Developing hierarchically structured catalysts on cellular foams for continuous flow catalysis

The development of modern chemical and environmental industry requires novel reactor concepts to enable the transfer of catalysts developed in laboratories into the industrial context. The applications of structured reactors/catalysts such as cellular foams are one of the most promising technologies that can facilitate this crucial step. Open-cell foams with stochastically interconnected cells and high porosities (>60%) can promote the low pressure drop during operation and improve the transport phenomena, overtaking the conventional fixed beds for continuous flow catalysis. In this PhD project, silicon carbide (SiC) cellular foams were investigated to evaluate the potential for developing heterogeneous catalysis using foam-based catalysts in continuous flow regime, due to the good compatibility with framework catalyst coatings and features of the cellular structure. The work was carried out by (i) studying morphological and structural features of SiC foams using X-ray computed tomography technique in relation to their implications for applications in chemical engineering; (ii) developing a microwave-assisted method based on the microwave absorbing feature of SiC for fast yet selective synthesis of zeolite (ZSM- 5) coatings on SiC foams; (iii) developing Fe-ZSM-5/SiC structured catalysts using a chemical vapour deposition method and subsequently studying their application as the foam bed reactor in the catalytic wet peroxide oxidation (CWPO) reaction (using phenol as the model compound); and (iv) developing intra-framework Fe-ZSM-5 catalyst on SiC foams (ferrisilicate/SiC) to address the Fe leaching issue from the Fe-ZSM-5/SiC catalyst. Satisfactory results were obtained through the systematic study of the SiC foam based catalysts, showing the potential of using SiC foams to develop structured catalysts for continuous flow environmental catalysis.