The Development of Complex Ceramic Monoliths using Additive Manufacturing Techniques for Methane Oxidation Applications

Davidson, Callum Paul (2025) The Development of Complex Ceramic Monoliths using Additive Manufacturing Techniques for Methane Oxidation Applications. Doctoral thesis (PhD), Manchester Metropolitan University.

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Abstract

The research presented examines the use of 3D printing for ceramic catalytic substrates. The main aim was to try and reduce the amount of methane emissions being emitted from a dual fuel exhaust stream by utilising a more effective catalytic converter and using 3D printing to achieve this. The motivation for this thesis was initiated by G-Volution Ltd, who funded this project and owns a patent for a unique dual fuel system which can be fitted to any diesel engine, but which currently emits more methane than is allowed by EU regulations. To begin, CAD software was used to design monolithic substrates with a more complex internal channel structure than those seen in conventional, extruded monoliths. These substrates were manufactured using two different AM techniques: robocasting and digital light processing. A unique, in-house, photosensitive ceramic resin was synthesised to print intricate ceramic substrates. This required intensive research to produce, as this is not something which was available in literature or on the commercial market at the time of printing. This was the most time-consuming part of the thesis due to the difficulty of the synthesis process and the number of components required and is considered as the greatest achievement of this project. Characterisation techniques for the manufacturing material and final substrates included XRF, XRD, SEM, and TGA. A total of 16 substrates were manufactured using the named AM techniques with designs based on the stacking of individual, layered fibres rotated along different axes. To compare these designs catalytically, each substrate was washcoated in the same catalyst and tested for the complete oxidation of methane using a purpose-built testing rig. A commercial 400 CPSI monolith was subject to the same wash coating procedure for comparison. All the 3D printed designs tested outperformed the commercial 400 CPSI monolith at every temperature. The best 3D designs tested showed three times improved methane conversion at a temperature of 425 °C. The results explaining the designing, manufacturing and characterisation of these substrates, along with the catalytic testing results, will follow.