Research Progress in Fly Ash-supported Catalysts for Selective Catalytic Reduction of NOx with NH₃

NH₃-SCR is considered to be the most effective way to remove NOx from coal-fired flue gas, and the key is the catalyst. Fly ash is employed as catalyst carrier in the SCR process for its superior properties, such as low cost, easy availability and including silicon-aluminum structure and pore structure. The catalyst, composed of fly ash, exhibits good denitration activity after loading and modification, and it can achieve the purpose of waste resource utilization. In this paper, the research progress of fly ash as catalyst in SCR denitration is summarized, and the main influence factors on their denitrification performance are reviewed in terms of active ingredient, preparation method, precursor, calcination temperature. In addition, the effects of acid modification and alkali modification on the performance of the catalyst are introduced, and the denitration mechanism of fly ash is also analyzed briefly. Furthermore, the denitration catalyst forming problem of fly ash used in SCR is introduced in detail and extrusion molding is widely used for its advantages. Considering some of the problems that impact performance in large-scale applications to the denitrification of power plants to reduce the cost of flue gas denitrification, the shortcomings of the existing research on fly ash and the future research directions are pointed out.