Hydrotreating in Petroleum Chemistry

Crude oil is probably the most important feedstock in the modern world, not only for fuel production but also as a starting material for making commodity chemicals. Although mainly composed of hydrocarbons, crude oil contains variable amounts of compounds containing heteroatoms (of the order of 1 % S, 

25% N and ppm levels of various metals such as vanadium and nickel). These elements are harmful to the environment, as upon combustion they produce SOx and NOx gases (responsible for acid rain), and to the chemical industry, as these molecules can poison the catalysts needed for the subsequent cracking and reforming operations (see Box 2, and Chapter 1, Section 1.2.1). 

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