Recent advances in analytical methods for plastic thermochemical conversion: from feedstocks to products

The rising accumulation of plastic waste poses a global challenge, highlighting the need for efficient recycling and valorization. Thermochemical conversion offers a promising route for transforming plastics into value-added products, but its optimization relies on robust analytical methods capable of accurately identifying feedstocks and characterizing reaction products. This review summarizes recent advances in analytical methods across the entire thermochemical conversion chain. For feedstock identification, conventional sorting manual and density-based sorting have evolved toward advanced spectroscopic techniques like Fourier-transform infrared and Raman, enabling rapid and non-destructive polymer detection. For product characterization, chromatographic, thermal, spectroscopic, and microscopic tools are essential for analyzing gaseous, liquid, and solid products and for uncovering reaction pathways. Emerging integration of artificial intelligence and machine learning is also highlighted for enhancing real-time analysis and process decision-making. Therefore, this review offers guidance for selecting and applying analytical tools to improve the environmental and economic feasibility of thermochemical plastic recycling. • Analytic methodologies covering the full plastic thermochemical conversion chain; • Key spectroscopic, chromatographic, thermal, and microscopic techniques summarized; • Advances from conventional sorting to advanced spectroscopic identification highlighted; • Advanced analytics elucidating reaction mechanisms and product evolution emphasized; • Emerging artificial-intelligence-assisted methods and future research directions examined.