A novel method to determine the adsorption of water vapor on porous solids and supported ionic liquids by electrical sensors

离子液体在蒸发和分解方面的热稳定性对于纯的和负载的离子液体（IL）的应用是重要的。在即将完成的两个PI的联合DFG项目的过程中，已经成功地开发了电传感器，通过基于射频（RF）的方法检测离子液体的孔隙填充度。利用这种方法，可以测量由蒸发和热分解引起的质量损失。在Pd-SCILL-催化剂（具有离子液体层的固体催化剂）上丁二烯选择性加氢为丁烯的操作过程中，这也是可能的。在应用新研究项目中，这是第一个项目的延续，有前途的RF方法现在将被转移到操作中测量水蒸气在多孔固体和多孔固体上负载的离子液体上的吸附。这对于通过吸附干燥气体以及对于在催化中使用负载的离子液体通常是重要的。如果可能的话，吸附过程应在吸附器（固定床）中沿轴向空间分辨地监测。非常初步的实验表明，对于纯多孔固体以及涂有IL的多孔固体，水蒸气的吸附和解吸都可以通过基于射频的方法来测量。拟议项目的最终目标是开发一种新的电气方法，以确定吸附剂的水负荷，无接触，在operando和空间解决。将研究纯多孔二氧化硅以及涂覆有IL的二氧化硅。在后一种情况下，同时测定水负载和离子液体的孔隙填充度也是该项目的目标。最后，这些研究的结果还应应用于确定水（蒸气）对SCILL-催化剂（即负载在二氧化硅上的以钯作为活性金属的IL [DMIM][CH 3]）的活性和选择性的影响。作为一个模型反应，丁二烯选择性氢化为丁烯的反应应该再次使用。在项目结束时，应该开发一个模型，该模型可以定量解释射频信号作为输入参数（水暴露，温度）的函数，并从射频信号中推导出空间分辨的水负荷。

The thermal stability of ionic liquids with regard to evaporation and decomposition is important for the application of pure and supported ionic liquids (ILs). In the course of the soon-finished joint DFG-projects of both PIs, electrical sensors have been successfully developed to detect the pore filling degree of ionic liquids by a radio frequency-based (RF-based) method. By means of this method, the mass loss by evaporation and thermal decomposition can be measured. This was also possible in operando during the selective hydrogenation of butadiene to butene on a Pd-SCILL-catalyst (solid catalyst with ionic liquid layer).Within the applied new research project, which is a continuation of the first project, the promising RF-method shall now be transferred to measure in operando the adsorption of water vapor on porous solids and ionic liquids supported on porous solids. This is in general important for drying of gases by adsorption as well as for the use of supported ionic liquids in catalysis. If possible, the adsorption process should be monitored space-resolved in axial direction in an adsorber (fixed bed).Very preliminary experiments show that the ad- and desorption of water vapor can be measured by the radio frequency-based method both for pure porous solids as well as for porous solids coated with an IL. The ultimate goal of the proposed project is the development of a new electrical method to determine the water load of adsorption agents contact-free, in operando, and space-resolved. Pure porous silica as well as silica coated with an IL will be investigated. In the latter case, the simultaneous determination of the water load and the pore filling degree with the ionic liquid is also a goal of the project. Finally, the results of these investigations should also be applied to determine the influence of water (vapor) on the activity and selectivity of a SCILL-catalyst, namely the IL [DMIM][DMP] supported on silica with palladium as active metal. As a model reaction, the selective hydrogenation of butadiene to butene should again be used.At the end of the project, a model should have been developed that allows to quantitatively explain the radio frequency signals as a function of the input parameters (exposure of water, temperature) and that derives the water load spatially resolved from the RF signals.