Preparation and characterization of layered solids containing tin(IV) ions for the immobilization of metalloporphyrins and use in catalytic oxidation reaction

This study investigates metalloporphyrins immobilized on layered double and triple hydroxides (LDHs) as reusable catalysts for oxidation reactions. Two layered solids containing Zn²⁺/Sn⁴⁺ and Zn²⁺/Al³⁺/Sn⁴⁺ were synthesized by coprecipitation and characterized by SEM, XRD, and FTIR. Tin(IV) and iron(III) metalloporphyrins with the same porphyrin structure were immobilized on these supports in water at room temperature. The resulting MP-LDH materials showed loadings of approximately 1 × 10⁻⁶ mol of metalloporphyrin per gram of LDH. Their catalytic and photocatalytic performances were evaluated through the degradation of methylene blue and the oxidation of 1,5-dihydroxynaphthalene. Reaction time, temperature, catalyst mass, and catalyst reuse were varied to compare the efficiency of double and triple LDHs and the influence of the metal center in the metalloporphyrins.