《Low-Temperature Selective Catalytic Reduction Catalysts（低温SCR催化剂）》系统性的阐述了低温SCR催化剂的国内外研究现状和*新研究进展，为早日实现低温SCR催化剂提供理论依据和技术支撑。《Low-Temperature Selective Catalytic Reduction Catalysts（低温SCR催化剂）》*先介绍了NOx的特性、危害和形成机理，然后介绍了现阶段氮氧化物的控制技术和低温SCR催化反应机理，读者可以基本了解低温SCR催化剂。接下来的两章主要介绍了低温SCR催化剂的制备方法和表征技术手段，读者可以掌握研究低温SCR催化剂的主要技术方法，从而更好的开展课题研究。*后三章重点阐述了Mn基、Ce基以及低温SCR催化剂的抗中毒机理研究现状，给读者朋友带来*前沿的低温SCR催化剂研究情况。《Low-Temperature Selective Catalytic Reduction Catalysts（低温SCR催化剂）》对于想进入低温SCR催化剂研究的学者提供很好的入门参考，更快的掌握低温SCR催化剂的研究方法。对于正在研究低温SCR催化剂的学者提供了研究方向。

Chapter 1
　　The Harm of NOx and Its Emission
　　1.1 NOx
　　1.L1 The Characteristic ofNOx
　　Nitrogen oxide (NOx) refers to a compound composed only of nitrogen and oxygen， including a variety of compounds， such as nitrogen monoxide (N2O)， nitric oxide (NO)， nitrogen dioxide (NO2)， nitrogen trioxide (N2O3)， nitrogen tetxoxide (N2O4) and nitrogen pentoxide (N2O5). In addition， there are nitrosyl azide (N4O) and nitrogen trioxide (NO3). Trinitroamine N(N〇2)3 is also a compound composed only of nitrogen and oxygen elements， but it is not an oxide in the strict sense. Except for nitrous oxide and nitrogen dioxide， other nitrogen oxides are unstable. When exposed to light， humidity， or heat， they become nitrogen dioxide and nitric oxide， and nitric oxide becomes nitrogen dioxide. Therefore， the environment is exposed to several gas mixtures， often called nitrous smoke (gas)， mainly nitric oxide and nitrogen dioxide， and mainly nitrogen dioxide. Nitrogen oxides have different degrees of toxicity.
　　N2O3 and N2O5 are acidic oxides. The corresponding acid of N2O3 is nitrous acid (HNO2)， and N2O3 is the anhydride of nitrous acid; The corresponding acid of N2O5 is nitric acid， and N2O5 is the anhydride of nitric acid. NO， N2O， N2O4 and NO2 are not acid oxides. Nitrogen tetroxide (N2O4) is a dimer of nitrogen dioxide (NO2)， which is often mixed with nitrogen dioxide (NO2) to form an equilibrium mixture. The mixture of nitric oxide (NO) and nitrogen dioxide (NO2)， also known as nitrate gas (nitrate smoke). They are slightly soluble in water， and the aqueous solution is acidic in varying degrees. Nitric oxide (NO) and nitrogen dioxide (NO2) decompose into nitric acid and nitrogen oxide in water. Nitrous oxide (N2O) has strong oxidation only when it is above 300 °C， and the rest have different degrees of oxidation， especially nitrogen pentoxide (N2O5)， which decomposes above — 10 °C to release oxygen and laughing gas. Nitrogen oxides are noncombustible substances， but they can support combustion. For example， nitrogen monoxide (N2O)， nitrogen
　　dioxide (NO2) and nitrogen pentoxide (N2O5) can cause explosion in case of high temperature or combustible substances.
