Enhancing light fuel production through catalytic pyrolysis of municipal mixed plastic waste over activated spent FCC catalyst

Abstract

To address the issue of environmental pollution caused by waste plastics and increase their recycling utilization, a cost-effective chemical recycling method was employed in this study. It involved the use of spent fluid catalytic cracking (FCC) catalysts to convert waste plastics into valuable products. Sequential nitric acid treatment and pore expansion by ammonium hexafluorosilicate methods were employed to activate the spent FCC catalyst, with the aim of improving its physicochemical properties and enhancing the production of light fuel. The results demonstrated that activation treatment of the spent FCC catalyst improved the external surface area and meso-macroporous volumes of the activated catalysts. This process facilitated the initial cracking reaction of polyolefin macromolecules and alleviated the diffusion limitations of reactants and products within the pores of the catalyst, resulting in an increase in the yield of light fuels. Compared to the spent FCC catalyst, the activated catalysts exhibited 5.79–19.49% higher selectivities for light olefins and 21.67–29.76% higher yields for light fuels. These findings provide potential opportunities for the valuable utilization of waste plastics.