Porous membranes are used as catalysts for selective extraction of single components, controlled dosing of a reactant, and to intensify the contact between reactants to increase the reaction rate. The manufacture of these catalytic membrane reactors faces several challenges including the preservation of a very high surface area while ensuring mechanical stability. Depending on the application, a specific pore size, permeability, or hierarchical structure may also be desired.
Capillary suspensions are three-phase systems with a small amount (< 5 vol%) of an immiscible secondary phase added to a suspension. The secondary phase creates a strong sample spanning network due to capillary forces, which changes the material strength from fluid-like or weakly elastic to strong gel behavior. The particle network connected through capillary bridges does not collapse during debinding or sintering, and thus can serve as precursor for sintered materials with high open porosity. This process will be adapted to use highly porous, catalytically active particles. The secondary fluid has to be wisely chosen and an innovative sintering strategy has to be developed in order to avoid reduction of the total surface area or damage the surface chemistry of active particles. The aim is to create chemically activated sintered bodies for catalysis. Therefore, the bodies are formed through a 3D printing or extrusion process to achieve hierarchically structured highly porous green bodies with complex shapes.