Fabrication of manganese-based Zr-Fe polymeric pillared interlayered montmorillonite for low-temperature selective catalytic reduction of NO x by NH 3 in the metallurgical sintering flue gas

Abstract

A series of Zr-Fe (Zr/Fe = 4:0, 3:1, 2:2, 1:3, 0:4) polymeric pillared interlayered montmorillonite loading 10 wt.% MnO_x (Mn/Zr-Fe-PILM) were investigated for the selective catalytic reduction of NO_x by NH₃ (NH₃-SCR) in metallurgical sintering flue gas. The X-ray diffraction (XRD), N₂ adsorption-desorption isotherm, scanning electron microscope (SEM), and ammonia temperature-programmed desorption (NH₃-TPD) were used to analyze the physicochemical property. The Fe polymerized with Zr exchanged to montmorillonite can improve the Mn/Zr-Fe-PILM low-temperature NO_x conversion and N₂ selectivity. The Mn/Zr-Fe-PILM (1:3) shows the highest NO_x conversion between 140 and 180 °C. The XRD results suggest that the growth of crystalline ZrO₂ phase is intensely restrained for the Fe₂O₃ migration into the ZrO₂ lattice. The ZrO₂ and MnO_x have an excellent dispersion in montmorillonite. The N₂ adsorption result illustrates that the increase of Fe molar content in the Zr-Fe-PILM support increases the catalyst-specific surface area. The NH₃-TPD results elucidate that the Mn/Zr-Fe-PILM (1:3) has the most total acid sites. Therefore, the low-temperature catalytic activity of the Mn/Zr-Fe-PILM (1:3) has been assigned to the large specific surface area, abundant acid sites, and the dispersion of metallic oxides.

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