Fabrication of self-supporting structures made of washcoat materials (γ-Al2O3-CeO2) by ceramic stereolithography: Towards digital manufacturing of enhanced catalytic converters

Abstract Despite increasing interest in the use of alternative fuel, conventional diesel or gasoline powered vehicles still dominate road transportation; removal of their emitted pollutants is a challenge to sustainable transportation. The automotive industry has employed catalytic converters (CCs) to effectively modify or eliminate toxic pollutants emitted by combustion engines. The efficiency of a CC greatly depends on its geometry and is hindered by limitations in fabrication techniques. To go beyond these limits and further enhance the performance of CCs, one can use state-of-the-art ceramic stereolithography (CSL) technology, which enables fabrication of complex-shaped structures. In this work, a novel photocurable ceramic resin made of γ - Al 2 O 3 and CeO 2 (the commonly used washcoat materials in CCs) is shaped into the honeycomb and twisted honeycomb structures using CSL. Measurements reveal that upon the addition of CeO 2 to the plain γ - Al 2 O 3 resin, the penetration depth of light is significantly decreased from 408.06  μ m to 75.19  μ m . This research also focuses on the balance between having a high surface area and achieving good physical stability in the printed structures. Accordingly, the appropriately debinded structures are sintered at two different temperatures: 900  ° C and 1100  ° C . It is found that the structure sintered at 900  ° C has a higher surface area, and thus, it is a better candidate for catalytic applications. Furthermore, investigation of the stabilizing effect of CeO 2 on printed γ - Al 2 O 3 finds that CeO 2 is effective in stabilizing the printed γ - Al 2 O 3 at1100  ° C but not 900  ° C. Targeting the realization of green and sustainable transportation, the applied CSL technique in this study enables flexible control in the design and fabrication of self-supporting structures that are expected to open promising ways for the optimization of CCs.