Coupling pyrolysis and catalytic reforming of waste plastics for syngas production over confined Ni within silicalite-1 catalysts

Thermochemically upcycling waste plastics to value-added products is emerging to alleviate the waste crisis. This study aims to develop highly active and stable Ni-based catalysts for coupling pyrolysis and catalytic reforming of waste plastics to produce syngas. A series of confined NiO@S-1 catalysts with various Ni loadings (5%, 10%, 15%, and 20%) were constructed by employing dissolution-recrystallization strategy. They were in situ reduced and 15%NiO@S-1 sample showed the highest catalytic activity in terms of yield of syngas with high CO selectivity and was superior to 15%NiO/S-1 and 15%NiO/SiO 2 samples prepared by impregnation method. The TEM images of 15%NiO@S-1 catalyst after reaction showed that metallic Ni nanoparticles with average size of 10.1 nm were kept dispersive due to the confinement effect. In contrast, the apparent agglomeration of Ni nanoparticles with average size of 54.9 nm were found on the surface of 15%NiO/S-1 after reaction. This provides an effective strategy for design robust Ni-based confined catalysts for thermochemically upcycling waste plastics.