چكيده به لاتين
In the present study, a new three-component and four-component magnetic nanocomposite were synthesized as follows: Zirconium ferrite as a magnetic core coated with silica and modified with tetrakis (4-carboxyphenyl) porphyrin (TCPP) and manganese tetrakis (4-carboxyphenyl) porphyrin (TCPP acetate) successfully prepared. As part of this project, to compare the bond stability between silica and porphyrin, nanocomposites consisting of porphyrin attached to silica on the magnetic core by an amino linker (ZrFe2O4@SiO2-NH-TCPP) and nanocomposite that porphyrin-free linker attached to the silica (ZrFe2O4 @ SiO2 -TCPP, ZrFe2O4 @ SiO2-TNPP and ZrFe2O4@ SiO2-TAPP) were synthesized. As part of this project, to compare the bond stability between silica and porphyrin, nanocomposites were synthesized by porphyrin attached to silica on the magnetic core by an amino linker (ZrFe2O4@SiO2-NH-TCPP) and nanocomposite that has a porphyrin-free linker attached to the core silica (ZrFe2O4 @ SiO2 -TCPP, ZrFe2O4 @ SiO2-TNPP and ZrFe2O4@ SiO2-TAPP) synthesis. In order to investigate the catalytic activity, ZrFe2O4@SiO2-MnTCPP and ZrFe2O4@SiO2-NH-MnTNPP nanocomposites were synthesized. The as-prepared nanocomposites were studied and identified by FT-IR, XRD, XPS, SEM, EDX, DRS, VSM, BET and TGA. Then they were evaluated as catalysts in the oxidation of cyclohexane to obtain valuable products of oxidation cyclohexanone and cyclohexanol which characterized by GC-Mass.The results indicated that the fabricated nanocomposites not only have a good catalytic activity in this type of reaction, but also can be easily separated from the reaction medium by applying an external magnetic field. Among these synthesized nanocomposite, ZrFe2O4@SiO2-NH-TCPP nanocomposite has been introduced as heterogeneous catalysts for selective oxidation of cyclohexane to cyclohexanol with 100% selectivity and 36% conversion. In addition, photocatalytic activities of prepared samples were investigated for removal of methyl orange under visible LED light irradiation. In the next step, new three- and four-component zirconium ferrite ZrFe2O4@ZrO2-TCPP, ZrFe2O4@ZrO2-NH-TCPP, ZrFe2O4@ZrO2-TNPP, ZrFe2O4@ZrO2-TAPP, ZrFe2O4@ZrO2-TNPP, ZrFe2O4@ZrO2-MnTCPP and ZrFe2O4@ZrO2-NH-MnTNPP nanocomposites were successfully synthesized with appropriate magnetic recovery. The synthesized nanocomposites were identified by FT-IR, SEM, TEM, EDX, XRD, VSM, TGA and BET techniques. The catalytic activity of the synthesized nanocomposites was studied for the oxidation of cyclohexane and compared with the results of pure zirconium ferrite and ZrFe2O4@ZrO2. The results indicated that the modification of these nanocomposites with porphyrin and metalloporphyrin resulted in a good catalytic activity. The obtained results showed that the ZrFe2O4@ZrO2-NH-MnTCPP magnetic nanocomposite showed better catalytic activities than other nanocomposites, with the highest efficiency (98.3%) in cyclohexane oxidation ith selectivity of 100% cyclohexanone and conversion rate of 52.14% which was evaluated by GC-Mass. Significant advantages of this catalyst include remarkable activity, easily separation from the reaction medium by external magnetic field, adequate heat and reaction stability, reusability up to 5 times, and selective oxidation of cyclohexane to cyclohexanol with appropriate productivity.
