Petroleum oxygen content

In fractionation columns for petroleum products, where the oxygen content is restricted, higher temperatures can be used without excessive waste of the metal. 

Total Organic Carbon Formations with a significant TOC content greater than the petroleum hydrocarbon content, as with peat-rich soil, can compete with the hydrocarbon-degrading microbes for oxygen and nutrients. A representative sample should thus be analyzed for TOC if organic matter is observed in soil samples or borings. 

Oxygen is one of the five (C, H, N, O, and S) major elements in resids and asphalt, although the level rarely exceeds 1.5% by weight. Many petroleum products do not specify a particular oxygen content, but if the oxygen compounds are present as acidic compounds such a phenols (Ar-OH) and naphthenic acids (cycloalkyl-COOH), they are controlled in different specifications by a variety of tests. 

Most of the deposits formed in fuel and oil systems are rich in oxygen content. Oxygen in these deposits is not naturally occurring in the petroleum product, but typically comes from atmospheric oxygen. 

Just as a relationship exists between the various properties of petroleum with parameters such as depth of burial of the reservoir (Speight, 1999), similar relationships exist for the properties of coal (e.g., Solomon, 1981 Speight, 1994). Variations in hydrogen content with carbon content or oxygen content with carbon content and with each other have also been noted. However, it should be noted that many of the published reports cite the variation of analytical data or test results not with rank in the true sense of the word but with elemental carbon content that can only be approximately equated to rank. 

In Table I, a comparison is made of the elemental composition of typical asphaltenes from petroleum and coal liquids. This table shows the typical lower H/C ratio and higher oxygen content for the coal asphaltenes. Furthermore, the GPC molecular-weight distributions shown in Figure 7 illustrate the higher molecular-weight of petroleum asphaltenes as well as the wider molecular-weight distribution. 

Hydrodeoxygenation involves the removal of oxygen from various oxygen containing compounds in petroleum feedstocks. The oxygen content in petroleum crudes is very low, typically of the order of less than 0.1 wt%. Carboxylic acids and to a lesser extent phenols are found in low- and medium-boiling fractions. However, fuels derived from tar sands, shale oils, and coal have a substantial amount of oxygen compounds. These may include ethers, furan, carboxylic adds, and phenols. 

In order to sustain the combustion process, the quantity of air injected was cut down from 21,000-22,000 to 11,000-12,000 m /day. This reduction, in turn, resulted in a pressure drop to 12 kg/cm. As further consequence, in the course of four months the concentration of oxygen in the produced gases slowly increased while that of carbon dioxide decreased. Towards the end of July 1973, air injection was stopped, inasmuch as the oxygen content in the gases increased to 18-19% and that of carbon dioxide dropped to l.S - 2%. Obviously, by that time, only low temperature processes of petroleum oxidadon were taking place within the reservoir. 

The results show that addition of elemental sulfur inhibits mesophase formation. This effect is not as pronounced on materials of higher aromaticity and lower oxygen content such as petroleum pitch. We think that this is because the sulfur acts as a dehydrogenation agent and increases the condensation reaction rate to a point where it reduces fluidity and thus suppresses mesophase growth. 

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