Rh/Al2O3におけるRh種のダイナミックな行動 三方向触媒反応中のモデル触媒: オペランドX線吸収スペクトロスコピー研究
Hiroyuki Asakura1,2, Saburo Hosokawa1,2, Toshiaki Ina3
1Elements Strategy Initiative for Catalysts & Batteries (ESICB), Kyoto University , 1-30 Goryo-Ohara, Nishikyo-ku, Kyoto 615-8245, Japan.
Journal of the American Chemical Society
|December 12, 2017
まとめ
この研究は,三方向反応中の触媒におけるダイナミックなRh種の振る舞いを明らかにしています. オペラントX線吸収スペクトロスコーピ (XAS) は,変化する大気下での明確な表面変化と再酸化プロセスを示した.
科学分野:
- 異質な触媒
- 材料科学
- 化学反応工学
背景:
- 活性金属種のダイナミクスを理解することは,触媒の設計に不可欠です.
- 三方向触媒 (TWC) は自動車の排気処理に不可欠です.
- ロジウム (Rh) はTWCの重要な成分ですが,反応条件下での行動は複雑です.
研究 の 目的:
- 三方向触媒反応中のRh/Al2O3触媒におけるRh種のダイナミックな振る舞いを調査する.
- Rhの表面再配置,還元,酸化プロセスを解明する.
- ダイナミックな触媒プロセスを研究するためのオペラントX線吸収光譜 (XAS) の有用性を実証する.
主な方法:
- オペランド時間解像度の速いX線吸収スペクトロスコーピー (XAS) 測定
- 反応モニタリングのためにマイクロガスクロマトグラフ,NOXメーター,および四極質量スペクトロメーターを使用した.
- SPring-8シンクロトロン装置 (BL01B1) で行われた測定
主要な成果:
- 還元性大気と酸化大気間の切り替え時に Rh 種の異なる表面再配置行動が観察されました.
- ランダムな還元過程とRhの自己触媒的酸化過程を特定した.
- ガス相反応モニタリングとスペクトロスコピクデータを相関させました.
結論:
- この研究は,TWCにおけるRh種の複雑なダイナミックな振る舞いを強調しています.
- オペランドXASは 活性金属部位の動的変化を理解するための強力な技術です
- この研究は,触媒の無効化と再生メカニズムに関する洞察を提供します.
さらに関連する動画
関連する概念動画
02:44Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide
13.0K
Alkenes are converted to 1,2-diols or glycols through a process called dihydroxylation. It involves the addition of two hydroxyl groups across the double bond with two different stereochemical approaches, namely anti and syn. Dihydroxylation using osmium tetroxide progresses with syn stereochemistry.
13.0K
02:50Catalysis
30.8K
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.
30.8K
01:11Radical Reactivity: Overview
2.8K
Radicals, the highly reactive species, gain stability by undergoing three different reactions. The first reaction involves a radical-radical coupling, in which a radical combines with another radical, forming a spin‐paired molecule. The second reaction is between a radical and a spin‐paired molecule, generating a new radical and a new spin‐paired molecule. The third reaction is radical decomposition in a unimolecular reaction, forming a new radical and a spin‐paired...
2.8K
02:17Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
3.9K
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...
3.9K
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
9.1K
Introduction
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
Like alkenes, alkynes can be reduced to alkanes in the presence of transition metal catalysts such as Pt, Pd, or Ni. The reaction involves two sequential syn additions of hydrogen via a cis-alkene intermediate.
9.1K
02:47Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
21.4K
Introduction
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
One of the convenient methods for the preparation of aldehydes and ketones is via hydration of alkynes. Hydroboration-oxidation of alkynes is an indirect hydration reaction in which an alkyne is treated with borane followed by oxidation with alkaline peroxide to form an enol that rapidly converts into an aldehyde or a ketone. Terminal alkynes form aldehydes, whereas internal alkynes give ketones as the final product.
21.4K