Red Mud As the Catalyst for Energy and Environmental Catalysis: A Review

Red mud is a solid waste in the production process of Al2O3 using the Bayer process, and most of it is discarded in the storage yard, which not only causes the waste of resources but also causes significant environmental pollution because of its high alkalinity. It should be pointed out that red mud contains a large number of valuable metal elements (e.g., Fe2O3, Al2O3, TiO2, SiO2, etc.), and has the advantages of low cost, high specific surface area, strong sintering/poisoning resistance, and strong regeneration ability. It is a potential catalyst for many reactions, and its development as a catalyst in various fields has a significant impact on environmental protection and the recycling of value-added waste. As a result, red mud as a catalyst has attracted increasing attention. However, currently, there are limited reviews on the utilization of red mud in diverse catalytic applications, and there is a dearth of comprehensive analysis on the significant impact of different characteristics of red mud in various catalytic fields. Herein, this manuscript reviews the research progress on the use of red mud as a catalyst in different environmental and energy catalysis, which mainly focuses on the characteristics of red mud and the key roles of diverse natures of red mud. Especially, the effect of each component of red mud in different catalytic reactions, as well as the impacts of high basicity and high specific surface area on these reactions, are highly discussed.