ERI型UZM-12ゼオライトとそのメタノールからオレフィンへの性能の合成と特徴付け
Joo Hyuck Lee1, Min Bum Park, Jun Kyu Lee
1Department of Chemical Engineering and School of Environmental Science and Engineering, POSTECH, Pohang 790-784, Korea.
Journal of the American Chemical Society
|August 26, 2010
まとめ
UZM-12ゼオライトの合成は,構造指向剤とアルカリ金属カチオンに対して敏感である. H-UZM-12のナノ結晶性は,コック形成によるメタノールからオレフィンへの触媒に悪影響を及ぼす可能性があります.
科学分野:
- マテリアルサイエンス 材料科学
- カタリシス カタリシス カタリシス
- ナノテクノロジー ナノテクノロジー
背景:
- UZM-12は,エリオナイトに関連する高シリカゼオライトです.
- ゼオライト合成には,しばしば構造指向剤 (SDA) が使用されます.
- 充電密度不一致 (CDM) アプローチはゼオライト合成に使用されます.
研究 の 目的:
- SDAとして様々な二四次アルキルアモニウムイオンを使用してUZM-12の合成を調査する.
- UZM-12結晶化におけるSDA構造とアルカリ金属カチオンの影響を調査する.
- メタノールからオレフィンへの反応における,異なる結晶石の大きさのH-UZM-12の触媒性能を評価する.
主な方法:
- 充電密度不一致 (CDM) アプローチを用いたUZM-12の合成.
- (27) Al MQ MAS NMRを使用してアルミニウムサイト偏好を決定する.
- メタノールからオレフィン (MTO) の反応におけるH-UZM-12の触媒試験.
主要な成果:
- UZM-12の結晶化は,SDAのアルキラムモニウムイオン構造とアルカリ金属カチオンに決定的に依存しています.
- アルミニウムは,UZM-12のフレームワークで優先的に高複合性のサイトを占めています.
- ナノ結晶のH-UZM-12 (≤100 nm) は,コック堆積によるMTO反応における活性と安定性が低下しています.
結論:
- SDAとアルカリ金属カチオンの寸法は,UZM-12のゼオライト合成の指示に不可欠です.
- ナノ結晶性は,MTO反応におけるH-UZM-12の触媒性能を害することがあります.
- 小さな結晶体の外面にコックが蓄積されることが,活性部位への拡散を妨げます.
関連する概念動画
01:13Olefin Metathesis Polymerization: Overview
Recently, the development of olefin metathesis polymerization advanced the field of polymer synthesis. Simply put, the reorganization of substituents on their double bonds between two olefins in the presence of a catalyst is known as the olefin metathesis reaction. The use of metathesis reaction for polymer synthesis is called olefin metathesis polymerization.
Ruthenium-based Grubbs catalyst is the most commonly used catalyst for olefin metathesis polymerization. Grubbs catalyst consists of a...
Ruthenium-based Grubbs catalyst is the most commonly used catalyst for olefin metathesis polymerization. Grubbs catalyst consists of a...
01:33Carboxylic Acids to Methylesters: Alkylation using Diazomethane
Carboxylic acids react with diazomethane in an ether solvent via alkylation at the carboxylate oxygen atom to give methyl esters of the corresponding acid with excellent yields.
02:29Ethers from Alcohols: Alcohol Dehydration and Williamson Ether Synthesis
Overview
Ethers can be prepared from organic compounds by various methods. Some of them are discussed below,
Preparation of Ethers by Alcohol Dehydration
In this method, in the presence of protic acids, alcohol dehydrates to produce alkenes and ethers under different conditions. For example, in the presence of sulphuric acid, dehydration of ethanol at 413 K yields ethoxyethane, whereas it yields ethene at 443 K.
Ethers can be prepared from organic compounds by various methods. Some of them are discussed below,
Preparation of Ethers by Alcohol Dehydration
In this method, in the presence of protic acids, alcohol dehydrates to produce alkenes and ethers under different conditions. For example, in the presence of sulphuric acid, dehydration of ethanol at 413 K yields ethoxyethane, whereas it yields ethene at 443 K.
02:35Ethers from Alkenes: Alcohol Addition and Alkoxymercuration-Demercuration
Overview
Ethers can also be prepared from alkenes through acid-catalyzed addition of alcohols and alkoxymercuration–demercuration.
Preparation of Ethers by Acid-Catalyzed Addition of Alcohol to Alkenes
The acid-catalyzed addition of alcohol to an alkene involves treating the alkene with an excess of alcohol in the presence of an acid catalyst to form an ether under suitable conditions. The hydrogen will add to the less substituted carbon so that the nucleophile can attack the more substituted...
Ethers can also be prepared from alkenes through acid-catalyzed addition of alcohols and alkoxymercuration–demercuration.
Preparation of Ethers by Acid-Catalyzed Addition of Alcohol to Alkenes
The acid-catalyzed addition of alcohol to an alkene involves treating the alkene with an excess of alcohol in the presence of an acid catalyst to form an ether under suitable conditions. The hydrogen will add to the less substituted carbon so that the nucleophile can attack the more substituted...
00:53Olefin Metathesis Polymerization: Acyclic Diene Metathesis (ADMET)
Acyclic diene metathesis polymerization or ADMET polymerization involves cross-metathesis of terminal dienes, such as 1,8-nonadiene, to give linear unsaturated polymer and ethylene. As ADMET is a reversible process, the formed ethylene gas must be removed from the reaction mixture to complete the polymerization process.
Similar to cross-metathesis, ADMET also involves the formation of metallacyclobutane intermediate by [2+2] cycloaddition of one of the double bonds of a terminal diene with...
Similar to cross-metathesis, ADMET also involves the formation of metallacyclobutane intermediate by [2+2] cycloaddition of one of the double bonds of a terminal diene with...
02:43E1 Reaction: Stereochemistry and Regiochemistry
One of the critical aspects of the E1 reaction mechanism, as also observed in E2, is the regiochemistry, with multiple regioisomers obtained as products. In the example discussed, the presence of water as a weak base favors elimination over substitution to generate two alkenes. Given that alkenes’ stability increases with the number of alkyl groups across the double bond, typically, E1 reactions lead to the Zaitsev product, for this is more substituted and stable than the Hofmann product.