Chemical Recycling of PVC: From Laboratory Promise to Industrial Reality
PVC's chlorine-rich chemistry and diverse additives make large-scale recycling challenging, with only a tiny fraction currently recycled globally. Mechanical recycling is limited to pure streams, yielding low-quality products. Chemical recycling offers a promising alternative, breaking PVC into molecular components. Three main approaches are explored: gasification, producing syngas; pyrolysis, which struggles with corrosive chlorine; and dechlorination, a critical pre-treatment step to remove chlorine, enabling more effective downstream processing and mitigating issues for subsequent chemical conversion methods.
Polyvinyl chloride (PVC) presents unique challenges for recycling due to its complex, chlorine-rich chemistry and diverse formulations, including various additives like plasticizers and stabilizers. While global demand for PVC is projected to rise significantly, current recycling rates are extremely low, with only an estimated 1.2% expected to be recycled by 2032, leading to substantial landfill waste. Mechanical recycling, effective for pure plastic streams, is largely unsuitable for PVC because its additives and contaminants severely downgrade the quality of the recyclate, making it unusable for many original applications.To address these limitations, chemical recycling is emerging as a critical pathway. This method breaks PVC down to its molecular components, allowing for either reconstruction or conversion into valuable chemicals. Three primary chemical recycling approaches are being investigated. Gasification involves partially oxidizing PVC waste at high temperatures (800–1,100°C) to yield syngas, a valuable fuel or chemical feedstock, with ongoing research focusing on improving efficiency and chlorine capture. Pyrolysis, the thermal decomposition of PVC without oxygen, generates oils, gases, and char; however, PVC's high chlorine content leads to highly corrosive hydrogen chloride and contaminated products, preventing commercial-scale application. The third approach, dechlorination, is increasingly seen as a crucial enabling step rather than a standalone recycling method. It aims to selectively remove chlorine from the polymer backbone *before* high-temperature processing. This pre-treatment mitigates corrosion, reduces toxic chlorinated byproducts, and enhances the overall stability and effectiveness of subsequent chemical conversion processes like pyrolysis or further cracking, moving PVC recycling from laboratory promise to industrial reality.
