Ferrite Catalyst Preparation via Epoxide Sol-Gel Method

The patent employs a sol-gel method to create a porous catalyst structure with high surface area. The gel formation process creates an interconnected porous network that maintains catalyst activity while enabling simple bulk preparation. The porous structure allows reactant access to active sites throughout the catalyst matrix, resolving the contradiction between bulk form and catalytic activity.

The patent changes the preparation parameters from conventional coprecipitation to sol-gel chemistry, controlling pH, temperature, and aging conditions to form a gel structure. This parameter change transforms the catalyst morphology from dense bulk to porous structure, maintaining ease of manufacture while dramatically improving catalytic activity through increased surface area and accessible active sites.

The porous gel structure formed by the sol-gel method creates a self-supporting catalyst matrix that retains shape during drying. This structure eliminates the need for extensive filtration and washing steps required in coprecipitation methods, as the gel can be directly dried and calcined. The interconnected pores allow efficient solvent removal through evaporation rather than filtration, significantly reducing processing time.

The sol-gel process performs preliminary consolidation of the catalyst precursors into a gel structure before drying. This preliminary action creates a rigid network that prevents particle disintegration during solvent removal, eliminating the need for subsequent filtration and washing operations. The gel structure is formed in advance, allowing direct transition to drying and calcination steps.

The patent carefully controls the burning temperature and atmosphere parameters to prevent α-Fe2O3 formation. By limiting the maximum burning temperature and controlling oxygen exposure during calcination, the catalyst maintains a stable spinel phase structure with high catalytic reactivity. The parameter control ensures structural stability while avoiding the formation of less active iron oxide phases.

The catalyst forms a composite spinel structure where multiple metal oxides are integrated in a cooperative arrangement. This composite structure provides both structural stability and high catalytic activity, as the different metal components work synergistically. The spinel phase composition resists transformation to α-Fe2O3 while maintaining active sites for oxidation reactions, resolving the contradiction between stability and reactivity.