Virgin polymers via pyrolysis – A review of heteroatom removal options

Abstract

This review is dedicated to the removal of heteroatoms from plastic pyrolysis liquid products for use in the petrochemical industry. The chapters are devoted to removing individual groups of heteroatoms and summarizing the current scientific knowledge on the subject. Attention is given to the possibilities of heteroatom removal at all stages of the recycling process except sorting. Most of the findings in this area relates to the halogen removal, where high efficiencies can be achieved already in the pyrolysis process. In contrast, the removal of other heteroatoms has mainly been studied in the liquid product, usually in a hydrogen atmosphere and in the presence of a catalyst. It seems economically feasible to remove the heteroatoms as early as possible in the recycling process. This can be achieved in part by washing the waste plastic in water, which can remove a large proportion of the heteroatoms present as impurities. The work highlights the need for comprehensive mapping of heteroatoms in products and, in many cases, the need for more data regarding their removal. Finally, conclusions are drawn for further research in this area.