Aligned Carbon Nanotubes as Porous Materials for Selective Gas Adsorption and Desorption

概述我们在第三个资金期所做的努力将继续旨在对高度有序的碳纳米管阵列中的气体吸附有一个坚实的了解。技术诱因是这样的阵列作为烟气中有害成分(如二氧化碳、二氧化硫、氮氧化物和硫化氢)的吸附剂的潜力，即用于气体净化。然而，在基础科学层面上，碳纳米管阵列也是研究碳材料中气体吸附的完美模型系统。我们可以通过良好控制的几何参数(管径、管间距离、长度)来重复性地制造它们，这使得它们非常适合与理论模拟研究进行比较。在第1和第2期资助结果的基础上，我们将继续使用实验技术(靶向制备、光谱表征和常压和高压下的特定吸附测量)，并结合理论方法(吸附热力学的宏正则蒙特卡罗模拟、传输过程的分子动力学和分析模型)，在分子水平上获得吸附机制的统一图景。扩大科学问题的范围和使用的方法。我们在第三个资助期的研究重点将放在：混合物的吸附。这包括为了分离和提纯过程对某些组分的吸附选择性的解释，以及对多种气体吸附中的正相互干扰和负相互干扰的理解。作为这一分主题的一部分，我们还将研究一种成分为水的混合物，因为湿度在技术应用中无处不在。带电纳米管阵列。我们的理论研究预测，碳纳米管阵列上的电荷可以调节对二氧化碳的吸附。现在，我们将在一个实验装置中尝试并验证这些预测，以测量电荷可以外部控制的电接触碳纳米管阵列的气体吸附能力。同时，还将对其他气体进行进一步的模拟。我们还将研究将电接触的碳纳米管阵列块用作静电摆动吸附/解吸装置的可能性。化学修饰的碳纳米管。我们已经证明，等离子体处理和高温CO2处理能够对碳纳米管表面进行化学修饰，有时会导致气体吸附急剧增加。这些研究将继续进行，并伴随着现实的模拟，目的是获得对单个表面基团和缺陷的吸附能力、它们的相互作用和它们的选择性的分子理解。这些联合努力的结果将被用来建议具有定制的吸附和选择性轮廓的目标表面官能化。

Summary Our efforts during funding period three will continue to be aimed at gaining a solid understanding of the adsorption of gases in highly ordered arrays of carbon nanotubes (CNTs). The technological incentive is the potential of such arrays as adsorbents for noxious components of flue gases, such as CO2, SO2, NOx and H2S, i.e. for gas purification. On a fundamental scientific level, however, CNT arrays are also perfect model systems for the investigation of gas adsorption in carbon materials. We can manufacture them reproducibly with well-controlled geometry parameters (tube diameter, intertube distance, length), which makes them ideal for comparison with theoretical simulation studies. Building on our results from funding periods 1 and 2, we will continue to use experimental techniques (targeted preparation, spectroscopic characterization and specific adsorption measurements under ambient and high pressure) in tandem with theoretical methods (grand-canonical Monte Carlo simulations of adsorption thermodynamics, molecular dynamics for transport processes, and analytical models) to obtain a unified picture of the adsorption mechanisms at the molecular level. The range of scientific questions and the methods to be used will be expanded. The specific foci of our research in funding period three will be on: Adsorption of mixtures. This includes the explanation of adsorption selectivities for certain components with a view to separation and purification processes, as well as an understanding of positive and negative mutual interference in the adsorption of multiple gases. As part of this subtopic, we will also investigate mixtures with one component being water, as humidity is omnipresent in technical applications. Charged nanotube arrays. Our theoretical studies have predicted that the adsorption of CO2 can be modulated by electrical charges placed on the CNT arrays. We will now try and verify these predictions in an experimental set-up to measure gas adsorptivity of electrically contacted CNT arrays whose charge can be externally controlled. Simultaneously, further simulations for other gases will be performed. We will also investigate the possibility of using electrically contacted blocks of CNT arrays as electrostatic swing adsorption/desorption devices. Chemically modified CNTs. We have shown that plasma treatment and high-temperature CO2 treatment are able to chemically modify the CNT surfaces, sometimes leading to drastically increased gas adsorption. These studies will be continued and accompanied by realistic simulations with the aim of obtaining a molecular understanding of the adsorption capability of individual surface groups and defects, their mutual interaction and their selectivity. The results of these combined efforts will be used to suggest target surface functionalisations with tailored adsorption and selectivity profiles.