异质结纳米复合催化剂综述
相关主题
- 1、下载文档前请自行甄别文档内容的完整性，平台不提供额外的编辑、内容补充、找答案等附加服务。
- 2、"仅部分预览"的文档,不可在线预览部分如存在完整性等问题,可反馈申请退款(可完整预览的文档不适用该条件!)。
- 3、如文档侵犯您的权益，请联系客服反馈,我们会尽快为您处理(人工客服工作时间：9:00-18:30)。
1.1. Definition of the “Synergetic Catalytic Effect” in Heterogeneous Composite Catalysts
To achieve more satisfactory catalytic performance for enhanced activity and selectivity and reduced environmentally-unfriendly side effects, multicomponent composite catalysts are the natural choices.15−21 In fact, bicomponent or multicomponent composite catalysts have attracted great attention recently in the heterogeneous catalysis field. These heterogeneous composite catalysts are generally composed of one or more catalytically active components and a functional support, in which the interaction between the catalytic components and the support materials can possibly endow the composite catalysts with much improved catalytic properties, such as significantly enhanced catalytic activity, selectivity for target product(s), chemical stability, and prolonged lifetime. The heterogeneous catalytic performance is largely dependent on the catalyst nanostructures or, in another word, processing technologies, in addition to the intrinsic physical and chemical properties of the constitutive components. Chemically processed nanomaterials, such as those synthesized by sol−gel routes, usually show greatly enhanced catalytic activity thanks to the high surface area and high density of active sites on the surface of nanoparticles, as recently reviewed by Sanchez et al.22 and Debecker et al.23 In addition to this, the more important is the possible synergetic catalytic effect in nanocomposite catalysts which was found to prevail in many nanocomposites mostly synthesized by chemical processes.22−25 The synergetic catalytic effect is here defined as a certain kind of cooperation between different components and/ or active sites in one catalyst, which results in significantly, or even strikingly, enhanced catalytic performances than the arithmetic summation of those by corresponding individual components. Synergetic catalytic effects must be present between the different catalytic components or between the catalytic component(s) and the support(s) when such an enhancement or improvement in catalytic performances, such as catalytic activity, reactant conversion, product selectivity, catalyst durability and lifetime, etc., clearly occurs, as can be found in very recent reviews22−29 in varied composite catalysts. However, since the cooperations/interactions between different catalyst components are usually complicated, the possible synergetic catalytic effects and the underlying mechanisms have not been thoroughly addressed in the literature, though the synergetic effects in multicomponent catalysts have been extensively reported in different types of reaction systems. Nevertheless, from a large amount of literature reports and also
Review
1. INTRODUCTION The advantages of heterogeneous catalysis over homogeneous one, for example, repeatable use of catalysts, easy separation of catalysts from products, etc., have been well-described in standard textbooks of catalysis. Single component heterogeneous catalysts have been extensively investigated, and some of them have been successfully applied in chemical industries.1−8 Recently, research on the single-site heterogeneous catalysts (SSHCs) on atomic and/or molecular scales is becoming increasingly interesting,9−14 in which the active centers are spatially isolated from each other and uniformly distributed over a large surface area of a porous solid, and each site has the same energy of interaction between the site and the incoming reactant. The single-site catalysis constitutes an indispensable basis for the in-depth understanding of the heterogeneous catalytic process on the atomic scale.
2159 2161
CONTENTS
1. Introduction 1.1. Definition of the “Synergetic Catalytic Effect” in Heterogeneous Composite Catalysts 1.2. Scope of the Present Review 2. Synthesis of Nanocomposite Catalysts Focused on Mesostructured Composites with a Crystallized Framework 2.1. General Description of Chemical Routes for Synthesizing Nanocomposite Catalysts 2.2. Soft Templating Routes for the Mesoporous Oxides, Mesostructured Zeolites, and Nanocomposites 2.3. Replication Routes for Crystallized Mesoporous Oxides and Binary Mesoporous Composites 2.4. Template-free Routes for Mesoporous Metal Oxides and Composites 2.5. Postencapsulation Routes for the GuestLoaded Mesoporous Composites 3. Synergetic Catalytic Effects 3.1. One Component Activation by the Other between Two Catalytic Components 3.1.1. Synergetic Effect Proposals 3.1.2. CO Oxidation by Mesoporous CuO/CeO2 Composite Catalysts via Strong Metal− Semiconductor Interaction (SMSI) 3.1.3. Methanol Synthesis by Cu/ZnO-Based Catalysis via Strong Metal−Semiconductor Interaction (SMSI) 3.1.4. Suzuki/Heck C−C Coupling by Mesostructured Pd/NiFe2O4 Composite Catalysts 3.1.5. Selective Oxidation of Organics by Au/ TiO2 and Au/CeO2 Nanocomposite Catalysts 3.1.6. Organics Degradation by Au/TiO2, TiO2/ Carbon, and TiO2/Semiconductor Nanocomposite Photocatalysts 3.2. Successive Catalytic Functioning of Two Components in Multistep Reactions
2150
2151
2153
2156 2158
2139
Received: November 18, 2011 Published: November 28, 2012
dx.doi.org/10.1021/cr3002752 | Chem. Rev. 2013, 113, 2139−2181
Chemical Reviews
Review pubs.acs.org/CR
On the Synergetic Catalytic Effect in Heterogeneous Nanocomposite Catalysts
