Operando monitoring of Supported Ionic Liquid Phase (SILP) catalysts by microwave-based methods exemplarily investigated for the water gas shift reaction

固定化离子液体(ILS)是一种极具吸引力的催化材料，例如，负载型离子液体(SILP)的概念是将含有均相催化剂的离子液体固定在固体载体上。应用的重点是水煤气变换(WGS)反应。对于具有Ru-SILP催化剂的WGS，载体的孔填充度和催化剂在离子液体中的浓度对有效活性的影响已经被证明，但还不完全清楚。通常，均相催化剂的稳定性取决于原料气。因此，通过用H2还原金属络合物，可以观察到Ru纳米颗粒的形成。在工艺过程中，催化剂的失活通常只能通过测量活性的降低来观察。仅对催化剂(表面、组成等)进行后续研究允许推断这一情况的可能原因。在设想的项目中，将首次在工艺条件下研究用于WGS反应的SILP催化剂的基于非接触式射频(RF)的操纵面状态监测。之所以选择WGS反应，是因为它的重要性(例如NH3合成)，而且我们已经在SILP系统方面获得了良好的经验。初步研究表明，RF法可用于SILP催化剂的状态诊断。因此，总体目标是确定非接触式射频方法是否适用于连续工艺监测以及在多大程度上适用于连续工艺监测。计划中的调查基于三个支柱：1)Jess小组关于WGS与SILP反应的初步工作，2)MoOS小组在废气催化剂射频状态监测方面的经验，以及3)关于SILP气体干燥系统射频水负荷检测的联合工作。在本项目中，系统地研究了含有IL和催化剂的载体的介电材料性能随IL的孔填充度和催化剂负载量的变化。温度的影响也要考虑在内。还应该阐明纯IL的介电性能与SILP的介电性能有多大的不同，以及催化材料对介电材料的介电性能有多大的影响。WGS反应的伴随动力学研究是必不可少的。射频方法最终将被用来建立催化“性能”的下降与射频共振参数变化之间的关系。这将用于监测SILP催化剂的操纵性。对化学反应过程及其相互作用对介电材料参数的模拟也进行了展望。这种联系将允许从测量的RF数据中以空间和时间分辨率来理解和定量描述反应室中的过程。

Immobilized ionic liquids (ILs) are attractive materials for catalysis, e.g., for the Supported Ionic Liquid Phase (SILP) concept, where the IL that contains a homogeneous catalyst is immobilized on a solid support. The application focuses on the water gas shift (WGS) reaction. For WGS with a Ru-SILP catalyst, the influence of the pore filling degree of the support and the catalyst concentration in the IL on the effective activity has been demonstrated, but is only incompletely understood. Often, the stability of the homogeneous catalyst depends on the feed gas. Thus, Ru nanoparticle formation was observed by the reduction of the metal complex with H2. In technical processes, catalyst deactivation is often observed only by measuring the decrease in activity. Only subsequent investigations of the catalyst (surface, composition, etc.) allow to deduce possible reasons for this. In the envisaged project, the contactless radio frequency (RF)-based operando state monitoring of SILP catalysts for the WGS reaction will be investigated for the first time under process conditions. The WGS reaction was selected, because of its significance (e.g. NH3 synthesis) and because we have already gained good experience with SILP systems. Preliminary studies show that the RF method can be used to diagnose the state of the SILP catalyst. The overall objective is therefore to determine whether and to what extent the non-contact RF method is suitable for continuous process monitoring. The planned investigations base on three pillars: 1) on the preliminary work of the Jess group on the WGS reaction with SILP, 2) on the experience of the Moos group on RF-based state monitoring of exhaust gas catalysts, and 3) on joint work on RF-based water loading detection of SILP gas drying systems. In the project, the dielectric material properties of the support that contains the IL and the catalyst are to be systematically investigated as a function of the pore filling degree and the catalyst loading of the IL. The influence of temperature is also to be taken into account. It should also be clarified how much the dielectric properties of the pure IL differ from those of the SILP and how much the catalytic material influences the dielectric material properties. Accompanying kinetic studies of the WGS reaction are essential. The RF method will eventually be used to establish a relationship between the decrease in catalytic "performance" and changes in RF resonance parameters. This will be used to monitor the SILP catalyst operando. Modeling of the chemical reaction processes and their interactions on the dielectric material parameters is also envisioned. This linkage would allow the processes in the reaction chamber to be understood and quantitatively described with spatial and temporal resolution from the measured RF data.