ABSTRACT
Petroleum is a word that comes from the Greek word petros (rock) and Latin word oleum or Greek elaion (oil), so petroleum means “rock oil.” Petroleum is the most important source of energy and one of the main chemical industries in the world, and it is expected to remain so over the next decades. Petroleum is a complex mixture of different organic compounds or hydrocarbons. These compounds are formed mainly from carbon and hydrogen elements with different length of chain or number of aromatic rings going from light gases to heavy residues. Other elements are present in lower proportion such as sulfur, oxygen, and nitrogen, or metals to a lower extent. Petroleum hydrocarbons, a term used to refer to crude oil and the rened products from it, are usually obtained from distillation of crude oil. The nal product composition depends on the crude oil source and the rening process used to produce it, so it varies, not only among the product types, but also within each product type.
