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

Department of Environmental Science and Engineering, North China Electric Power University, Baoding 071003, China

^*2 Corresponding author : haozhang0808@163.com
¹ wsqhg@163.com
³ 401279252@qq.com
⁴ 1798822911@qq.com

Abstract

In order to mitigate the emissions of NOx, SO₂, 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-TiO₂ was synthesized using a microwave-sol-gel method. CaO and Cu-TiO₂ 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 SO₂ 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 TiO₂ crystals: an increase in anatase crystal content, enhancement in specific surface area, reduction in particle size, augmentation of O₂ adsorption sites, improved crystallinity, all contributing to heightened catalytic activity. The activation effect on TiO₂ by CaO was confirmed through infrared spectrum analysis; both components exhibited synergistic effects during coal combustion reactions. Specifically, CaO facilitated denitrification processes involving TiO₂ while TiO₂ enhanced desulfurization activities associated with CaO. TG analysis further validated the combustion-supporting role played by Cu-TiO₂. Additionally, XRF analyses indicated that incorporating Cu-TiO₂ 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.