生物乙醇直接转化为异布在纳米尺寸Zn{x}Zr{y}O{z}混合氧化物上,与平衡的酸位进行直接转化
Junming Sun1, Kake Zhu, Feng Gao
1Institute for Interfacial Catalysis, Pacific Northwest National Laboratory, Richland, Washington 99352, USA.
Journal of the American Chemical Society
|June 21, 2011
概括
纳米化-混合氧化物使生物乙醇能够高产转化为异布. 这种新型催化剂抑制了不必要的反应,通过量身定制的表面化学物质实现了~83%的选择性.
科学领域:
- 催化剂是一种催化剂.
- 材料科学 材料科学 材料科学
- 化学工程是化学工程的重要组成部分.
背景情况:
- 将生物乙醇转化为异布是可持续燃料生产的关键目标.
- 基催化剂经常遭受强酸性,导致不必要的副作用和焦化.
- 开发能够选择性地控制酸性质的催化剂对于高效的生物乙醇升级至关重要.
研究的目的:
- 为了设计和合成纳米化Zn{x}Zr{y}O{z}混合氧化物.
- 为了实现直接和高产转化生物乙醇到异布.
- 阐明导致高选择性的催化机制.
主要方法:
- 合成纳米尺寸Zn{x}Zr{y}O{z}混合氧化物催化剂.
- 催化剂表面特性 (酸性和基本性) 的表征.
- 测试生物乙醇直接转化为异布的催化性能.
主要成果:
- 从生物乙醇中获得高产量 (~83%) 的异布.
- 通过添加ZnO,证明了强易斯酸性位点的选择性被动化和石上的布伦斯特酸性位点的削弱.
- 抑制了诸如生物乙醇脱水和乙聚合/化等不良反应.
- 确定了一种主要的反应途径,涉及乙醇脱,阿尔多尔凝结和转化为异布丁.
结论:
- 纳米化Zn{x}Zr{y}O{z}混合氧化物是直接将生物乙醇转化为异布的有效催化剂.
- 调整催化剂的酸性质是实现高选择性和产量的关键.
- 开发的催化剂为从生物质中获得的乙醇生产可持续的异布丁提供了一个有希望的途径.
相关概念视频
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.
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.
02:15Preparation of Alcohols via Addition Reactions
Overview
The acid-catalyzed addition of water to the double bond of alkenes is a large-scale industrial method used to synthesize low-molecular-weight alcohols. An acidic atmosphere is required to allow the hydrogen in the water molecule to act as an electrophile and attack the double bond in an alkene. The addition of a proton to the double bond creates a carbocation intermediate. The proton preferentially bonds to the less substituted end of the double bond to create a more stable carbocation...
The acid-catalyzed addition of water to the double bond of alkenes is a large-scale industrial method used to synthesize low-molecular-weight alcohols. An acidic atmosphere is required to allow the hydrogen in the water molecule to act as an electrophile and attack the double bond in an alkene. The addition of a proton to the double bond creates a carbocation intermediate. The proton preferentially bonds to the less substituted end of the double bond to create a more stable carbocation...
01:46Oxidative Cleavage of Alkenes: Ozonolysis
In ozonolysis, ozone is used to cleave a carbon–carbon double bond to form aldehydes and ketones, or carboxylic acids, depending on the work-up.
Ozone is a symmetrical bent molecule stabilized by a resonance structure.
Ozone is a symmetrical bent molecule stabilized by a resonance structure.
02:44Oxidation of Alkenes: Syn Dihydroxylation with Osmium Tetraoxide
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.
02:47Alkynes to Aldehydes and Ketones: Hydroboration-Oxidation
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.