Additives for automotive fuels and lubricants

Additives are critical to the manufacture and use of automotive field and lubricants. They are used in petroleum recovery (drilling additives) (1) refining (refinery chemicals) (2), and in formulating fuel and lubricants. This article explains the role of additives as performance chemicals in fuels and lubricants. The paper comprises two sections refining and additives. The first section 1 describes the manufacture of fuels and lubricant base stocks from petroleum and the second section describes the chemistry and function of additives. Petroleum, or crude oil, is a complex mixture that contains many inorganic and organic compounds. Organic compounds present in petroleum belong to three general classes: hydrocarbons, heterocyclics, and asphaltenes (3). Hydrocarbons, the major constituent, are compounds that contain carbon and hydrogen only. These compounds can be further classified into alkanes, alkenes, alicyclics, and aromatics. Alkanes, also known as paraffins, are compounds with saturated linear or branched structures. They do not contain cyclic structures or rings. Alkenes, also known as olefins, are unsaturated (contain double bonds) molecules that do not occur to a great extent in crude petroleum but result from cracking or dehydrogenation during certain refining processes. Alicyclics, also known as naphthenes, are saturated compounds that contain cyclic structures or rings. Aromatics are compounds that contain rings with alternating single and double bonds. When present in crude oil, they are primarily based on the six-membered benzene ring. In crude petroleum, most compounds have composite structures; that is, they contain linens or branched hydrocarbon chains and rings in the same structure. Heterocyclics are compounds that in addition to carbon and hydrogen contain sulfur and nitrogen in a ring. Asphaltenes, present in the smallest amount, are very high molecular weight compounds with heterocyclic and aromatic structures.