Catalytic adsorption and decomposition of per(fluorinated) compounds using zeolites for greenhouse gas mitigation

Abstract

Per(fluorinated) compounds (PFCs/FCs) are a class of synthetic chemicals that are widely used in various industrial applications because of their unique properties. However, in recent years, their abundance in the environment has resulted in serious adverse effects on human health, raising crucial concerns in the environmental field. In this study, zeolites (Beta, Y, and ZSM-5) were used as catalysts for the decomposition and adsorption of PFCs/FCs (CF₄, SF₆, NF₃, C₃F₈, and C₄F₈) by varying the temperature, pH, and contact time. Field emission scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy were employed to characterize the zeolite before and after the decomposition of the PFCs/FCs. A 100% complete decomposition of SF₆ was observed when using ZSM-5, followed by a 75% and 45% decomposition when using Beta and Y zeolites, respectively. A 100% decomposition of NF₃ was achieved by all zeolites (Beta, Y, and ZSM-5). ZSM-5 decomposed CF₄, C₃F₈, and C₄F₈ to produce CO₂ with the following removal rate: CF₄ (80%) > C₃F₈ (60%) > C₄F₈ (25%). The decomposition of SF₆ and CF₄ produces SOF₂, SOF₄, SO₂F₂, and CO₂, whereas that of NF₃ yields SiF₄ and NO. The reaction constants K of catalytic decomposition were calculated to be in the order: Y > Beta > ZSM-5. These results suggest that zeolite catalysts possess great potential as cost-effective and environmentally friendly catalysts for the decomposition of PFC/FC, thus reducing its adverse effects on the environment.