在原子分散金属催化剂的结构功能关系定义中,统一性是关键:Pt/CeO的案例
Joaquin Resasco1, Leo DeRita1, Sheng Dai
1Department of Chemical Engineering , University of California Santa Barbara , Santa Barbara , California 93106 , United States.
Journal of the American Chemical Society
|December 10, 2019
概括
在二氧化 (CeO2) 支持器上低 (Pt) 负载会产生稳定,原子分散的催化剂. 较高的负载形成较不稳定的纳米粒子,影响催化转换器的性能.
科学领域:
- 不同质的催化
- 材料科学
- 表面化学
背景情况:
- 在二氧化 (CeO2) 上原子分散的 (Ptiso) 显示出有效的催化.
- 高表面积和模型Ptiso/CeO2系统之间的行为差异表明Pt协调有所不同.
- 了解地方协调对于调和这些差异至关重要.
研究的目的:
- 调和高表面积和模型Ptiso/CeO2系统的行为差异.
- 研究加载对Ptiso/CeO2催化剂的作用.
- 建立原子尺度协调和催化功能的关系.
主要方法:
- 高表面积Ptiso/CeO2催化剂在不同低负载 (重量<0.1%和重量>0.1%) 的合成.
- 催化剂可降解性,烧结性 (在0.05 bar H2中高达500°C) 和CO相互作用强度的表征.
- 与精确定义的表面科学和计算模型系统进行比较.
主要成果:
- 低Pt负载 (重量<0.1%) 产生Ptiso/CeO2,耐减少和烧结,具有最小的CO相互作用,模仿模型系统.
- 较高的Pt负荷 (>0.1%重量) 会导致具有强烈的CO相互作用和较低的烧结阻力的亚纳米Pt结构.
- 低金属载荷可以选择稳定的吸附点,导致均的原子分散.
结论:
- 低负载对于在高表面积支上实现稳定,均分散的催化剂至关重要.
- 位置均性对于将原子尺度结构与催化性能联系起来至关重要.
- 在原子分散金属催化剂的稳定性和反应性之间存在平衡,如Ptiso/TiO2比较所示.
相关概念视频
02:50Catalysis
30.0K
The presence of a catalyst affects the rate of a chemical reaction. A catalyst is a substance that can increase the reaction rate without being consumed during the process. A basic comprehension of a catalysts’ role during chemical reactions can be understood from the concept of reaction mechanisms and energy diagrams.
30.0K
02:58Crystal Field Theory - Octahedral Complexes
30.2K
Crystal Field Theory
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
30.2K
02:37Metallic Solids
20.4K
Metallic solids such as crystals of copper, aluminum, and iron are formed by metal atoms. The structure of metallic crystals is often described as a uniform distribution of atomic nuclei within a “sea” of delocalized electrons. The atoms within such a metallic solid are held together by a unique force known as metallic bonding that gives rise to many useful and varied bulk properties.
All metallic solids exhibit high thermal and electrical conductivity, metallic luster, and malleability....
All metallic solids exhibit high thermal and electrical conductivity, metallic luster, and malleability....
20.4K
02:17Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
3.8K
Catalytic hydrogenation of alkenes is a transition-metal catalyzed reduction of the double bond using molecular hydrogen to give alkanes. The mode of hydrogen addition follows syn stereochemistry.
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
The metal catalyst used can be either heterogeneous or homogeneous. When hydrogenation of an alkene generates a chiral center, a pair of enantiomeric products is expected to form. However, an enantiomeric excess of one of the products can be facilitated using an enantioselective reaction or an...
3.8K