Synthesis of monodispers-porous oxidation catalysts carrying active centers in the form of metal nanoparticles and their usage in benzyl alcohol oxidation

In the scope of the thesis, monodisperse-porous oxidation catalysts carrying active centers in the form of metal nanoparticles were developed in order to be used in benzyl alcohol oxidation. Firstly, monodisperse-porous CeO2 microbeads which will be used as support material were synthesized by sol-gel templating method. Pd nanoparticles with oxidation potential were immobilized onto the derivatized CeO2 microbeads. In the following step, the usability of Pd nanoparticle immobilized CeO2 microbeads in the benzyl alcohol oxidation as a catalyst was examined. Surface morphology and size distribution of the catalyst were analyzed by scanning electron microscopy (SEM). Surface morphology and size distribution of the Pd nanoparticles were analyzed by transmission electron microscope (TEM). The pore size distribution and specific surface areas were determined by using the nitrogen adsorption/desorption method (BET). Crystal structure was investigated with X-ray diffraction method (XRD) and finally the surface atomic compositions were investigated by energy dispersive X-ray spectroscopy (EDX). In the benzyl alcohol oxidation experiments, the effect of porous structure of support material, the immobilization path of Pd nanoparticles, Pd nanoparticle content of catalyst, catalyst amount, initial benzyl alcohol concentration and oxidizing agent (TBHP) concentration on the catalytic performance were investigated. As a result, the catalyst (Pd@PEI@CeO2 (%10 Pd) having the highest catalytic activity was synthesized by using CeO2 microbeads calcined at 550 oC and derivatized with PEI and includes % 10 paladium by weight. The highest benzyl alcohol conversion and benzaldehyde selectivity were obtained with Pd@PEI@CeO2 (%10 Pd) catalyst as % 84.78 and % 91,91, respectively. Reusability of the Pd@PEI@CeO2 (%10 Pd) catalyst was tested and benzyl alcohol conversion and benzaldehyde selectivity at the end of the 5 cycles were found as % 83,24 and % 78,23, respectively. These results show that the developed catalyst performs benzyl alcohol oxidation with high conversion and high selectivity and is reusable.