A Scalable Preparation Method for SILP and SCILL Ionic Liquid Thin-Film Materials

Supported ionic liquid phase (SILP) catalysts consist of a homogeneous catalyst that is dissolved in an ionic liquid and dispersed on a porous support material. This immobilization technique yields solid catalysts that can be applied in continuous gas phase processes. Recently, several successful applications have been presented that could possibly lead to a commercialization of this promising class of novel materials. The state-of-the-art preparation method uses an incipient wetness-type impregnation of the support material by a solution of catalyst, ionic liquid, and a helper solvent, followed by subsequent removal of the helper solvent in vacuo. Typically, this removal is carried out in a rotary evaporator, thus being limited in batch size. Similarly, the so-called supported catalysts with ionic liquid layer (SCILL) consist of an ionic liquid layer on top of a traditional heterogeneous catalyst, which can be prepared in a similar way. In this work, a novel preparation method for SILP catalysts is presented that is scalable for larger batches, as required for industrial use. Different types of support materials such as powders, spheres, agglomerates, and extrudates were successfully impregnated by the novel fluidized-bed impregnation method and the distribution of the ionic liquid and catalyst was analyzed by scanning electron microscopy with energy-dispersive X-ray spectroscopy measurements.