Nitrogen-Containing Compounds from Petroleum

Molybdenum(VI) oxide is used in catalyst compositions to carry out desulfurization of petroleum feedstocks and to remove nitrogen-containing compounds from petroleum fractions. Other uses of this oxide include preparation of various molybdate salts and as reagents for chemical analyses. 

Nitrogen-Containing Compounds from Petroleum and Natural Gas... 

Unisol A process for extracting organic sulfur and nitrogen compounds from petroleum fractions by solvent extraction with aqueous sodium or potassium hydroxide containing... 

The feed hydrocarbons, which come from the FCC or from the etherification unit of a petroleum refinery, usually have to be treated before entering the alkylation unit. They contain water, butadienes, and sulfur- and nitrogen-containing compounds and—when coming from an etherification unit—traces of oxygenates. 

Nitrogen-containing compounds in shale oil were concentrated by FeCl3-clay complexation chromatography. Similarly the nitrogen compounds were also investigated from petroleum as well as coal liquids. 

Nitrogen-containing compounds are obtained from petroleum and natural gas primarily by three processes—i.e., nitration direct amination, and direct cyanidation of hydrocarbons. The author has listed review articles containing numerous references and the subject headings for searching indexes, in order to give the individual insight into the approach necessary in this field. 

As we have seen, the primary sources of hydrocarbons are the fossil fuels petroleum and coal. Aliphatic hydrocarbons are obtained primarily from petroleum, which is a mixture of aliphatic and aromatic hydrocarbons, together with some organic compounds containing sulfur and nitrogen (Fig. 18.15). Coal is another major source of aromatic hydrocarbons. 

In addition to hydrocarbons, petroleum also contains compounds that consist of nitrogen, oxygen, and sulfur (in the minority) as well as trace amounts of metals such as vanadium, nickel, iron, and copper. Porphyrins, the major organometaUic compounds present in petroleum, are large, complex cyclic carbon structures derived from chlorophyll and characterized by the ability to contain a central metal atom (trace metals are commonly found within these compounds). 

From a chemical standpoint petroleum is an extremely complex mixture of hydrocarbon compounds, usually with minor amounts of nitrogen-, oxygen-, and sulfur-containing compounds as well as trace amounts of metal-containing compounds (Chapter 3). 

Alkanes are derived mostly from petroleum and petroleum by-products. Petroleum, often called crude oil, is pumped from wells that reach into pockets containing the remains of prehistoric plants. The principal constituents of crude oil are alkanes, some aromatics, and some undesirable compounds containing sulfur and nitrogen. The composition of petroleum and the amounts of contaminants vary from one source to another, and a refinery must be carefully adjusted to process a particular type of crude oil. Because of their different qualities, different prices are paid for light Arabian crude, West Texas crude, and other classes of crude petroleum. 

Today, benzene and other aromatic and aliphatic hydrocarbons are obtained from fossil fuels, which formed over millions of years from the remains of living things. The main source of these compounds is petroleum, a complex mixture of alkanes, some aromatic hydrocarbons, and organic compounds containing sulfur or nitrogen atoms. 

Although crude petroleum contains small amounts of oxygen, nitrogen, and sulfur, its major constituents are hydrocarbons—compounds of carbon and hydrogen. Isolating individual hydrocarbon substances from petroleum mixtures is an industrial process of central importance. Moreover, it provides a fascinating story that illustrates how the structures of molecules determines the properties of substances and the behavior of those substances in particular processes. The next three sections present a brief introduction to this story, emphasizing the structure-property correlations. 

---