Effects of Ni/Al₂O₃ catalyst treatment condition on thermocatalytic conversion of spent disposable wipes

Municipal solid waste (MSW) management is an essential municipal service. Proper waste treatment is an important part of the waste management. Thermocatalytic waste upcycling has recently gained great interest and attention as a method to extract value from waste, which potentially substitutes traditional waste treatment methods. This study aims at demonstrating the potential for thermocatalytic waste upcycling using spent disposable wipes as an MSW surrogate. Two different Ni/Al₂O₃ catalysts were prepared, treated under two different atmospheres (N₂ and CO₂). The catalyst treated in N₂ (Ni/Al₂O₃-N₂) exhibited a higher surface metallic Ni site than the catalyst treated in CO₂ (Ni/Al₂O₃-CO₂). The use of the Ni/Al₂O₃-N₂ increased the yield of gas pyrolysate and decreased the yield of byproduct (e.g., wax), compared with no catalyst and the Ni/Al₂O₃-CO₂. In particular, the Ni/Al₂O₃-N₂ catalyst affected the generation of gaseous hydrogen (H₂) by increasing the H₂ yield by up to 102% in comparison with the other thermocatalytic systems. The highest H₂ yield obtained with the Ni/Al₂O₃-N₂ was attributed to the most surface metallic Ni sites. However, the Ni/Al₂O₃-N₂ catalyst led to char having a lower higher heating value than the other catalysts due to its lowest carbon content. The results indicated that the reduction treatment environment for Ni/Al₂O₃ catalyst influences thermocatalytic conversion product yields of spent disposable wipes, including enhanced H₂ production.

Supplementary material is available in the online version of this article at 10.1007/s11814-023-1461-8.