用于氧化乙醇到二氧化碳的第三级电催化剂:使它们能够分裂C-C键
Meng Li1, David A Cullen, Kotaro Sasaki
1Department of Chemistry, Brookhaven National Laboratory, Upton, New York 11973, United States.
Journal of the American Chemical Society
|December 6, 2012
概括
研究人员发现,与和锡氧化物相结合时, (Ir) 可以在乙醇电氧化 (EOR) 中分解碳-碳键. 这一发现推进了在室温下有效的乙醇氧化到二氧化碳的方法.
科学领域:
- 电化学 电化学 电化学
- 材料科学 材料科学 材料科学
- 催化剂是一种催化剂.
背景情况:
- 在乙醇电氧化 (EOR) 到CO2中,分解碳-碳键是一个主要的挑战.
- 之前的研究发现了一种三元PtRhSnO2电催化剂,能够在室温下进行C-C键裂变.
研究的目的:
- 调查 (Ir) 是否也可以促进EOR的三元电催化剂中的C-C键分裂.
- 在SnO2纳米粒子核心上合成和表征多金属纳米岛电催化剂.
主要方法:
- 使用种子生长方法在SnO2核心上合成碳支持的纳米粒子电催化剂,并使用多金属纳米岛 (PtIr,PtRh,IrRh,PtIrRh).
- 使用各种技术进行表征,以确定构成和架构.
- 电化学研究和现场红外反射吸收光谱,以评估活性和反应中间体.
主要成果:
- 与传统的Pt/C和Pt/SnO2/C相比,一些合成的多金属/SnO2/C电催化剂表现出明显更高的EOR反应性和对CO2的选择性.
- PtIr/SnO2/C催化剂,特别是具有高Ir含量的催化剂,表现出异常的性能,包括最负的EOR发作潜力.
- 有证据表明,像Rh一样,Ir可以有效地分裂三元系统中的C-C键.
结论:
- 可以被诱导分裂C-C键,作为乙醇电氧化三元电催化剂的组成部分.
- 该PtIr/SnO2/C催化剂显示了高效的乙醇完全氧化到CO2的有希望的潜力.
相关概念视频
01:17Thermal Electrocyclic Reactions: Stereochemistry
The stereochemistry of electrocyclic reactions is strongly influenced by the orbital symmetry of the polyene HOMO. Under thermal conditions, the reaction proceeds via the ground-state HOMO.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
Selection Rules: Thermal Activation
Conjugated systems containing an even number of π-electron pairs undergo a conrotatory ring closure. For example, thermal electrocyclization of (2E,4E)-2,4-hexadiene, a conjugated diene containing two π-electron pairs, gives trans-3,4-dimethylcyclobutene.
02:35Acid-Catalyzed Dehydration of Alcohols to Alkenes
In a dehydration reaction, a hydroxyl group in an alcohol is eliminated along with the hydrogen from an adjacent carbon. Here, the products are an alkene and a molecule of water. Dehydration of alcohols is generally achieved by heating in the presence of an acid catalyst. While the dehydration of primary alcohols requires high temperatures and acid concentrations, secondary and tertiary alcohols can lose a water molecule under relatively mild conditions.
01:26Thermal and Photochemical Electrocyclic Reactions: Overview
Electrocyclic reactions are reversible reactions. They involve an intramolecular cyclization or ring-opening of a conjugated polyene. Shown below are two examples of electrocyclic reactions. In the first reaction, the formation of the cyclic product is favored. In contrast, in the second reaction, ring-opening is favored due to the high ring strain associated with cyclobutene formation.
01:33Preparation of Aldehydes and Ketones from Alcohols, Alkenes, and Alkynes
Aldehydes and ketones are prepared from alcohols, alkenes, and alkynes via different reaction pathways. Alcohols are the most commonly used substrates for synthesizing aldehydes and ketones. The conversion of alcohol to aldehyde, which involves the oxidation process, depends on the class of the alcohol used and the strength of the oxidizing agent. For instance, primary alcohol will form an aldehyde when treated with a weak oxidizing agent; however, it gets over-oxidized to a carboxylic acid in...
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...
03:08Hydroboration-Oxidation of Alkenes
In addition to the oxymercuration–demercuration method, which converts the alkenes to alcohols with Markovnikov orientation, a complementary hydroboration-oxidation method yields the anti-Markovnikov product. The hydroboration reaction, discovered in 1959 by H.C. Brown, involves the addition of a B–H bond of borane to an alkene giving an organoborane intermediate. The oxidation of this intermediate with basic hydrogen peroxide forms an alcohol.