Study on desulfurization performance of Cu modified red mud-fly ash sorbent

Abstract

In this paper, fly ash, red mud and Cu(NO3)2·3H2O were used to prepare Cu modified red mud-fly ash sorbent (CuRMFA) by hydration impregnation method, and the sorbent was used to remove SO2 from coal-fired flue gas. The effects of Cu loading and removal conditions (temperature, O2 concentration and NO concentration) on the desulfurization ability of sorbent were studied. The desulfurization performance and mechanism of CuRMFA were analyzed by experimental results and characterizations. The experimental results show that the sorbent CuRMFA can meet the ultra-low emission standard of SO2, and the optimal load of Cu is 20 mg/g. The optimal removal conditions were 500 ℃, 5% O2, 50 mg/m3 NO and 500 mg/m3 SO2, and when the desulfurization efficiency was greater than 93%, the breakthrough time and sulfur capacity were 65.5 min and 230.88 mg/g, respectively. The CuRMFA mainly removes SO2 by chemical reaction, and the desulfurized product exists in the form of SO42-. The conversion of Cu+ to Cu2+ can enhance the electron transfer, enhance the adsorption oxygen conversion and catalytic oxidation performance, which plays an important role in improving the desulfurization performance of the CuRMFA. That Cu modified RMFA is beneficial to form active component 2MgO·SiO2 and decompose of (CaO)12·(Al2O3)7, and can promote the uniform dispersion of active component, which is conducive to reducing the activation energy of desulfurization reaction and speeding up the reaction process.