Jianlin Shi*
State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050, People’s Republic of China; Department of Materials Science and Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai 200233, People’s Republic of China; and National Engineering Research Center for Nanotechnology, 28 East Jiangchuan Road, Shanghai 200241, People’s Republic of China
© 2012 American Chemical Society
2140 2140 2140
2162
2165 2165 2166 2167
2141 2141
2142
2169 2169
2143 2144 2144 2146 2146 2146
2170
2171 2172
2147
2172 2173 2174 2175 2175 2175 2175 2176 2176
3.2.1. Synergetic Effect Proposals 3.2.2. Henry and Adol Condensation Reactions by Mesoporous Acid−Base Catalysts 3.2.3. Dye Degradation by Fe-Doped Mesoporous Zeolite 3.2.4. Ammonia Selective Catalytic Oxidation (SCO) to Nitrogen by a Mesostructured CuO/RuO2 Composite 3.3. Degradation Prevention of the Main Catalyst(s) by Secondary Component(s) for Sustained Catalytic Reactions 3.3.1. Synergetic Effect Proposals 3.3.2. H2 Electro-oxidation by Mesostructured Pt/WO3 Composite Catalysts 3.3.3. Methanol Electro-oxidation by Mesostructured Pt/WO3 Composite Catalysts 3.4. Reactant Storage/Release by the Catalytic Assistants in Multireactant Redox Reactions Catalyzed by Tricomponent Catalysts 3.4.1. Synergetic Effect Proposal 3.4.2. Oxygen Storage/Release in Three Way Catalysis for Automobile Exhaust Purification 3.4.3. Promoted Redox Reaction between CO and NO and between NO and C3H6 by a Tricomponent Catalyst with an Oxygen Storage Support 4. Further Discussions: Role Fra Baidu bibliotekf Interface and Mesostructure in Synergetic Catalytic Effects 4.1. Role of Interface Formation and Contact Angle between Components in the Synergetic Catalytic Effects 4.2. Advantages of Mesostructured Composites for the Synergetic Effects 5. Conclusions and Outlook Author Information Corresponding Author Notes Biography Acknowledgments References 2158
To achieve more satisfactory catalytic performance for enhanced activity and selectivity and reduced environmentally-unfriendly side effects, multicomponent composite catalysts are the natural choices.15−21 In fact, bicomponent or multicomponent composite catalysts have attracted great attention recently in the heterogeneous catalysis field. These heterogeneous composite catalysts are generally composed of one or more catalytically active components and a functional support, in which the interaction between the catalytic components and the support materials can possibly endow the composite catalysts with much improved catalytic properties, such as significantly enhanced catalytic activity, selectivity for target product(s), chemical stability, and prolonged lifetime. The heterogeneous catalytic performance is largely dependent on the catalyst nanostructures or, in another word, processing technologies, in addition to the intrinsic physical and chemical properties of the constitutive components. Chemically processed nanomaterials, such as those synthesized by sol−gel routes, usually show greatly enhanced catalytic activity thanks to the high surface area and high density of active sites on the surface of nanoparticles, as recently reviewed by Sanchez et al.22 and Debecker et al.23 In addition to this, the more important is the possible synergetic catalytic effect in nanocomposite catalysts which was found to prevail in many nanocomposites mostly synthesized by chemical processes.22−25 The synergetic catalytic effect is here defined as a certain kind of cooperation between different components and/ or active sites in one catalyst, which results in significantly, or even strikingly, enhanced catalytic performances than the arithmetic summation of those by corresponding individual components. Synergetic catalytic effects must be present between the different catalytic components or between the catalytic component(s) and the support(s) when such an enhancement or improvement in catalytic performances, such as catalytic activity, reactant conversion, product selectivity, catalyst durability and lifetime, etc., clearly occurs, as can be found in very recent reviews22−29 in varied composite catalysts. However, since the cooperations/interactions between different catalyst components are usually complicated, the possible synergetic catalytic effects and the underlying mechanisms have not been thoroughly addressed in the literature, though the synergetic effects in multicomponent catalysts have been extensively reported in different types of reaction systems. Nevertheless, from a large amount of literature reports and also
Review
1. INTRODUCTION The advantages of heterogeneous catalysis over homogeneous one, for example, repeatable use of catalysts, easy separation of catalysts from products, etc., have been well-described in standard textbooks of catalysis. Single component heterogeneous catalysts have been extensively investigated, and some of them have been successfully applied in chemical industries.1−8 Recently, research on the single-site heterogeneous catalysts (SSHCs) on atomic and/or molecular scales is becoming increasingly interesting,9−14 in which the active centers are spatially isolated from each other and uniformly distributed over a large surface area of a porous solid, and each site has the same energy of interaction between the site and the incoming reactant. The single-site catalysis constitutes an indispensable basis for the in-depth understanding of the heterogeneous catalytic process on the atomic scale.
