Development of a manufacturing process for Binder Jet 3D printed porous Al2O3 supports used in heterogeneous catalysis

Abstract

A complete preparation route for the direct 3D printing of Al2O3 supports made from boehmite and bayerite was established using the Binder Jetting technology. The application of the ceramic supports as reactor packing material employed in heterogeneous catalysis requires high porosity but simultaneously a certain robustness which has not been thoroughly investigated for powder-based 3D printing technologies before. With a calcination temperature of only 600 °C, sufficient consolidation by sintering does not occur as it would be the case for conventional Binder Jetting procedures so that the post-processing step of ambient slurry infiltration after debinding binds the particles after calcination at relatively low temperatures and significantly stabilizes the alumina framework while keeping the surface area and open porosity at catalytically relevant values of up to 223 m2/g and 80%, respectively. Uniaxial compression tests, density measurements and N2 physisorption elucidated the chemical composition, size accuracy, shrinkage behavior, side crushing strength, density, porosity and specific surface area of the green body as well as post-processed parts. Additionally, μCT scans offered a method to analyze the 3D printed character of the alumina carrier structure, effect of post-processing and an alternative way to assess part shrinkage next to size measurement.