3+-改性Co3O4的可降解性:分布的影响
Svetlana V Cherepanova1,2, Egor G Koemets1, Evgeny Yu Gerasimov1,2
1Boreskov Institute of Catalysis SB RAS, Lavrentiev Ave., 5, Novosibirsk 630090, Russia.
Materials (Basel, Switzerland)
|September 28, 2023
概括
(Al3+) 在 (Co) 氧化物中的兴奋剂影响了它们的还原行为. 在Co3O4格子内Al的分布显著改变了在降解过程中形成的减少途径和中间物种.
科学领域:
- 材料科学 材料科学 材料科学
- 催化剂是一种催化剂.
- 无机化学 无机化学 有机化学
背景情况:
- 氧化物在催化过程中至关重要,但它们的还原特性对剂敏感.
- 了解 (Al3+) 等剂的作用是定制催化剂性能的关键.
- 制备方法和烧焦温度显著影响混合金属氧化物的结构和特性.
研究的目的:
- 调查Al3+兴奋剂对Co3O4的减少行为的影响.
- 为了阐明化后Al-化Co3O4的结构变化和离子分布.
- 为了将Al分布与还原路径和中间氧化物相关联.
主要方法:
- 制备Al-doped Co3O4通过共同沉,然后在500°C和850°C进行化.
- 在现场进行X射线衍射 (XRD) 和温度编程降解 (TPR) 以研究降解过程.
- 高角环状暗场扫描传输电子显微镜 (HAADF-STEM) 与能量分散光谱 (EDS) 用于元素映射和阴子分布分析.
主要成果:
- 在Co3O4网格中包含Al3+,其分布取决于化温度.
- 500°C的化产生了一个不均的 (Co,Al) 3O4固体溶液.
- 在850°C的化导致部分分解,形成Al-贫的内部和Al-丰富的表面.
- 通过 (Co,Al) 3O4 → (Co,Al) O → Co进行降解,其中Al是稳定中间的CO (II) -Al (III) 氧化物.
- 的分布决定了减少的途径:均的固体溶液稳定了中间体,而表面丰富的导致了Co和Al物种的独立减少.
结论:
- Al3+兴奋剂通过影响阳离子分布和稳定中间氧化物,显著改变了Co3O4的减少行为.
- 化温度对于确定Al分布和随后的降解特征至关重要.
- 这些发现为Co3O4/γ-Al2O3支持的催化剂的行为提供了洞察力,影响了活性成分的性能.
相关概念视频
01:19Acid Halides to Alcohols: LiAlH4 Reduction
2.9K
Acid halides are reduced to alcohols in the presence of a strong reducing agent like lithium aluminum hydride.
The mechanism proceeds in three steps. First, the nucleophilic hydride ion attacks the carbonyl carbon of the acid halide to form a tetrahedral intermediate. Next, the carbonyl group is re-formed, and the halide ion departs as a leaving group, generating an aldehyde. A second nucleophilic attack by the hydride yields an alkoxide ion, which, upon protonation, gives a primary alcohol as...
The mechanism proceeds in three steps. First, the nucleophilic hydride ion attacks the carbonyl carbon of the acid halide to form a tetrahedral intermediate. Next, the carbonyl group is re-formed, and the halide ion departs as a leaving group, generating an aldehyde. A second nucleophilic attack by the hydride yields an alkoxide ion, which, upon protonation, gives a primary alcohol as...
2.9K
01:20Amides to Amines: LiAlH4 Reduction
4.9K
Amide reduction with strong reducing agents like lithium aluminum hydride proceeds through a nucleophilic acyl substitution to form amines. Primary, secondary, and tertiary amides yield primary, secondary, and tertiary amines, respectively.
Amide reduction requires two equivalents of the reducing agent, acting as a source of hydride ions. As shown in the figure, the reaction is initiated with a nucleophilic attack by the hydride ion at the carbonyl carbon to form a tetrahedral intermediate.
Amide reduction requires two equivalents of the reducing agent, acting as a source of hydride ions. As shown in the figure, the reaction is initiated with a nucleophilic attack by the hydride ion at the carbonyl carbon to form a tetrahedral intermediate.
4.9K
01:17Carboxylic Acids to Primary Alcohols: Hydride Reduction
3.0K
Carboxylic acids, upon reaction with strong reducing agents such as lithium aluminum hydride followed by hydrolysis, undergo reduction to form primary alcohols.
3.0K
01:15Acid Halides to Alcohols: Grignard Reaction
2.2K
Organomagnesium halides, commonly known as Grignard reagents, convert acid halides to tertiary alcohols. The reaction requires two equivalents of the Grignard reagent and proceeds via a ketone intermediate.
Grignard reagents are a source of carbanions and function as nucleophiles. The mechanism begins with the nucleophilic attack by the carbanion at the carbonyl carbon of the acid halide to form a tetrahedral intermediate. Next, the carbonyl group is re-formed, and the halide ion departs,...
Grignard reagents are a source of carbanions and function as nucleophiles. The mechanism begins with the nucleophilic attack by the carbanion at the carbonyl carbon of the acid halide to form a tetrahedral intermediate. Next, the carbonyl group is re-formed, and the halide ion departs,...
2.2K
00:55Nitriles to Amines: LiAlH4 Reduction
3.5K
Nitriles are reduced to amines in the presence of strong reducing agents like lithium aluminum hydride through a typical nucleophilic acyl substitution. The reaction requires two equivalents of the reducing agent. The reducing agent acts as a source of hydride ions.
As shown below, the mechanism involves three steps. Firstly, the hydride ion acting as a nucleophile attacks the nitrile carbon to form an anion. In the second step, a second equivalent of the hydride ion attacks the anion to...
As shown below, the mechanism involves three steps. Firstly, the hydride ion acting as a nucleophile attacks the nitrile carbon to form an anion. In the second step, a second equivalent of the hydride ion attacks the anion to...
3.5K
03:02Colors and Magnetism
11.8K
Color in Coordination Complexes
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...
When atoms or molecules absorb light at the proper frequency, their electrons are excited to higher-energy orbitals. For many main group atoms and molecules, the absorbed photons are in the ultraviolet range of the electromagnetic spectrum, which cannot be detected by the human eye. For coordination compounds, the energy difference between the d orbitals often allows photons in the visible range to be absorbed and emitted, which is seen as colors by the human...
11.8K