Plastics are extremely stable and decomposition in a landfill occurs over extended periods, with the introduction of more stringent environmental regulation, rising landfill costs and the drive towards a circular economy, there is an increasing need to redirect plastic waste from landfill/energy recovery towards enhanced recovery of the raw materials. The two main routes for the recycling of plastic waste are mechanical and feedstock. The most widespread approach to feedstock recycling is the pyrolysis (or cracking) of the plastic waste. However, this process requires high operating temperatures (typically 500°C – 900°C) with a subsequent large adiabatic temperature drop across the reactor (fixed bed or fluidised), which combined with catalyst deactivation, results in significant processing issues.
A more energy neutral option to catalytic cracking of plastics is that of hydrocracking, which offers the potential for the selective recovery of useful chemical fractions but is also is tolerant of the presence of heteroatoms such as bromine and chlorine.