Study on the Synergistic Promotion of NOx Reduction in Coal Combustion by CaO and Cu-TiO₂

In order to mitigate the emissions of NOx, SO 2 , and other harmful gases generated from coal combustion, as well as to achieve simultaneous desulfurization and denitrification during the combustion of medium- and high-sulfur coal, Cu-TiO 2 was synthesized using a microwave-sol-gel method. CaO and Cu-TiO 2 were ground together and mixed with experimental coal as additives. The experiments were conducted under an oxygen flow rate of 40 mL/min at a temperature of 850°C. The results show that the removal rates of SO 2 and NOx are as high as 89.10% and 48.48%, respectively, while the amount of catalyst used constituted only 6% of the mass of coal. Characterization and analysis of the reactants were performed; XRD and BET results demonstrated that upon adding Cu in its +2 valence state, there is a notable alteration in the surface structure of TiO 2 crystals: an increase in anatase crystal content, enhancement in specific surface area, reduction in particle size, augmentation of O 2 adsorption sites, improved crystallinity, all contributing to heightened catalytic activity. The activation effect on TiO 2 by CaO was confirmed through infrared spectrum analysis; both components exhibited synergistic effects during coal combustion reactions. Specifically, CaO facilitated denitrification processes involving TiO 2 while TiO 2 enhanced desulfurization activities associated with CaO. TG analysis further validated the combustion-supporting role played by Cu-TiO 2 . Additionally, XRF analyses indicated that incorporating Cu-TiO 2 can enhance slagging behavior within coal ash. The plan can be applied in coal-fired power plants in the future that use complex and variable coal types in order to reduce production costs, save energy and pollution, and conserve resources.