Modification to Enhance Surface Acidity and Reactive Species of Coal Fly Ash: A Study of Efficient NOX Removal

This paper presents a method for efficiently removing nitrogen oxides produced during cement production by utilizing coal fly ash, a common substitute in cement raw materials. The surface acidity and reactive species content of coal fly ash were improved by acid–base modification to participate in the cement production process for efficient NOX removal. In this work, the activity of modified coal fly ash in the denitration reaction and the adsorption and reaction mechanism of NH3+NO+O2 on its surface were explored. The research results show that the NO conversion of modified coal fly ash reaches more than 94% in the range of 800–1000 °C. The modification process of base activation and acid precipitation promoted the formation of pores and the exposure of active components on the surface of the coal fly ash, increasing the number of acidic sites and oxygen vacancies. The DRIFTS results indicated that NH3 and NO were coadsorbed on the modified coal fly ash, formed active intermediates, and eventually decomposed into N2, achieving the high efficiency of NOX removal. This study provides an efficient method to remove NOX from cement production using modified coal fly ash, which gives a new idea for low-carbon cement production.