Enhanced decomposition of CF₄ by a composite material upcycled from acid-modified red mud and γ-Al₂O₃

CF₄, is a highly potent greenhouse gas emitted by the electrolytic aluminum industry, with a global warming potential 7390 times that of CO₂. Its urgently necessary to effectively control and decompose it. Alumina industry is the upstream of electrolytic aluminum industry, from which the red mud (RM) generated should be recycled. In this study, the decomposition performance of CF₄ was improved by loading γ-Al₂O₃ on hydrochloric acid-treated RM. Under optimal conditions (reaction temperature of 650 °C, WHSV of 1500 h^-1, and material dosage of 1 g), the decomposition efficiency of Al₁HRM₂ for CF₄ reached 85 %. Compared with the unmodified acid-treated RM (HRM), the conversion rate and stability were significantly improved. The results of NH₃-TPD, Py-IR and XPS indicated that acid treatment and addition of γ-Al₂O₃ significantly increased the Lewis acid site and medium-strong acid site of Al₁HRM₂. During the reaction, CF₄ adsorbs and dissociates at the strongest Lewis acid site (Al_Ⅲ), forming an intermediate (CF₂O) and CO₂ to achieve the decomposition of CF₄. In comparison with existing decomposition techniques, the method proposed here avoids the generation of corrosive HF, while also promoting the development of a greener aluminum industry and the formation of high-value fluorides.