Hierarchically Engineered Mn3o4-Ceo2/Diatomite-Sba15 Nanocomposite with Dual-Active Sites for Flue Gas Desulfurization

Abstract

The flue gas desulfurization characteristics of Mn-Ce metal oxides supported by the diatomite and SBA-15 are systematically investigated. The framework structure, high mechanical strength and large density of diatomite significantly contribute to the high desulfurization efficiency (96%) of sorbent (M2C2D6). Compared with M2C2D6, the dispersion degree of the active components on SBA-15 is more uniform. The breakthrough sulfur capacity (TSC) of the SBA-15-supported sorbent (M2C2D6) increases sharply from 162 mg-SO2/g-sorbent to 469 mg-SO2/g-sorbent. On the other hand, due to the relatively low density and weak wettability with metal oxides of SBA-15, local exposure occurs on the surface of M2C2S6 sorbent, weakening the contact between SO2 molecules and the active components. Consequently, the desulfurization efficiency of M2C2S6 decreased to 65%. The desulfurization mechanisms of M2C2D6 and M2C2S6 are explored through the analysis of chemical reactions, external mass transfer and internal diffusion. By combining the advantages of diatomite and SBA, a novel Mn-Ce/diatomite-SBA carrier-blended sorbent is developed. As the weight ratio of diatomite to SBA-15 reaches 3:2, the SO2 removal efficiency of 96% and TSC of 193 mg-SO2/g-sorbent are obtained. During five desulfurization-regeneration cycles, the BSC of M2C2D6S4 is consistently higher than that of the single-carrier M2C2D6, demonstrating a significantly high durability.

Keywords: Flue gas desulfurization, Mn-Ce/diatomite-SBA carrier-blended sorbent, Breakthrough sulfur capacity, Cycle performance, Adsorption mechanism