Catalytic pyrolysis of disposable masks: Fine-tuning nickel content ratios in catalysts for enhanced hydrogen-rich gas and carbon nanomaterial quality

Abstract

The widespread use and disposal of disposable masks have raised significant environmental and social concerns. In response to this issue, recent studies have explored resource recovery through the pyrolysis of discarded masks. However, limited research has been conducted on tuning the content ratios of active metal and applying various catalyst supports for targeting hydrogen (H₂) and carbon nanomaterials. To address this gap, we implemented a two-zone catalytic pyrolysis system. The nickel content ratio in non-noble catalysts (Ni/Al₂O₃, Ni/Zeolite 4 A, and LaNiO₃) was fine-tuned and applied in the catalytic reforming zone to optimize hydrogen production and graphite-like carbon nanomaterial formation. Impregnated catalysts (Ni(25)/Al₂O₃, Ni(25)/Zeolite 4 A) and LaNiO₃ demonstrated comparable results in terms of hydrogen concentration up to 64.6 vol% and the structural purity of carbon nanomaterial by Raman Spectroscopy, suggesting that the nickel content ratio on the catalyst plays a critical role in hydrogen production during catalytic pyrolysis. These findings are anticipated to contribute to the sustainable production of clean fuel gas products through catalytic pyrolysis, offering a viable solution to the disposal of waste masks.