On developing ferrisilicate catalysts supported on silicon carbide (SiC) foam catalysts for continuous catalytic wet peroxide oxidation (CWPO) reactions

Fe supported catalysts show great promise for enabling practical environmental catalysis, exemplified by the catalytic wet peroxide oxidation (CWPO) process. In order to mitigate the Fe leaching issue, a strategy of assembling zeolitic coatings with intraframework Fe (ferrisilicate) on SiC foams was developed, showing a good stability in CWPO and a low Fe leaching of 2.0 mg l⁻¹. Direct hydrothermal synthesis of ferrisilicate/SiC foam composites was systematically studied, showing that their characteristics depend on the growth time, pH value and iron concentration of the growth solution. Selected ferrisilicate/SiC foam composite was evaluated using the continuous CWPO of phenolic aqueous solution at 60 °C. The open-cell size of SiC foam was varied between 800 and 2,000 μm and showed insignificant effect on the hydrodynamics of the flow process at 1 ml min ⁻¹, but the process efficiency in terms of phenol and total-organic-carbon (TOC) conversions was favored by a high surface-to-volume ratio (i.e. small open-cell sizes). Ferrisilicate/SiC foam catalysts (average open-cell size = 800 μm) showed good stability in the model system with the stable conversions of phenol (97%), H₂O₂ (84%) and TOC (37%) over 24 h time-on-stream.