表面相互作用和量子运动分子选用于混合金属有机框架材料上的H2和D2吸附
Banglin Chen1, Xuebo Zhao, Apipong Putkham
1Department of Chemistry, University of Texas-Pan American, Edinburg, Texas 78539, USA.
Journal of the American Chemical Society
|April 26, 2008
概括
这项研究开发了一种新的金属有机框架 (M
科学领域:
- 材料科学 材料科学 材料科学
- 化学 化学 化学
- 纳米技术 纳米技术
背景情况:
- 开发用于高效储存的先进材料对于清洁能源应用至关重要.
- 金属有机框架 (MOF) 提供可调节的多孔性和高表面积的气体吸附.
- 在超微孔的MOF中固定开放的金属位点可以增强气体结合亲和力.
研究的目的:
- 为了合成和表征一种新的混合/铜MOF (M'MOF 1) 与固定开放的金属位点.
- 为了研究M'MOF 1对H2存储的 (H2) 和 (D2) 吸附性质.
- 探索孔隙封闭和开放金属中心对吸附和动力学的影响.
主要方法:
- 合成一个混合的/铜MOF,Zn 3(BDC) 3[Cu(Pyen) ] . (DMF) 5(H 2O) 5. 在这个问题上.
- 溶解以创建具有超微孔性 (<0.56 nm) 的双模孔性结构 (M'MOF 1).
- 在低温温度 (77.3K和87.3K) 下测量H2和D2吸附同热度和动力学.
- 分析使用病毒模型和范特霍夫同位素来确定同位素热症.
- 使用双指数模型进行动力分析.
主要成果:
- M'MOF 1 呈现双模孔状结构,具有开放的铜中心,最大限度地增加了吸附剂-吸附剂相互作用.
- 在多孔材料上获得了对H2和D2吸附的最高观察到的同位素度 (12.29 ± 0.53 kJ mol-1 在零覆盖).
- 观察到量子分子选效应,由于零点能量的差异,D2的吸附动力学比H2更快.
- 在广泛的表面覆盖范围内,吸附度度仍然很高,这表明结合强.
结论:
- 在M'MOF 1中,开放的金属位点和超微孔封闭的结合导致了异常高的H 2吸附度.
- 量子效应显著影响MOF孔内的H2和D2扩散.
- M'MOF 1显示出先进储存应用的巨大潜力.
相关概念视频
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...
01:28Adsorption of Gases on Solids
Adsorption is a process where molecules, known as the adsorbates, accumulate on a surface, which is referred to as the adsorbent or substrate. Occurring at the solid-gas interface, this phenomenon is crucial in various scientific and industrial contexts. The reverse of adsorption is desorption.Two types of adsorptions exist: physical (physisorption) and chemical (chemisorption). Physisorption involves gas molecules held to the solid's surface by relatively weak intermolecular van der Waals...
01:29Adsorption Isotherms I
Adsorption isotherms are mathematical models that describe how molecules in a gas or liquid phase interact with surfaces. Two of the most common isotherm models are the Langmuir and Freundlich isotherms, which relate to Type I monolayer chemisorption. The Langmuir model is based on four key assumptions:• Adsorption cannot exceed monolayer coverage.• All surface sites are equivalent.• Molecules adsorb only at vacant sites.• There are no interactions between adsorbed molecules.Consider the...
01:25Adsorption Isotherms II
Brunauer, Emmett, and Teller (BET) introduced a theory in 1938 that modified Langmuir's assumptions to explain multilayer physical adsorption. This theory is applicable to Type II isotherms and provides a more realistic picture of adsorption processes. The BET theory assumes a uniform solid surface with localized adsorption sites, where adsorption at one site doesn't affect adsorption at neighboring sites. This theory also allows for the possibility of additional molecules being adsorbed on top...