在金属有机框架中直接测量吸附气体的再分配
Ying-Pin Chen1, Yangyang Liu, Dahuan Liu
1Department of Materials Science and Engineering, and ‡Department of Chemistry, Texas A&M University , College Station, Texas 77843, United States.
Journal of the American Chemical Society
|February 13, 2015
概括
了解金属有机框架 (MOF) 中的气体分子动力学是关键. 一种新的时间分辨率衍射方法揭示了气体在吸附和脱附周期期间如何在MOF中重新分配和相互作用.
科学领域:
- 材料科学 材料科学 材料科学
- 化学 化学 化学
- 晶体学 晶体学是指结晶学.
背景情况:
- 定制金属有机框架 (MOF) 作为吸附剂需要了解气体分子与吸附点的相互作用.
- 在MOF中吸附/脱附周期期间的动态相互作用是复杂的,并未完全理解.
- 关于MOF中的气体动力学和客分子分布的实验研究有限.
研究的目的:
- 开发一种方法来监测MOFs.内部的动态气体过程.
- 为了研究气体分子再分配和吸附和脱附过程中的相互作用.
- 了解温度和气体对气体相互作用对MOF吸附的影响.
主要方法:
- 开发了一种直接时间解析的衍射结构外 (TRDSE) 方法.
- 采用了在现场同步子粉末X射线衍射的顺序测量.
- 在MOFs的温度变化时监控气体输入,脱落和再分配.
主要成果:
- 电子密度图显示,气体分子在异质地点重新分布,而不仅仅是初级结合点.
- 气体分子在输液过程中表现出一种由热驱动的,局部到移动的机制.
- 吸附剂分离比因温度而异,受气体相互作用的影响,导致有序安排.
结论:
- 通过TRDSE方法,有效地监测MOF中的动态气体过程.
- 气体再分配和取决于温度的分区是MOF吸附的关键方面.
- 开发的方法广泛适用于用于分析吸附剂分布的晶体吸附剂.
相关概念视频
Adsorption of Gases on Solids
242
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...
242
Adsorption Isotherms I
194
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...
194
Adsorption Isotherms II
122
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...
122


