<%@LANGUAGE="JAVASCRIPT" CODEPAGE="1252"%> Sustainable development

Feedstock recycling

The raw materials that go onto the production of PVC are called 'feedstocks'.

Some products contain different materials bonded together. These composite materials cannot be easily separated. To recycle them, they are first chemically broken down into their basic compounds. These can then be used as the raw materials for the production of new polymers or in other processes.

Feedstock recycling helps to turn PVC manufacture into a 'closed loop process'.

PVC polymer

PVC is a polymer that contains many useful molecules and atoms.

PVC pyrolysis

Useful feedstocks can be recovered from PVC waste.

Several different processes are being developed. They break the PVC down by using high temperatures and pressures.

Roll over the temperature scale to see the
molecules produced at different temperatures.

Pyrolysis temperature scale

1400 - 1600^oC

These high temperatures turn the PVC into gases.

Hydrogen chloride is used to regenerate chlorine for PVC production.
Hydrogen is used as a fuel to generate energy.
Carbon monoxide is used in other chemical processes.

Hydrogen Chloride
(HCl)

Hydrogen
(H₂)

Carbon monoxide
(CO)

Ash and slag are deposited in the rotary kiln. This can recycled for use in building materials.

950 - 1100^oC

High temperatures causes the PVC waste to burn.

This 'pyrolysis' in a rotary kiln results in the formation of Hydrogen Chloride which can be processed to regenerate chlorine for the production of new vinyl chloride monomer (VCM).

Hydrogen Chloride
(HCl)

Ash and slag are left over in the rotary kiln. This can recycled for use in building materials.

250 - 600^oC

Adding Sodium hydroxide (NaOH) and heating to 250^oC splits off chlorine atoms from the PVC waste. This is called hydrolysis.

It forms sodium chloride, or salt (NaCl) which can be used in many other processes such as generating chlorine for the production of new PVC.

Sodium Chloride
(NaCl)

At 600^oC, the PVC chains break down. This releases useful hydrocarbons that can be used instead of oil or gas to make new plastics.

Hydrocarbons