在选择性催化氧化具有高N2选择性的氨中,可再生催化系统的发展
Haifeng Wang1,2, Toru Murayama1,2,3, Tamao Ishida1,2
1Department of Applied Chemistry for Environment, Graduate School of Urban Environmental Sciences, Tokyo Metropolitan University, 1-1 Minami-Osawa, Hachioji, Tokyo 192-0397, Japan.
ACS applied materials & interfaces
|April 4, 2024
概括
这项研究引入了一种可再生的催化系统,用于氧化氨的氧化,在上使用银. 高分散的白银催化剂通过聚合和再分散的循环保持高选择性,提供可持续的工业解决方案.
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.
- 化学工程是化学工程的重要组成部分.
背景情况:
- 支持的贵金属催化剂对于工业过程至关重要,但会受到聚合的影响,降低效率并需要频繁更换.
- 由于金属颗粒聚合导致的催化剂失活是异质催化剂的一个重大挑战.
- 开发强大且可再生的催化剂对于可持续的工业应用至关重要.
研究的目的:
- 展示使用银/用于选择性催化氧化氨 (NH3-SCO) 的可再生催化系统.
- 为了研究高度分散的银 (Ag HD) 催化剂的聚合-分散行为.
- 为工业应用建立一个具有成本效益和可持续的催化剂解决方案.
主要方法:
- 用于选择性催化氧化氨的Ag/Al2O3催化剂.
- 采用现场传输电子显微镜 (TEM),原子分辨率高角度环状暗场扫描传输电子显微镜 (HAADF-STEM) 和X射线吸收光谱 (XAS) 进行表征.
- 在现场应用扩散反射红外里埃变换光谱 (DRIFTS) 来研究反应中间体.
主要成果:
- 在5个聚合和再分散周期后,Ag HD催化剂在80%的NH3转换下保持了90%以上的N2选择性,在100%的NH3转换下保持了80%以上的N2选择性.
- 催化剂在10个循环的Ar处理后,在100%的NH3转换下维持了超过98%的N2选择性.
- 在H2降解和在空气中化后重新分散到Ag HD状态下,证明可逆聚合成Ag纳米粒子 (Ag NP).
结论:
- 开发的"可再生的催化系统"有效地克服了贵金属催化剂失活的挑战.
- 在现场氧化分散Ag NP再生Ag HD催化剂,保持高性能.
- 该研究为工业催化工艺,特别是NH3-SCO.提供了一种可持续且具有成本效益的方法.
相关概念视频
Catalysis
26.9K
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.
26.9K
Preparation of Amines: Alkylation of Ammonia and Amines
3.3K
Alkylation is one of the methods used to prepare amines. Direct alkylation of ammonia or a primary amine with an alkyl halide gives polyalkylated amines along with a quaternary ammonium salt through successive SN2 reactions. This process of making the quaternary salt through the direct alkylation method is called exhaustive alkylation.
Each alkylation step makes the nitrogen center more nucleophilic, which triggers successive alkylations until a quaternary ammonium salt is formed. Considering...
Each alkylation step makes the nitrogen center more nucleophilic, which triggers successive alkylations until a quaternary ammonium salt is formed. Considering...
3.3K
Preparation of Amines: Reduction of Oximes and Nitro Compounds
3.6K
Oximes can be reduced to primary amines using catalytic hydrogenation, hydride reduction, or sodium metal reduction. The reduction of aliphatic and aromatic nitro compounds to primary amines takes place by either catalytic hydrogenation or by using active metals like Fe, Zn, and Sn in the presence of an acid.
Though catalytic hydrogenation can reduce nitrobenzenes, the reduction is nonselective in the presence of other functional groups. For instance, if nitrobenzene contains an aldehyde group,...
Though catalytic hydrogenation can reduce nitrobenzenes, the reduction is nonselective in the presence of other functional groups. For instance, if nitrobenzene contains an aldehyde group,...
3.6K
Reduction of Alkenes: Asymmetric Catalytic Hydrogenation
3.3K
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...
3.3K
Preparation of Amines: Reductive Amination of Aldehydes and Ketones
2.8K
Carbonyl compounds and primary amines undergo reductive amination first to produce imines, followed by secondary amines in the same reaction mixture, using selective reducing agents like sodium cyanoborohydride or sodium triacetoxyborohydride. Reductive amination produces different degrees of substitution of amines depending on the starting amine substrate.
2.8K
2° Amines to N-Nitrosamines: Reaction with NaNO2
4.2K
Secondary amines react with nitrous acid to form N-nitrosamines, as depicted in Figure 1. Nitrous acid, a weak and unstable acid, is formed in situ from an aqueous solution of sodium nitrite and strong acids, such as hydrochloric acid or sulfuric acid, in cold conditions. In the presence of an acid, the nitrous acid gets protonated. The subsequent loss of water results in the formation of the electrophile known as nitrosonium ion.
4.2K


