Over the past few decades scientists have discovered that in the
absence of oxygen,plastic,which consist of long chain polymer
chain,can be fragmented at high temperature to form oligomers.
The term pyrolysis was used to refer to such process,although it
normally refers to thermochemical decomposition of organic materials at high temperature in the absence of oxygen.In some context,
the term “cracking” is used instead of pyrolysis. Nowadays ,it is a
common practice to differentiate thermal pyrolysis from catalytic
pyrolysis.The former refers to the decomposition of polymers due
to the application of heat alone,while the latter refers to the
processes where catalyst is utilized to alter the reaction mechanism
of pyrolysis,hence the products yield and composition.Some recent
studies focused on plastics waste pyrolysis using different processes
are shown in Table.