Effect of metal oxide and waste-derived activated carbon catalyst on pyrolysis of disposable mask for hydrogen and carbon nanomaterial production

Abstract

Massive disposable masks have been generated in the environment, causing various types of pollution and social concern. To deal with this issue, recent studies have been conducted to recover resources via pyrolysis from waste masks. However, there are few works of enhancing hydrogen productivity by adjusting various catalysts from waste masks. Here, we addressed this issue by utilizing a two-step catalytic pyrolysis system. Non-noble metal catalysts including metal oxides (LaNiO$_3$, Ni/Al$_2$O$_3$, Ni/Zeolite 4A) and waste-derived modified activated carbon catalysts (nickel-loaded activated carbon, sulfonated activated carbon) were adjusted to the catalytic reforming zone. Improved results of maximum hydrogen concentration were investigated from cases of Zeolite 4A and sulfonated activated carbon with modification were inserted into the plastic pyrolysis zone combined with the LaNiO$_3$ at the catalytic reforming stage. Impregnated catalysts that meet a nickel content ratio (Ni(25)/Al$_2$O$_3$, Ni(25)/Zeolite 4A) as LaNiO$_3$ showed a comparable result of hydrogen concentration and structural purity of carbon nanomaterial, implying that the nickel content ratio on the catalyst can be a critical factor of hydrogen production during catalytic pyrolysis. Through this study, it could be expected that these results can contribute to the sustainable production of clean fuel gas products through catalytic pyrolysis to deal with disposable mask wastes.