Influence of the Chemical Composition of MgAlFeCu Mixed Oxides as Catalysts for SO₂ Removal

Abstract

A series of MgAlFeCu mixed oxides with different chemical compositions derived from hydrotalcite-like compounds were prepared by the NaAlO₂-coprecipitation method and characterized by XRF, XRD, and N₂ adsorption analysis. These sulfur-transfer catalysts were evaluated as SO_x removal catalysts under the conditions similar to those of FCC units. The results showed that the total SO₂ adsorption amounts increased with increasing magnesium content. And the redox properties of Fe₂O₃ enhanced significantly the adsorption-reduction capacities of the catalysts, while CuO can be used as an effective oxidation promoter. Furthermore, the catalyst LDOs-6 (Mg/Al = 6, Fe₂O₃% = 8% and CuO% = 1%) presented the excellent SO₂ removal capacity, its total amounts of adsorbed SO₂ reached 1.74 g /g in 7 min, which also remained constant after eight cycles. These results indicated that the performances of the catalysts were closely related to the chemical composition.

Keywords:

• SO_x removal
• sulfur-transfer catalysts
• hydrotalcite-like compounds
• the NaAlO₂-coprecipitation method
• chemical composition

Additional information

Funding

We gratefully appreciate the financial support from the Natural Science Foundation of China (No. 51204120), the Natural Science Foundation of Shanxi (No. 2014021014-1), and the China Postdoctoral Science Foundation (No. 2012M510782).