Iron oxide-based catalysts for low-temperature selective catalytic reduction of NOx with NH3

Abstract Selective catalytic reduction (SCR) is now an established NOx removal technology for industrial flue gas as well as for diesel engine exhaust gas. However, it is still a big challenge to develop a novel low-temperature catalyst for NH3-SCR of NOx, especially at a temperature below 200°C. In the past few years, many studies have demonstrated the potential of iron (Fe)-based catalysts as low-temperature catalysts for NH3-SCR of NOx. Herein, we summarize the recent progress and performance of Fe-based catalysts for low-temperature NH3-SCR of NOx. Catalysts are divided into three categories: single FexOy, Fe-based multimetal oxide, and Fe-based multimetal oxide with support catalysts. The catalytic activity and selectivity of Fe-based catalysts are systematically analyzed and summarized in light of some key factors such as activation energy, specific surface area, morphology, crystallinity, preparation method and precursor, acid sites, calcination temperature, other metal dopant/substitute, and redox property of catalysts. In addition, H2O/SO2 tolerance and the NH3-SCR reaction mechanism over Fe-based catalysts, including Eley-Rideal and Langmuir-Hinshelwood mechanism, are emphasized. Lastly, the perspectives and future research directions of low-temperature NH3-SCR of NOx are also proposed.

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Modification of Nano Spherical-Like MnOx/TiO2 Catalysts with F-Doped

Materials Science Forum ◽

10.4028/www.scientific.net/msf.898.1896 ◽

2017 ◽

Vol 898 ◽

pp. 1896-1904

Author(s):

Jun Lin Xie ◽

Feng Xiang Li ◽

Hai Feng Cui ◽

Feng He ◽

Kai Qi

Keyword(s):

Catalytic Activity ◽

Low Temperature ◽

Selective Catalytic Reduction ◽

Spherical Particle ◽

Surface Area ◽

Catalytic Reduction ◽

Sol Gel ◽

Acid Sites ◽

Scr Of No ◽

Structures And Properties

A series of spherical-like MnOx/TiO2 catalysts with F-doped were prepared by using sol-gel method and investigated for low-temperature selective catalytic reduction (SCR) of NOx with NH3 at the temperature ranging from 100 °C to 200 °C. The 0.07Ce-MnOx/TiO2 catalyst shows the highest activity and yields 95% NO conversion at 200 °C. With the help of XRD, TGA, H2-TPR, NH3-TPD, BET and TEM, the structures and properties of the catalysts were characterized. The results show that it is a fine modifier for TiO2 support with appropriate amounts of F doping, and F ions can enter into TiO2 lattice, reducing the formation of rutile TiO2 and the crystallization of MnOx. However, MnTiO3 was generated in the catalysts with excess F doping. This would cause larger diameter of spherical particle and smaller surface area. But the amounts of the surface acid sites increased, and the reduction ability of catalysts was enhanced, which is beneficial for catalytic activity of the catalysts.

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Study on Carbon Catalyst for Selective Catalytic Reduction of NOx at Low Temperature

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.448-453.868 ◽

2013 ◽

Vol 448-453 ◽

pp. 868-873

Author(s):

Xiang Gou ◽

Kai Zhang ◽

Lian Sheng Liu ◽

Wen Yong Liu ◽

Zi Fang Wang ◽

...

Keyword(s):

Low Temperature ◽

Selective Catalytic Reduction ◽

Catalytic Reduction ◽

Catalyst Activity ◽

Research Work ◽

Research Progress ◽

Future Research ◽

Carbon Catalyst ◽

Removal Technology ◽

Low Temperature Scr

The method of selective catalytic reduction (SCR) is now one of the mature applications of NOx removal technology, which has the higher denitration rate, less secondary pollution and lower cost. However, the active temperature of traditional SCR catalyst is usually in the temperature range of 300-400°C. This kind of installation leads to the reduction of catalyst activity, and the shortage of working life. The development of efficient and stable performance of catalyst at low temperature has become a key point in the research of SCR.This paper reviews the research progress of carbon catalyst of low temperature SCR. In addition, the future research work is discussed.

