Chlorine removal from the pyrolysis of urban polyolefinic waste in a semi-batch reactor

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External organisations

  • Cranfield University
  • Recycling Technologies Ltd


The pyrolysis of urban chlorine-containing polyolefinic plastic waste with simultaneous retention of HCl is investigated. Different chemical removers based on sodium, calcium and zinc bases, and different adsorbents based on alumina or zeolites were used inside the reactor or in downstream hot filters, respectively, for chlorine removal and upgrading of pyrolysis oils. Initially, polyolefin waste (POW, containing a 98.5 wt% polyolefins) was thermogravimetrically pyrolyzed to determine its thermal behaviour. Subsequently, chemical removers were mixed with the POW which was pyrolyzed at 480 °C in a semi-batch reactor. The adsorbents were tested separately in hot filters (300 ± 20 °C) downstream of the pyrolysis reactor. After the pyrolysis, the resulting char containing the chemical removers and the absorbents in the hot filters were analysed by FTIR, CHN elemental analysis and ESEM-EDS to determine their respective chlorine contents. The highest chlorine retention was 23.8 wt% for chemical remover when used in direct contact with POW, while a zeolite used in the hot filter (gas streams) gave a chlorine retention of 65.6 wt%. The pyrolytic liquids consisted of mixtures of C7-C40 hydrocarbons made up of olefinic and aliphatic hydrocarbons with a very low presence of aromatics (estimated to be below 3 wt% by HPLC). In most cases, the chlorine removal processes resulted in waxier pyrolytic oils and with a higher degree of branching.

Bibliographic note

Funding Information: The funding to support this research was awarded by Innovate UK Energy Catalyst 4. D.T. is thankful for his contract funded by this Project. D.A.S.M and RT are thankful for the H2020 SME Innovation Programme and the European Commission for training in industrial innovation management. Cranfield University thanks the technical assistance received from the Recycling Technologies Ltd company throughout the project.


Original languageEnglish
Article number104920
JournalJournal of Environmental Chemical Engineering
Issue number1
Early online date11 Dec 2020
Publication statusPublished - Feb 2021


  • Chlorine removal, Dehydrochlorination of plastic waste, Hydrochloric acid removers, Plastic pyrolytic oils, Polyolefinic waste treatment, Pyrolysis of chlorinated plastic waste

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