Decoding Chlorine Contaminants in Plastic-Derived Pyrolysis Oils with Chlorine-Selective GC×GC-AED.

Area of Science:

• Analytical Chemistry
• Environmental Science
• Materials Science

Background:

• Chlorine in plastic pyrolysis oils hinders steam cracking valorization due to strict feed requirements (<3 ppm).
• Existing methods lack elemental selectivity and compound-independent quantification for complex pyrolysis matrices.

Purpose of the Study:

• To develop and validate a chlorine-selective, quantitative GC×GC-AED method for analyzing chlorine in postconsumer plastic pyrolysis oils.
• To enable precise identification and quantification of chlorine-containing compounds in diverse plastic waste streams.

Main Methods:

• Systematic optimization of atomic emission detection (AED) parameters for chlorine selectivity and sensitivity.
• Development of a quantitative comprehensive two-dimensional gas chromatography (GC×GC) method using a chlorine-selective AED.
• Validation using 28 model compounds and analysis of seven real pyrolysis oil samples from PVC and mixed plastic waste.

Main Results:

• The GC×GC-AED method demonstrated largely compound-independent response (<5% variability).
• 85-99% of detected chlorine compounds were tentatively identified and quantified in various pyrolysis oils.
• Results from GC×GC-AED showed close agreement (<5% variation) with combustion microcoulometry and X-ray fluorescence (XRF).

Conclusions:

• The developed GC×GC-AED method is a powerful, reliable tool for analyzing chlorine in complex pyrolysis oils.
• This technique is crucial for understanding chlorine transformation pathways in plastic waste valorization.
• The method supports the development of effective dechlorination strategies for improved plastic recycling.