Chemical recycling of waste is the decomposition of the polymers that make up waste through heat, chemicals or catalysts. It is also called tertiary or advanced recycling because with chemical or physical processes it aims at the almost complete recovery of monomers, oligomers or other compounds. Through these chemical processes, it is possible to obtain a great variety of raw materials ranging from monomers to mixtures of compounds, mainly hydrocarbons, which become a new source of chemicals or fuels. Products derived from chemical recycling have properties and qualities similar to those of virgin raw materials.
Chemical recycling has significant advantages over mechanical recycling which instead gives rise to secondary materials of lower value. Hence the great interest in this method of recovering plastic waste which highlights the potential of chemical recycling as a sustainability process in the polymer chemical industry.
How the chemical recycling of plastic takes place
The chemical industry and research teams are working on a wide variety of procedures and treatments for the recycling of plastic and rubber waste. The goal is to define chemical processes that are sustainable from an environmental point of view and compatible with an economy of scale. The procedures developed are mainly:
Chemical depolymerization. The starting monomers are produced by reaction with agents.
Gasification. The process is done with oxygen and/or steam to produce synthesis gas.
Thermal decomposition of polymers by heating in an inert atmosphere.
Catalytic cracking. The polymer chains are broken down with a catalyst that promotes cleavage reactions.
Hydrogenation. The polymer is degraded by the combined actions of heat, hydrogen and catalysts.