Facile preparation of high-performance Fe-doped Ce–Mn/TiO₂ catalysts for the low-temperature selective catalytic reduction of NO_x with NH₃

Abstract

A Ce-Mn-Fe/TiO 2 catalyst has been successfully prepared using a single impregnation method, and excellent low-temperature NH 3 -SCR activity was demonstrated in comparison with other typical SCR catalysts including Mn-Ce/TiO 2 and metal-doped Mn-Ce/TiO 2 . The crystal structure, morphology, textural properties, valence state of the metals, acidity and redox properties of the novel catalyst were investigated comprehensively by X-ray diffraction (XRD), N 2 adsorption and desorption analysis, X-ray photoelectron spectroscopy (XPS), NH 3 -temperature-programmed desorption (NH 3 -TPD), and H 2temperature-programmed reduction (H 2 -TPR). The Fe-doped Ce-Mn/TiO 2 catalyst boosted the lowtemperature NH 3 -SCR activity effectively under a broad temperature range (100-280 C) with a superior NO conversion rate at low temperatures (100 C, 96%; 120-160 C, $100%). Fe doping caused this improvement by enlarging the catalyst pore volume, improving the redox properties, and increasing the amount of acidic sites. These properties enhanced the ability of the catalyst to adsorb NH 3 and improved the low-temperature SCR performance, especially at temperatures lower than 150 C. Moreover, redox cycles of Ce, Mn, and Ti (Mn 4+ + Ce 3+ 4 Mn 3+ + Ce 4+ , Mn 4+ + Ti 3+ 4 Mn 3+ + Ti 4+ ) also played an important role in enhancing the low-temperature SCR efficiency by accelerating the electron transfer.The excellent NH 3 -SCR result is promising for developing environmentally-friendly and more effective industrial catalysts in the future.

Preparation of Ce–Mn/Fe2O3 Catalysts for Steam Catalytic Cracking of Coal Tar

“…This is due to the increase of oxygen mobility on the surface of the catalyst caused by the transformation of Ce 4+ / Ce 3+ . It was also reported that Ce performs excellently in enhancing the oxygen storage capacity of the catalyst and improves the redox activity . According to the H 2 ‐TPR profiles of Fe 2 O 3 based catalysts in Figure , the introduction of CeO x promotes the starting reduction temperature shifting to low temperature.…”

Ethanol Steam Reforming Followed by Water‐Gas Shift Reaction over Ce‐Ni/MCM‐41 and Fe‐Based Catalysts

“…No bands corresponding to La and K were observed in the XRD patterns. This result showed that the promoters (K, La, and Ti) are in the form of small particles and greatly dispersed on the catalyst surface, decreasing the crystallization degree .…”

Preparation and Performance of Cerium-Based Catalysts for Selective Catalytic Reduction of Nitrogen Oxides: A Critical Review

“…More specifically, it could be demonstrated that Ce modified Mn-Ce/TiO2-PILC catalyst enhanced the dispersion of Mn on the surface. Compared with CeO2-MnOx catalyst, the resistance to H2O and SO2 of the Ce-Mn/TiO2 catalyst has been enhanced to some extent [77]. CeO2 can significantly inhibit the deposition of (NH4)2SO4 and NH4HSO4 on the catalyst surface, which is the fundamental reason for the improvement of SO2/H2O resistance [78].…”