Promotion of Cu/Ce supported red mud for NO removal from low and medium temperature flue gas

Red mud is a solid waste in aluminum industry and has been proven to be an efficient alternative to NO_x selective catalytic reduction (SCR) catalysts. Acid washing treatment to red mud can improve its alkalinity and surface properties, and increase the conversion rate of NO_x. In this paper, Cu, Ce, and Cu/Ce was supported on acid washed red mud and NO_x catalytic conversion performance on metal modified red mud catalysts was studied. The research results indicate that Cu⁺ and Cu²⁺ in the Cu supported catalyst effectively promote NO conversion rate of red mud in low-temperature (200–300 °C) flue gas, reaching a maximum of 90.7%; Ce³⁺ and Ce⁴⁺ in Ce supported catalysts effectively promote the NO conversion rate of red mud in flue gas at 200–400 °C, reaching a maximum of 94.0%; Cu/Ce supporting exhibits better NO conversion rate than single metal supported catalysts at low-temperatures, the optimal Cu:Ce ratio for supporting is 1:1; and also exhibits better NO conversion rate than Cu supported catalysts at high-temperature (300–400 °C), reaching a maximum of 95.5%. The reason may be that under the synergistic effect of Cu/Ce, ACRM-Cu1Ce1 has stronger low-temperature redox ability, higher weak acidic peaks, higher average oxidation state of Fe ions, and higher Cu⁺ content.