Microwave-carbon fiber cloth co-ignited catalytic degradation of waste plastic into high-yield hydrogen and carbon nanotubes

Abstract

Environmental pollution and waste of resources caused by the massive accumulation and landfill of plastic waste has been prompting the research considering its reclamation. In this work, a microwave-carbon fiber cloth (CFC) co-ignited cracking strategy is proposed for highly-efficient conversion of polyethylene to hydrogen and high-quality carbon nanotubes conducted in a simple multimode microwave reactor. When FeAlOx@C is used as the catalyst, a hydrogen yield of 64.5 mmol g−1plastic is achieved while biochar powder as the ignitor only give yield to 30.6 mmol H2 g−1plastic, demonstrating the superiority of the CFC strategy where the carbon ignitor has little contact with the reactants. Further, FeAlOx@C treated by air plasma with rich oxygen vacancies is used as the catalyst. The yield is enhanced significantly, especially at low microwave power, resulting in a hydrogen yield of 67.3 mmol g−1plastic at a microwave power of 900 W, which was the highest as far as we know in the literature under direct catalytic cracking processes. Notably, the integrity of the CFC piece is maintained well, and is highly recyclable. Numerical simulation suggests that the position of CFC plays a key role in initiating the enhanced catalytic cracking process enabled by direct microwave heating.