　　Under the condition of high-temperature combustion， NOx mainly exists in the form of NO， and NO accounts for about 95% of the initial NOx emission. However， NO easily reacts with oxygen in the air to generate NO2 in the atmosphere， so NOx generally exists in the form of NO2 in the atmosphere. NO and NO2 in the air reach equilibrium through photochemical reaction and mutual conversion. When the temperature is high or there are clouds， NO2 further interacts with water molecules to form nitric acid (HNO3)， the second important acid in acid rain. In the presence of catalyst， if appropriate meteorological conditions are added， the conversion rate of NO2 to nitric acid is accelerated. Especially when NO2 and SO2 exist at the same time， they can catalyze each other and form nitric acid faster.
　　1.1.2 The Harm ofNOx
　　The atmospheric chemistry of nitrogen oxides has indirect consequences on radiative forcing， as the direct greenhouse effect through the absorption of longwave radiation of trace gases NO and NO2 is negligible.
　　The first indirect greenhouse effect is that the NOx produces tropospheric ozone. Depending on the concentration of the NOx level， there is either a formation or loss of ozone (O3) in troposphere. If the NOx less a particular threshold value， ozone is removed， while exceeding this valve it is formed， as shown in Fig. 1.1. The NOx concentration increases in regions of the troposphere which are low in NOx (primarily the regions in the tropics)， resulting in an alteration from a net O3 loss to a net O3 production. Id regions of the troposphere which are rich in nitrogen oxides， additional introduction of NOx causes the ozone concentration to become even higher. A molecule of NO2 formed near the ground in a rural， anthropogenically influenced region of the northern hemisphere leads to the production of up to 12 molecules of
　　O3 (experimental findings by [1-4]). We know that ozone is a greenhouse gas， so the NOx is one of global warming potentials (GWP) gases.
　　The second indirect greenhouse effect is that the NOx controls the atmospheric concentration of the hydroxyl radical which is the most important species of tropospheric chemistry. The hydroxyl radical mediates the removal of the most trace substances including that of methane (CH4). The increase of NOx concentration leads to the decrease of hydroxyl concentration， which increases the concentration of methane and other trace gases. This is another reason for NOx as a greenhouse gas.
　　Nitrogen oxides are converted to nitric acid and particulate nitrate (aerosol) in the atmosphere. This occurs within only a few days. In the end nitrogen oxides are converted to nitrous oxide by the soils. And N2O has a long atmospheric residence time and is recognized as a stro

Contents
1 The Harm of NOx and Its Emission 1
1.1 NOx 1
1.1.1 The Characteristic of NOx 1
1.1.2 The Harm of NOx 2
1.2 The Formation Mechanism of NOx 4
1.2.1 NOx Formation Mechanism and the Interfering Factors 4
1.2.2 Sources of NOx 6
References 8
2 NOx Emission Control Technologies (NOx Emission Abatement) 11
2.1 Introduction 11
2.1.1 Pre-combustion and Combustion Modification 11
2.1.2 Post-combustion Methods 13
2.2 SCR Process Configurations 14
2.2.1 HD-SCR Configuration 15
2.2.2 LD-SCR Configuration 17
2.2.3 TE-SCR Configuration 17
2.3 Low-Temperature SCR Catalyst 17
2.4 Low-Temperature SCR Mechanism 19
2.4.1 Eley-Rideal (E-R) Mechanism 19
2.4.2 L-H Mechanism 20
2.5 Application of Density Functional Theory (DFT) in the Study of Low Temperature SCR Catalyst 21
