Entrained Flow Gasification of Polypropylene Pyrolysis Oil

Area of Science:

• Chemical Engineering
• Sustainable Chemistry
• Waste Valorization

Background:

• Petrochemical production traditionally relies on virgin fossil fuels.
• Circular economy principles encourage utilizing waste plastics as feedstock.
• Entrained flow gasifiers offer high syngas quality but struggle with direct plastic feeding.

Purpose of the Study:

• To investigate a two-step process for converting polypropylene waste into syngas.
• To overcome challenges of feeding plastic waste into entrained flow gasifiers.
• To characterize products and quantify yields of the integrated pyrolysis-gasification system.

Main Methods:

• Polypropylene was pre-treated via pyrolysis to generate a liquid intermediate.
• The liquid intermediate was then fed into an entrained flow gasifier.
• Products from both pyrolysis and gasification steps were thoroughly characterized.
• Product yields were quantified for individual steps and the overall process chain.

Main Results:

• The two-step process yielded at least 0.95 kg CO and 0.06 kg H2 per kg of polypropylene.
• The energy content of the produced syngas (CO and H2) was approximately 40% of the raw material's energy.
• Characterization confirmed the composition of products from both pyrolysis and gasification.

Conclusions:

• A two-step pyrolysis-gasification process is viable for converting polypropylene waste into syngas.
• The process facilitates the use of challenging circular feedstocks in high-quality syngas production.
• Yields are expected to improve significantly at larger industrial scales due to reduced proportional losses.