2159 2161
CONTENTS
1. Introduction 1.1. Definition of the “Synergetic Catalytic Effect” in Heterogeneous Composite Catalysts 1.2. Scope of the Present Review 2. Synthesis of Nanocomposite Catalysts Focused on Mesostructured Composites with a Crystallized Framework 2.1. General Description of Chemical Routes for Synthesizing Nanocomposite Catalysts 2.2. Soft Templating Routes for the Mesoporous Oxides, Mesostructured Zeolites, and Nanocomposites 2.3. Replication Routes for Crystallized Mesoporous Oxides and Binary Mesoporous Composites 2.4. Template-free Routes for Mesoporous Metal Oxides and Composites 2.5. Postencapsulation Routes for the GuestLoaded Mesoporous Composites 3. Synergetic Catalytic Effects 3.1. One Component Activation by the Other between Two Catalytic Components 3.1.1. Synergetic Effect Proposals 3.1.2. CO Oxidation by Mesoporous CuO/CeO2 Composite Catalysts via Strong Metal− Semiconductor Interaction (SMSI) 3.1.3. Methanol Synthesis by Cu/ZnO-Based Catalysis via Strong Metal−Semiconductor Interaction (SMSI) 3.1.4. Suzuki/Heck C−C Coupling by Mesostructured Pd/NiFe2O4 Composite Catalysts 3.1.5. Selective Oxidation of Organics by Au/ TiO2 and Au/CeO2 Nanocomposite Catalysts 3.1.6. Organics Degradation by Au/TiO2, TiO2/ Carbon, and TiO2/Semiconductor Nanocomposite Photocatalysts 3.2. Successive Catalytic Functioning of Two Components in Multistep Reactions
2150
2151
2153
2156 2158
2139
Received: November 18, 2011 Published: November 28, 2012
dx.doi.org/10.1021/cr3002752 | Chem. Rev. 2013, 113, 2139−2181
Chemical Reviews
Review pubs.acs.org/CR
On the Synergetic Catalytic Effect in Heterogeneous Nanocomposite Catalysts
Jianlin Shi*
State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, 1295 Dingxi Road, Shanghai 200050, People’s Republic of China; Department of Materials Science and Engineering, East China University of Science and Technology, 130 Meilong Road, Shanghai 200233, People’s Republic of China; and National Engineering Research Center for Nanotechnology, 28 East Jiangchuan Road, Shanghai 200241, People’s Republic of China
© 2012 American Chemical Society
2140 2140 2140
2162
2165 2165 2166 2167
2141 2141
2142
2169 2169
2143 2144 2144 2146 2146 2146
2170
2171 2172
2147
2172 2173 2174 2175 2175 2175 2175 2176 2176
3.2.1. Synergetic Effect Proposals 3.2.2. Henry and Adol Condensation Reactions by Mesoporous Acid−Base Catalysts 3.2.3. Dye Degradation by Fe-Doped Mesoporous Zeolite 3.2.4. Ammonia Selective Catalytic Oxidation (SCO) to Nitrogen by a Mesostructured CuO/RuO2 Composite 3.3. Degradation Prevention of the Main Catalyst(s) by Secondary Component(s) for Sustained Catalytic Reactions 3.3.1. Synergetic Effect Proposals 3.3.2. H2 Electro-oxidation by Mesostructured Pt/WO3 Composite Catalysts 3.3.3. Methanol Electro-oxidation by Mesostructured Pt/WO3 Composite Catalysts 3.4. Reactant Storage/Release by the Catalytic Assistants in Multireactant Redox Reactions Catalyzed by Tricomponent Catalysts 3.4.1. Synergetic Effect Proposal 3.4.2. Oxygen Storage/Release in Three Way Catalysis for Automobile Exhaust Purification 3.4.3. Promoted Redox Reaction between CO and NO and between NO and C3H6 by a Tricomponent Catalyst with an Oxygen Storage Support 4. Further Discussions: Role Fra Baidu bibliotekf Interface and Mesostructure in Synergetic Catalytic Effects 4.1. Role of Interface Formation and Contact Angle between Components in the Synergetic Catalytic Effects 4.2. Advantages of Mesostructured Composites for the Synergetic Effects 5. Conclusions and Outlook Author Information Corresponding Author Notes Biography Acknowledgments References 2158