[GreenYes] Re: FW: [GreenYes] Re: Fwd: Plastic Bags - how much oil is wasted in producing them?

["Norm Ruttan" <normruttan@no.address>]

Well there, I put my foot in it again.

Ethylene is a product of steam cracking of hydrocarbons.

Ethylene is produced in the petrochemical industry via steam cracking.
In this process, gaseous or light liquid hydrocarbons are briefly
heated to 750-950 °C, causing numerous free radical reactions to
take place. Generally, in the course of these reactions, large
hydrocarbons break down in to smaller ones and saturated hydrocarbons
become unsaturated.

The result of this process is a complex mixture of hydrocarbons in
which ethylene is one of the principal components. The mixture is
separated by repeated compression and distillation.

Another process is catalytic cracking where it is used in oil
refineries to crack large hydrocarbon molecules into smaller ones. Use
of zeolite as a catalyst allows the cracking to be achieved at a lower
temperature. It is an important way of separating alkenes from alkanes
using a fractionating column.

Ethylene is used primarily as an intermediate in the manufacture of
other chemicals, especially plastics. Ethylene may be polymerized
directly to produce polyethylene (also called polyethene or polythene),
the world's most widely used plastic. Ethylene can be chlorinated to
produce ethylene dichloride (1,2-Dichloroethane), a precursor to the
plastic polyvinyl chloride, or combined with benzene to produce
ethylbenzene, which is used in the manufacture of polystyrene, another
important plastic.

Smaller amounts of ethylene are oxidized to produce chemicals including
ethylene oxide, ethanol, and polyvinyl acetate.

Ethylene is also a widely used refrigerant in commercial low
temperature systems due to the low boiling point.

Ethylene was once used as an inhaled anesthetic, but it has long since
been replaced in this role by nonflammable gases.

It has also been hypothesized that ethylene was the catalyst for
utterances of the oracle at Delphi in ancient Greece.