Influence of Y Doping on Catalytic Activity of CeO2, MnOx, and CeMnOx Catalysts for Selective Catalytic Reduction of NO by NH3

Abstract

Novel yttrium-doped CeO2, MnOx, and CeMnOx composites are investigated as catalysts for low-temperature NH3-SCR. The study involves the preparation of unmodified oxide supports using a citrate method followed by modification with Y (2 wt.%) using two approaches, including the one-pot citrate method and incipient wetness impregnation of undoped oxides. The NH3-SCR reaction is studied in a fixed-bed quartz reactor to test the ability of the prepared catalysts in NO reduction. The gas reaction mixture consists of 800 ppm NO, 800 ppm NH3, 10 vol.% O2, and He as a balance gas at a WHSV of 25,000 mL g−1 h−1. The results indicate that undoped CeMnOx mixed oxide exhibits significantly higher deNOx performance compared with undoped and Y-doped MnOx and CeO2 catalysts. Indeed, yttrium presence in CeMnOx promotes the competitive NH3-SCO reaction, reducing the amount of NH3 available for NO reduction and lowering the catalyst activity. Furthermore, the physical-chemical properties of the prepared catalysts are studied using nitrogen adsorption/desorption, XRD, Raman spectroscopy, temperature-programmed reduction with hydrogen, and temperature-programmed desorption of ammonia. This study presents a promising approach to enhancing the performance of NH3-SCR catalysts at low temperatures that can have significant implications for reducing NO emissions.

Ce–Zr–Mn Oxide Catalysts for Soot Combustion: The Role of Preparation Method

“…Recently, more attention has been given to the CeO 2 -based soot combustion catalyst (Ag/CeO 2 , − Ag–K/CeO 2 –ZrO 2 –Al 2 O 3 , Pt/CeO 2 , Bi-doped CeO 2 , Cu/CeO 2 , etc.). The influence of methods to produce mesoporous CeO 2 , such as sol–gel, hydrothermal, soft and hard templates, etc., was discussed. , The approaches to produce individual and mixed oxides using metal–organic precursors, among which much attention is paid to metal citrate complexes, is often used to synthesize the catalysts and supports due to the simplicity and ability to control the porous structure of the materials. − …”

Unraveling the Structural and Compositional Peculiarities in CTAB-Templated CeO2-ZrO2-MnOx Catalysts for Soot and CO Oxidation

“…Among such materials, ceria brings about high research interest [13] since it demonstrates enhanced abilities to accumulate and release oxygen, and features rather low costs. To further boost CeO 2 performance in terms of improved oxygen mobility and capacity as well as mechanical characteristics, the interactions of ceria with other oxides, i.e., ZrO 2 , MnO x , SnO 2 , are considered in binary and ternary formulations [14][15][16][17][18][19][20]. In a number of cases, the ternary mixed oxide systems exhibited rather high performance, while the reasons for such a behavior remain under debate.…”