ニッケル電触媒を用いた高触媒率の水素生成には,ペンダントアミン1つを含む7基のサイクルディホスフィンリガンドを含むニッケル電触媒を用いる
Michael P Stewart1, Ming-Hsun Ho, Stefan Wiese
1Center for Molecular Electrocatalysis, Physical Sciences Division, Pacific Northwest National Laboratory, P.O. Box 999, K2-57, Richland, Washington 99352, USA.
Journal of the American Chemical Society
|February 7, 2013
まとめ
サイクルディホスフィンリガンドを搭載した新しいニッケル電触媒は,水素を効率的に生成します. 最適な性能は,触媒のマッチングによって達成されます.
科学分野:
- 有機金属化学 有機金属化学
- エレクトロカタリシス.
- 水素生産の水素生産について
背景:
- ニッケルベースの複合体は,電解触媒の応用のために研究されています.
- 水素生産のための効率的な触媒の開発は,持続可能なエネルギーにとって極めて重要です.
- リガンドの設計は,触媒の活性と安定性を調節する上で重要な役割を果たします.
研究 の 目的:
- 7つ構成のサイクルディホスフィンリガンドを備えた新しいニッケルベースの電解剤を合成し,特徴づけること.
- 水素生産のためのこれらの複合体の電気触媒活性を評価する.
- 触媒性能を制御する構造活動関係を理解する.
主な方法:
- 1-パラ-X-フェニル-3,6-トリフェニル-1-アザ-3,6-ディフォスファサイクロヘプタンリガンドによるNiベースの複合体の合成と特徴付け.
- 複合体の分子構造と幾何学を決定するX線 difrraction研究.
- 水素進化の触媒活性を評価するための電気化学測定,ターンオーバー周波数決定を含む.
- 反応機構を明らかにし,触媒設計を最適化するための計算研究.
主要な成果:
- 合成された[Ni(7P(Ph) 2N(C6H4X)) 2)(BF4) 2複合体は,正方形の平面幾何学を示しています.
- これらの複合体は,水素生成のための効率的な電気触媒であり,アセトニトリルでは27,000s−1までの回転周波数を持つ.
- 添加された水は触媒を大幅に加速し,周回頻度は96,000s−1.1に達します.
- 計算による研究は,陽子化されたペンダントアミンのpKaが酸のpKaと一致するときに最適な触媒速度を達成することを明らかにしました.
結論:
- 合成されたニッケル複合体は,水素生産のための非常に効果的な電気触媒です.
- リンガンドの設計,特に置換物の電子提供特性とその結果となるpKaは,触媒効率の最適化に不可欠です.
- 触媒と陽子源の間のpKaの正確なマッチングは,高い水素進化率を達成するために不可欠です.
- 研究された複合体では,エンドプロトン化同位体形成が好まれ,H2生成のための金属の中心との近接を促進します.
さらに関連する動画
12:08Catalytic Reactions at Amine-Stabilized and Ligand-Free Platinum Nanoparticles Supported on Titania During Hydrogenation of Alkenes and Aldehydes
Published on: June 24, 2022
10:57Synthesis and Performance Characterizations of Transition Metal Single Atom Catalyst for Electrochemical CO2 Reduction
Published on: April 10, 2018
関連する概念動画
02:50Catalysis
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.
02:17Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
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...
02:13Reduction of Alkenes: Catalytic Hydrogenation
Alkenes undergo reduction by the addition of molecular hydrogen to give alkanes. Because the process generally occurs in the presence of a transition-metal catalyst, the reaction is called catalytic hydrogenation.
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the surface of...
Metals like palladium, platinum, and nickel are commonly used in their solid forms — fine powder on an inert surface. As these catalysts remain insoluble in the reaction mixture, they are referred to as heterogeneous catalysts.
The hydrogenation process takes place on the surface of...
02:24Reduction of Alkynes to cis-Alkenes: Catalytic Hydrogenation
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.
01:22Heterogeneous Catalysis
Heterogeneous catalysis involves a catalyst in a different phase from the reactants. It is a process where the catalyst and the reactants are in distinct phases, typically solid and gas or liquid.Most heterogeneous catalysts are metals, metal oxides, or acids. The list includes transition metals like iron (Fe), cobalt (Co), nickel (Ni), palladium (Pd), platinum (Pt), chromium (Cr), manganese (Mn), tungsten (W), silver (Ag), and copper (Cu). These metals possess partially vacant d orbitals that...
01:28Reduction of Benzene to Cyclohexane: Catalytic Hydrogenation
Unlike the easy catalytic hydrogenation of an alkene double bond, hydrogenation of a benzene double bond under similar reaction conditions does not take place easily. For example, in the reduction of stilbene, the benzene ring remains unaffected while the alkene bond gets reduced. Hydrogenation of an alkene double bond is exothermic and a favorable process. In contrast, to hydrogenate the first unsaturated bond of benzene, an energy input is needed; that is, the process is endothermic. This is...