References 22
3 Preparation of Catalysts 25
3.1 General Process of NH3-SCR Catalysts Preparation 25
3.2 Precipitation Method 25
3.2.1 Precipitating Classical Theory 26
3.2.2 Factors Affecting Catalyst Performance in the Precipitation Method 28
3.2.3 Brief Conclusion 30
3.3 Sol-Gel Method 30
3.3.1 Fundamentals of Sol-Gel Process 31
3.3.2 Sol-Gel Methods for Preparing Supported Metals 31
3.3.3 Brief Conclusion 33
3.4 Impregnation Method 33
3.4.1 Impregnating Solution Preparation 34
3.4.2 The Influencing Factors of the Impregnation Method 35
3.4.3 Brief Conclusion 36
3.5 Hydrothermal Method 36
3.5.1 Basic Concepts of Hydrothermal Method 36
3.5.2 Principles of Hydrothermal Synthesis Methods 37
3.5.3 Brief Conclusion 38
References 39
Catalyst Characterization 41
4.1 Electron Microscopy 41
4.1.1 Scanning Electron Microscope (SEM) 41
4.1.2 Transmission Electron Microscope (TEM) 43
4.2 BET Surface Area 46
4.2.1 BET Theory 46
4.2.2 The Calculations of BET Surface Area 48
4.2.3 Drawbacks and Limitations 48
4.3 X-Ray Diffraction Techniques 49
4.3.1 Foundations of Crystallography 49
4.3.2 Powder XRD Diffraction Analysis 51
4.3.3 Application of X-Ray Diffraction in Catalyst Research 52
4.4 X-Ray Photoelectron Spectroscopy Techniques 55
4.4.1 The Features of XPS Spectra 56
4.4.2 Case Study 56
4.5 Temperature-Programmed Analysis Technique 58
4.5.1 Temperature-Programmed Desorption (TPD) 58
4.5.2 Temperature-Programmed Reduction (TPR) 60
4.6 Raman Spectroscopy 61
4.6.1 Basic Principles of Analysis 62
References 64
MnOx-Based SCR Catalyst 69
5.1 Introduction 69
5.2 Single Manganese Oxide Catalysts 70
5.2.1 Effect of Oxidation State and Crystal Structure on Catalytic Performance 70
5.2.2 Effect of Specific Surface Area and Surface Acidity on Catalytic Performance 71
5.2.3 Effect of Morphology and Exposed Crystalline Surfaces on Catalytic Performance 72
5.3 Multi-metal Manganese Oxide Catalysts 73
5.4 Supported Manganese Oxide-Based Catalysts 77
5.4.1 MnOx-Based Catalysts Supported on Ti02 78
5.4.2 MnOx-Based Catalysts Supported on AI2O3 81
5.4.3 MnOx-Based Catalysts Supported on Carbon Materials 82
References 83
Ceria-Based SCR Catalysts 87
6.1 Introduction 87
6.2 Single Ceria-Based Catalysts 88
6.2.1 Effect of Precursor and Calcination Temperature on Catalytic Performance 88
6.2.2 Effect of Preparation Method on Catalytic Performance 90
6.2.3 Effect of Morphology and Exposed Crystalline Surfaces on Catalytic Performance 92
6.3 Composite Ceria-Based Catalysts 93
6.3.1 Mn-Ce Composite Oxide System 93
6.3.2 Ce-Cu Composite Oxide System 94
6.3.3 Ce-Ti Composite Oxide System 95
6.4 Supported Ceria-Based Catalysts 97
6.4.1 CeO2 as the Support 97
6.4.2 CeO2 as the Surface Loading Component 97
References 102
Cu-Based and Fe-Based SCR Catalysts 105
7.1 Introduction 105
7.2 Cu-Based SCR Catalysts 105
7.2.1 Copper Oxide-Based Catalyst 105
7.2.2 Copper Based Molecular Sieve Catalyst 106
7.2.3 Core-Shell Structure in Copper Based NH3-SCR Catalysts 107
7.3 Fe-Based SCR Catalysts 109
7.3.1 Iron Oxide-Based Catalyst 109
7.3.2 Fe Based Molecular Sieve 112
References 112
Chemical Deactivation and Resistance of Low-Temperature SCR Catalyst 115
8.1 Introduction 115
8.2 Deactivation Mechanism of SCR Catalysts by Various Elements 116
8.2.1 S02 and H20 116
8.2.2 Alkali Metals/Alkali-Earth Metals 120
8.2.3 Heavy Metals 121
8.3 Deactivation Resistance 123
8.3.1 Resistance to SO2 or/and H2O Poisoning 123
8.3.2 Resistance to Alkali/Alkaline Metal Poisoning 125
8.3.3 Resistance to Heavy Metal Poisoning 126
References 128