Ceramic hollow fibre catalytic converters for automotive emissions control

Abstract

The development of ceramic hollow fibre catalytic converters for the control of automotive emission has been presented in this thesis. Attempts have been made to understand the different factors such as the fabrication of the substrate, the effects of the washcoat packing, the variations of the catalytic reactions at different catalyst formulations, and the evaluation of the pressure drop in the new substrate structure, since these factors may cause a real hindrance in the development of a new ceramic hollow fibre catalytic converter. An asymmetric ceramic hollow fibre substrate was fabricated through the extrusion process, assisted by a phase-inversion. The produced substrate resulted in a hollow fibre with an array of microchannels with almost double the hydraulic diameter of the commercial 400 cells per inch square (CPSI) honeycomb monolith, which lead to less pressure drop in the system. The hollow fibre substrate can offer a tremendous increase in the geometric surface area (GSA), which is beneficial for catalyst layer deposition. With the new structure, a new washcoating technique has been proposed. A loosely packed washcoat in the microchannel has been identified as the best configuration. After the successful conversion of CO at a low light-off temperature and low precious metal loading, two perovskite catalysts have been synthesised, and their catalytic activity in the hollow fibre catalytic converter has been assessed. This result indeed highlights the advantage of the new proposed structure for catalytic converters in order to control tailpipe emissions.