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— Steam – high temperature steam (1500 degrees Fahrenheit
/ 816 degrees Celsius) is used to break ethane, butane and naptha
into ethylene and benzene, which are used to manufacture
chemicals.
— Visbreaking – residual from the distillation tower is
heated (900 degrees Fahrenheit / 482 degrees Celsius), cooled with
gas oil and rapidly burned (flashed) in a distillation tower. This
process reduces the viscosity of heavy weight oils and produces
tar.
— Coking – residual from the distillation tower is heated to
temperatures above 900 degrees Fahrenheit / 482 degrees Celsius
until it cracks into heavy oil, gasoline and naphtha. When the
process is done, a heavy, almost pure carbon residue is left (coke);
the coke is cleaned from the cokers and sold. Photo courtesy
Phillips Petroleum Company Catalysts used in catalytic cracking
or reforming
Catalytic – uses a catalyst to speed up the cracking reaction.
Catalysts include zeolite, aluminum hydrosilicate, bauxite and
silica-alumina.
— Fluid catalytic cracking – a hot, fluid catalyst (1000
degrees Fahrenheit / 538 degrees Celsius) cracks heavy gas oil into
diesel oils and gasoline.
— Hydro cracking – similar to fluid catalytic cracking, but
uses a different catalyst, lower temperatures, higher pressure, and
hydrogen gas. It takes heavy oil and cracks it into gasoline and
kerosene (jet fuel).
After various hydrocarbons are cracked into smaller
hydrocarbons, the products go through another fractional
distillation column to separate them.

Unification

Sometimes, you need to combine smaller hydrocarbons to
make larger ones – this process is called unification. The major

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