Analysis of N2O reduction by components of red mud in bubbling fluidized bed

Abstract

Circulating fluidized bed (CFB) technology is developing rapidly, but there is no effective treatment measure for N2O emission. Based on the catalytic theory of metal oxides for N2O, the catalytic performance and apparent activation energy of red mud and its main components for N2O decomposition in gas mixture were measured in a bubbling fluidized bed. The decomposition rate and catalytic rate of different materials were compared. The properties of the materials were similar to those of red mud. The main oxides of red mud were proportioned, and the N2O decomposition experiment was carried out by changing their proportions. The decomposition effect of N2O by various materials in coal-fired process was tested. It is found that all kinds of additives can accelerate the decomposition of N2O with different degrees, but the effect on NO is not significant. When the initial amount of N2O is the same, the catalytic activity of red mud for N2O decomposition is higher than that of single oxide and mixed oxide with different proportions in red mud. The order of catalytic activity for N2O decomposition is: Red mud > CaO > Al2O3 > Fe2O3 > SiO2 > MgO ≈ TiO2. For ammonia injection process, all additives can promote the decomposition of N2O and NO. Compared with other materials, red mud has stronger N2O decomposition ability, lower recovery rate and better economic performance. Iron-containing components can accelerate N2O decomposition, but increase the emission of NO. As a bed material and additive, Al2O3 can achieve better balance between N2O and NO.