Significance of pyrolysis in the circular economy: An integrative review of technologies, potential chemicals, and separation techniques

Promoting value creation is critical for utilizing and valorizing biomass and wastes under the frame of the circular economy. Prioritizing, enabling, and maximizing the production of value-added chemicals is a cornerstone to realizing this goal and giving greater socioeconomic and environmental benefits. Pyrolysis, a key waste-to-X technology, enables converting a wide range of biomass waste into a potentially diverse portfolio of valuable chemicals with the benefits of reducing waste, scaling up potential, and providing flexibility to couple with existing facilities. This integrative review broadly explores the significance of pyrolysis within a circular economy by examining its value chain potential, from diverse feedstocks to hundreds of technological choices and separation techniques, ultimately identifying nearly a thousand organic chemicals in pyrolysis oil. Key findings highlight catalytic pyrolysis with environmentally benign catalysts, and solar pyrolysis reduce energy use by up to 30 %, and hydropyrolysis enhances oil quality. A systematic review of 110 studies identifies oxygenated compounds like acids, esters, and phenols as dominant. While conventional separations rely on distillation, filtration, and extraction, advanced techniques such as reactive distillation, nanofiltration, and supercritical fluid extraction show promise for isolating key compounds like phenols, acetic acid, and furfural, though scalability remains a challenge. A broad and integrative approach enables this study to serve as a benchmark for future research, maximizing value-creation and resource efficiency.