GC×GC-Based Characterization and Catalytic Dechlorination of PVC Pyrolysis Oil

Polyvinyl chloride (PVC) releases chlorine-containing compounds when it is turned into oil, which can cause corrosion and other problems if the oil is used as fuel. To deal with this, researchers looked at ways to remove chlorine from PVC-derived oil using two types of catalysts: a commercial palladium-on-carbon (Pd/C) and a lab-made palladium-on-zirconium dioxide (Pd/ZrO₂). The researchers analyzed the oil’s makeup and chlorine content using comprehensive two-dimensional gas chromatography (GC×GC) coupled with flame ionization detection and atomic emission detection. A paper based on this research was published in the journal Energy Fuels.¹

Why is Chlorine in PVC-Derived Oil a Problem, and How Effective Are Current Methods for Removing It?

PVC is one of the most widely used plastics in the world, and its production is expected to keep growing. When PVC waste is turned into oil, it becomes a major source of chlorine-containing compounds, which can also come from salts and other contaminants. These chlorine compounds can cause serious problems, such as equipment corrosion, damage to catalysts, and the release of harmful pollutants. Because of this, strict limits are set on how much chlorine can be present in these oils—often very low, especially in sensitive industrial processes.^2-5

Ways to remove chlorine depend on whether they are done before, during, or after the plastic is heated to make oil. Methods used before or during this process can remove a lot of the chlorine, but not all of it. For example, washing the plastic with hot water or chemicals before heating can help, but the resulting oil can still contain fairly high levels of chlorine. Techniques used during the heating process, such as adding catalysts or other materials, can reduce chlorine further, but even with these steps, some chlorine usually remains in the final oil.^6,7

How Effective are Pd-Based Catalysts at Removing Chlorine from PVC-Derived Pyrolysis Oil?

For this research, PVC plastic was heated in two steps to turn it into oil, which mostly removed the chlorine and left only a small amount behind. The oil was then treated with different catalysts to remove even more chlorine. The Pd/C catalyst showed better performance, because the palladium was more evenly dispersed on its surface compared to Pd/ZrO₂, although it didn’t last as long, and had lower reusability. Overall, the process was able to remove about 82–89% of the remaining chlorine from the oil.¹

“These findings,” write the authors of the paper,¹ “highlight the potential of Pd-based catalysts to reduce chlorine content in PVC pyrolysis oil, thereby enabling its use in cleaner fuel production.”

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References

1. 1Mahmoudi, E.; Hulaj, G.; Auersvald, M. et al. PVC Waste to Fuel: Pyrolysis Oil Upgrading through Catalytic Hydrodechlorination. Energy Fuels 2026, 40 (17), 9546-9559. DOI: 10.1021/acs.energyfuels.6c00289
2. Razzaq, A. U.; Esfahani, M. R. Upcycled PVC Support Layer from Waste PVC Pipe for Thin Film Composite Nanofiltration Membranes. Sep. Purif. Technol. 2024, 340, 126747, DOI: 10.1016/j.seppur.2024.126747
3. Rajenthiran, N.; Zuo, J.; Oteng, D. et al The Role of Polyvinyl Chloride in Achieving Circularity in the Built Environment: A Comprehensive Review. Environ. Impact Assess. Rev. 2026, 116, 108103. DOI: 10.1016/j.eiar.2025.108103
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5. Dong, N.; Hui, H.; Li, S. et al. Study on Preparation of Aromatic-Rich Oil by Thermal Dechlorination and Fast Pyrolysis of PVC. J. Anal. Appl. Pyrolysis 2023, 169, 105817, DOI: 10.1016/j.jaap.2022.105817
6. Genuino, H. C.; Ruiz, M. P.; Heeres, H. J. et al. Pyrolysis of Mixed Plastic Waste (DKR-350): Effect of Washing Pre-Treatment and Fate of Chlorine. Fuel Process. Technol. 2022, 233, 107304, DOI: 10.1016/j.fuproc.2022.107304
7. Romero, A.; Moreno, I.; Escudero, L. Dechlorination of a Real Plastic Waste Pyrolysis Oil by Adsorption with Zeolites. J. Environ. Chem. Eng. 2024, 12 (3), 112638, DOI: 10.1016/j.jece.2024.112638