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Different Precipitant Preparation of Nickel-Doped Mn/TiO2 Catalysts for Low-Temperature SCR of NO with NH3

Materials Science Forum ◽

10.4028/www.scientific.net/msf.913.976 ◽

2018 ◽

Vol 913 ◽

pp. 976-984

Author(s):

Xiao Yu Ma ◽

Guo Lan Tian ◽

Su Ping Cui ◽

Ya Li Wang

Keyword(s):

Hydrogen Peroxide ◽

Low Temperature ◽

Catalytic Reduction ◽

Acid Sites ◽

Weak Acid ◽

Precipitation Method ◽

Scr Of No ◽

And Performance ◽

Co Precipitation ◽

Low Temperature Scr

The Mn-Ni/TiO2 catalyst was prepared by co-precipitation method and investigated for the low-temperature selective catalytic reduction (SCR) of NO with NH3 in this work, and Mn-Ni/TiO2 catalysts were prepared by different precipitants respectively such as sodium hydroxide, carbamide, ammonia or hydrogen peroxide. The microstructure and performance of catalysts were investigated. The activitiesof catalysts prepared by different precipitants were studied in the temperature range 90°C-350°C. The results show that Mn-Ni/TiO2catalyst prepared by CO(NH2)2-NH3·H2O-H2O2 compound precipitant has an extraordinary performance even at the low temperature of 120°C. H2-TPR results show the peak positions shift to lower temperatures, standing for the reduction potential of MnOx species is increased compared to those of Mn/TiO2 catalysts. The interaction of Ni and Mn atoms is beneficial to an enhancement of the oxygen mobility due to CO(NH2)2-NH3·H2O-H2O2 as precipitant. It is worth noting that the low temperature peak area increased by adding hydrogen peroxide as precipitant. NH3-TPD results illustrat that for the Mn/TiO2 and Mn-Ni/TiO2 catalysts which are attributed to NH3 desorbed by weak acid sites and Brønsted acid sites.

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Theoretical Design of Transition Metal-Doped TiO2 for the Selective Catalytic Reduction of NO with NH3 by DFT Calculations

Catalysis Science & Technology ◽

10.1039/d1cy02214h ◽

2022 ◽

Author(s):

Huiling Zheng ◽

Renjie Li ◽

Chengming Zhong ◽

Zhi Li ◽

Yikun Kang ◽

...

Keyword(s):

Low Temperature ◽

Transition Metal ◽

Selective Catalytic Reduction ◽

Transition Metal Oxides ◽

Catalytic Reduction ◽

Trade Off ◽

Reduction Of No ◽

Theoretical Design ◽

Scr Of No ◽

Metal Doped

Many transition metal oxides supported on TiO2 have been studied for selective catalytic reduction (SCR) of NO with NH3. However, the trade-off exists between the low-temperature activity and N2 selectivity....

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Nanosized V-Ce Oxides Supported on TiO2 as a Superior Catalyst for the Selective Catalytic Reduction of NO

Catalysts ◽

10.3390/catal10020202 ◽

2020 ◽

Vol 10 (2) ◽

pp. 202

Author(s):

Long Lu ◽

Xueman Wang ◽

Chunhua Hu ◽

Ying Liu ◽

Xiongbo Chen ◽

...

Keyword(s):

Low Temperature ◽

Selective Catalytic Reduction ◽

Photoelectron Spectroscopy ◽

Catalytic Reduction ◽

X Ray Diffraction ◽

X Ray ◽

Transmission Electron ◽

Redox Capacity ◽

Scr Of No ◽

Temperature Programmed

Nanosized V-Ce oxides supported on TiO2 (VCT) were prepared and utilized in the low-temperature selective catalytic reduction (SCR) of NO with NH3. Compared with the other V-Ce oxides-based catalysts supported on Al2O3, ZrO2, and ZSM-5, VCT showed the best SCR activity in a low-temperature range. The NOx conversion of 90% could be achieved at 220 °C. Characterizations including X-ray diffraction (XRD), scanning election micrograph (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), temperature-programmed desorption with NH3 (NH3-TPD), and temperature-programmed reduction with H2 (H2-TPR) showed that V1.05Ce1/TiO2 exhibited a good dispersion of V2O5, enrichment of surface Ce3+ and chemical-absorbed oxygen, and excellent redox capacity and acidity, which resulted in the best SCR performance at low temperature.

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Effect of the calcination temperature of cerium–zirconium mixed oxides on the structure and catalytic performance of WO3/CeZrO2 monolithic catalyst for selective catalytic reduction of NOx with NH3

RSC Advances ◽

10.1039/c7ra03054a ◽

2017 ◽

Vol 7 (39) ◽

pp. 24177-24187 ◽

Cited By ~ 15

Author(s):

Haidi Xu ◽

Mengmeng Sun ◽

Shuang Liu ◽

Yuanshan Li ◽

Jianli Wang ◽

...

Keyword(s):

Low Temperature ◽

Selective Catalytic Reduction ◽

Lewis Acid ◽

Mixed Oxides ◽

Catalytic Reduction ◽

Catalytic Performance ◽

Acid Sites ◽

Lewis Acid Sites ◽

Reduction Of Nox ◽

Calcined Temperature

The calcined temperature of the carrier obviously affected SCR activity of catalysts, WO3/Ce0.68Zr0.32O2-500 showed the best low-temperature NH3-SCR activity due to its more Lewis acid sites and stronger redox property.

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