The Design of a Novel Very Fast Response Analytical Facility for the Investigation of Structured Catalysts under Real Reaction Conditions

随着社会要求环境友好的化学过程将废物和能源利用率降至最低，催化是一项变得越来越重要的技术。要解决这些问题，需要更好地了解在现实条件下运行的催化剂。这项研究的目的是开发一种新的方法来研究这类催化剂和催化过程。上述许多过程导致了三维结构催化剂的发展(例如，减少各种车辆尾气的污染)。结构化催化剂的许多应用使用具有毫米通道的整体。然而，在实际工作条件下，它们内部存在显著的异质性，因此由于缺乏定量的化学分析和温度测量，过程控制和系统建模即使不是不可能，也是困难的。其结果是，这些过程经常在次优条件下工作。橡树岭国家实验室最近的研究导致了第一代毛细管进样质谱仪(SPACI-MS)的开发，该仪器能够提供时间和空间分析信息。结果表明，为了对流程进行建模和设计更好的系统，检索这些信息是多么重要。第一个版本的空间质谱仪旨在提供原理证明，然而这种简单的设备有严重的局限性：-质谱仪：质谱仪在质量形态、定量和时间分辨率方面受到限制。我们将通过安装飞行时间质谱仪来解决这个限制。它将允许以亚毫秒的时间分辨率记录整个质量范围。这将使该技术的物种形成和量化能力提高数量级。-空间分辨率：有限数量的毛细管限制了可实现的空间分辨率。为了解决这一点，我们将建立一个专用的扫描装置，它将允许毛细管在反应条件下沿着整体柱自动移动到任何地方。-温度映射：现有系统不直接在毛细管采样点进行温度测量。这是为了获得更准确的数据和更详细的动力学参数估计所必需的。为了解决这一点，我们建议将每根毛细管连接到一个250微米外径的热电偶。-采样系统：当从一个毛细管切换到另一个毛细管时，多孔阀需要很长的稳定时间。我们将通过设计一种新的阀门来克服这些限制，这种阀门将在毛细血管中产生强制流动。结果将是数据采集速度提高了一个数量级。-毛细血管的侵袭性：需要评估对毛细管大小和所探测的通道大小之间的比率的依赖以及这种毛细管的侵袭性。关键是要确定侵入性最小的条件，或者在最终的数据分析中需要考虑矫正因素。为了解决这个问题，我们建议使用DeltaP探头原理，使用每根毛细管作为压力(PITOT)探头来测量毛细血管的影响。因此，在项目的第一部分，我们将首次开发一种能够提供研究结构化催化剂所需的空间分辨率、时间响应和分析灵敏度的设备；在第二部分，我们将把新技术应用到汽车尾气催化剂的研究中，以提供准确的温度和浓度分布以及本征动力学数据；在第三部分，为了展示该技术的关键优势，我们将使用这些数据构建包括热量和质量传递项在内的完整模型。最后，该方法将进一步用于研究广泛的工业上重要的反应。

Catalysis is a technology that is becoming ever more important as society demands environmentally benign chemical processes that minimise waste and energy utilisation. To address these issues will require enhanced understanding of catalysts operating under realistic conditions. The aim of the proposed research is to develop a new methodology for studying such catalysts and catalytic processes.Many processes above resulted in the development of three dimensional structured catalysts (e.g. abatement of pollution of exhaust gases from all kinds of vehicles). Many applications of structured catalysts use monoliths with millimetric channels. However, under real working conditions, there is significant heterogeneity within them and so process control and system modelling are difficult if not impossible due to a lack of quantitative chemical analysis and temperature measurements. The result is that these processes often work under sub-optimal conditions. Recent research at the Oak Ridge National Laboratory led to the development of a first generation capillary-inlet mass spectrometer (Spaci-MS) capable of providing temporal and spatial analytical information. The results showed how important it is to retrieve this information in order to model the process and design better systems. This first version of the SpaciMS was designed to provide a proof of principle however this simple equipment has severe limitations: - The mass spectrometer: the mass spectrometer is limited in terms of mass speciation, quantification and time resolution. We shall resolve this limitation by installing a Time-Of-Flight mass spectrometer. It will allow the whole mass range to be recorded with sub-millisecond time resolution. This will provide orders of magnitude increase in the speciation and quantification capabilities of the technique. - The spatial resolution: the limited number of capillaries limits the spatial resolution that can be achieved. To address this point we will build a dedicated scan rig which will allow the capillaries to be moved automatically anywhere along the monolith under reaction conditions. - The temperature mapping: the existing system does not directly perform temperature measurement at the capillaries sampling points. This is needed to get more accurate data and more detailed estimates of kinetic parameters. To address this point, we proposed to couple each capillary with a 250 micron O.D. thermocouple. - The sampling system: the multiport valve requires long settling times when switching from one capillary to another. We shall overcome these limitations by designing a new valve that will create a forced flow through the capillaries. The outcome will be an order of magnitude improvement in the rate of data acquisition.- The invasive nature of the capillaries: the dependence on the ratio between the size of the capillary and the size of the channel probed and the invasive nature of this capillary needs to be assessed. It is crucial to define conditions where the invasive nature is minimal, or corrective factors need to be factored into the final data analysis. To address this issue, we propose to measure the effect of the capillaries by using each capillary as a pressure (Pitot) probe, using the deltaP probe principle. Therefore, in the first part of the project we will develop for the first time an apparatus that provides the spatial resolution, temporal response and analytical sensitivity required to be able to investigate structured catalysts; In the second part, we will apply the new technique to the investigation of automotive exhaust catalysts to provide accurate temperature and concentration profiles and intrinsic kinetic data; In the third part, to demonstrate the critical benefit of this technique we will use the data to construct a full model including heat and mass transfer terms. Finally, the methodology will further be used to investigate a wide range of industrially important reactions.