Advances in Catalysis Design from Micro to Macroscale for Heterogeneous Catalytic Ozonation: A Critical Review

Catalytic ozonation has gained increasing attention as an advanced oxidation process (AOP) capable of overcoming some limitations of conventional ozonation in water treatment, particularly incomplete pollutant mineralization and the formation of undesirable by-products. This review provides a critical assessment of recent advances in heterogeneous catalytic ozonation, covering developments from microscale powdered catalysts to macrostructured supported systems. While research has predominantly focused on suspended microscale catalysts, a growing number of studies have investigated macrostructured materials due to their potential advantages for catalyst handling, recovery, and implementation in continuous-flow processes. The influence of catalyst composition, including metal oxides, carbon-based materials, and composite systems, on catalytic performance and stability is discussed. Although still an emerging research area, macrostructured catalysts have demonstrated promising characteristics that may facilitate catalyst recovery and continuous operation, making them attractive candidates for large-scale catalytic ozonation applications. The analysis also reveals important research gaps, particularly regarding long-term stability under continuous operation, scale-up studies, catalyst deactivation mechanisms, and the evaluation of real wastewater matrices. Future research should focus on developing robust, scalable catalytic systems that combine high activity, durability, and ease of recovery while meeting the requirements of sustainable and circular economy principles for advanced water treatment applications.