SiOC and SiCN-based ceramic supports for catalysts and photocatalysts

Abstract

Nowadays, most industrial chemical products employ catalysts as an essential step to synthesize many commodities. Inspired by catalytic processes, the discovery of Honda-Fujishima, reported by analogy with natural photosynthesis, boosted the overall scientific interest in photocatalysis. This area aims for feasible energy generation and pollutants abatement, looking for beyond the efficiency under UV light, new perspectives towards visible light through novel composites. Suspended catalysts are commonly used due to simplicity, primarily to demonstrate concepts in lab-scale research. However, working with suspensions is not technologically feasible, and immobilizing on supports avoids the toxicity associated with free catalysts and facilitates further separation processes. Thus, immobilized catalysts on tailor-made porous support form heterojunctions and profiles as a more practical approach to tackling these challenges. In addition, involving just stable semiconductors within the system enables applying catalytic systems in harsh environments. The polymer-derived ceramic (PDCs) route has been studied in another technological frontier, addressing several technical issues over the past 50 years, allowing for coatings, foams, and fibers with controlled morphology and good thermal-oxidative resistance. Those features make PDCs promising supports for catalyst immobilization, particularly, SiOC and SiCN-based ceramics. This work provides an overview of PDCs and their interactions with catalysts. The manufacture approaches, catalyst type, component interactions, thermal treatment effects, catalytic activity under visible light, and other outcome properties are reviewed. Moreover, the research landscape and current challenges on catalysts supported by PDCs are discussed. Finally, the gaps regarding processing optimization and perspectives for PDC-based materials applied in catalyst-assisted systems are highlighted. • The application range of porous SiOC and SiCN supports in catalyst-assisted reactions under harsh environments are pointed up • An in-depth overview of SiOC and SiCN-based ceramics as supports and their effect in catalysis and photocatalysis is presented • Manufacturing approaches, type of catalyst, and intrinsic parameters of the as-obtained composites are discussed • Photocatalytic activity aiming to extend to the visible light adsorption is compared between the systems • The mechanism behind the performance is discussed thoroughly