Utilizing red mud from industrial waste as catalysts for the hydrogenation of CO2 into value added chemicals

Abstract

Finding environmentally acceptable and long-lasting catalysts that can convert carbon dioxide into compounds with additional value is of great interest. Using Red Mud (RM), a waste product from the aluminum industry, as a CO₂ reduction agent is also a great idea, given the current environmental problems. In this research, we developed, characterized, and evaluated a series of metal-promoted (M = Na, K, Cs, Ba, Mg, and Sr) RM catalysts for CO₂ hydrogenation to produce olefins and CO. In the beginning, we synthesized RM that had been treated with acid and base by employing hydrochloric acid (HCl) and potassium hydroxide (KOH), and then we examined the activity of these catalysts in CO₂ hydrogenation. Surprisingly, when tested at 375 °C and 30 bar pressure (CO₂ : H₂ = 1 : 3), pure RM converted 22% CO₂ compared to acid-and base-treated RM, which converted 16% of CO₂. Under identical reaction conditions, the 3%K-promoted RM (3%K@RM) catalyst achieved over 27% of CO₂ conversion activity compared to the other 3%M@RM catalysts (where M = Na, Cs, Ba, Mg, and Sr) in terms of conversion and selectivity for light olefins (C_2–4=).