of distillation fractions.

Average sulfur content of crude oils refined in US, wt% based on sulfur 0.89 1.13 1.42... 

Nelson, Thery, and Cordero, Relationship between Sulfur Content of Crude Oils and the Sulfur Content of Conventional Refinery Products, Proc. Fourth World Pet, ConffT-y see. V/A, Rome, Jime, 1955. 

FCC feedstocks contain sulfur in the form of organic-sulfur compounds such as mercaptan, sulfide, and thiophenes. Frequently, as the residue content of crude oil increases, so does the sulfur content (Table 2-5). Total sulfur in FCC feed is determined by the wavelength dispersive x-ray fluorescence spectrometry method (ASTM D-2622), The results are expressed as elemental sulfur. 

Sulfur content in crude oils and natural bitumens varies from less than 0.05 to more than 14 weight percent, but few commercially produced crude oils exceed 4% sulfur. Tissot and Welte (25) show a frequency distribution of crude oils based on over 9,000 samples and report the average sulfur content as 0.65%. The distribution is clearly bimodal with a minimum at about 1% sulfur. Oils with less than 1% sulfur are classified as low-sulfur, and those above 1% as high-sulfur. In general, high-sulfur oils are derived from carbonate or carbonate-evaporite rock sequences whereas low-sulfur oils are derived largely from clay-rich clastic sequences f25-26.28-29). 

Unrefined canola oil is said to contain low levels of sulfur-containing fatty acids, resulting in the presence of sulfur in the oil in the stable form of triglycerides. These triglycerides resist refining procedures. See Table II for the sulfur content of crude, refined, and deodorized canola oils. ... 

Organic sulfur compounds (e.g., mercaptans, sulfides, polysulfides, thiophenes) are present in petroleum products to a greater or lesser extent depending on the crude oil origin and the refinery treatment. The sulfur content of fuel oil (ASTM D-396) can be determined by a variety of methods (ASTM D-129,ASTM D-1552, ASTM D-2622, ASTM D-4294, IP 61, IP 63), with mercaptan sulfur in cracked stocks being particularly necessary for evaluation (ASTM D-3227, IP 342). 

Determination of Sulfur Content in Crude Oil Using On-Line X-ray Transmission Technology... 

The X-ray Transmission technique is a viable method for the determination of sulfur content in crude oil. 

Typical sul r compounds present in cmde oils are shown in Figure 5.1.22. The S-content of crude oils and distillation fractions varies (Figure 5.1.23). As a general trend, heavy crude contains more sulfur than a lighter one. The combustion of S-containing fuels produces SO2. Thus the S-compounds are converted, and finally end up as elemental sulfur. 

Applications to neutron activation analysis constitute another important use of Cf neutron sources. Neutron capture in many elements forms radioactive species that then decay with highly characteristic gamma-ray emissions. This analytical procedure is very sensitive and specific, and is widely used for the analysis of trace elements. Neutron activation finds use in uranium borehole logging to make accurate determinations of the uranium concentrations in boreholes as little as 100 parts per million of UaOg can be detected by this procedure. Other industrial uses for Cf sources are in the continuous monitoring of the sulfur and ash content of coal on a moving conveyor belt at the rate of SO tons per hour. Batch analysis of the vanadium content of crude oil is still another application of neutron activation analysis. 

High temperature sulfidation can be found in primary, secondary and even downstream chemical processing units. Therefore, corrosion attack associated with sulfur is one of the major corrosion problems and can occur in the whole refining process. The total sulfur content in crude oils is not directly correlated with their corrosivity. Actually the corrosivity is mainly dependent... 

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