Synthesis Of Magnetic Catalyst For Oxidative Carbonylation Of Phenol To Diphenyl Carbonate And Its Cold-model Experiment In Magnetically Stabilized Bed

Heterogeneous magnetic palladium catalysts supported on composite oxides demonstrate theoretical and practical values in oxidative carbonylation of phenol to diphenyl carbonate（DPC） for the green chemical engineering. This catalytic system is easy separated and the function of reoxidation additives, as well as the possible application in the magnetically stability bed（MSB） reactors which could strengthen heat and mass transfer because of the distinct magnetic properties.The performance of magnetic spinel manganese ferrite supporter was studied for direct synthesis of DPC. It was determined that the catalytic activity was related to the surface activity and the mobile oxygen species of the supporter. Though different metal doping and changing the calcination temperature to improve the catalytic activity of the obtained MnFe₂O₄ supporter, which from the co-precipitation method. Because of the small grain size and high surface activity produced by the easy formed surface defects, the DPC yield of the catalyst which the supporter was prepared by co-precipitation method reached 7.48% with the specific surface area up to 163 m2/g, and the specific saturation magnetization（Ms） was 25.6 emu/g. The copper or lead doping enhanced the surface activity and mobile oxygen content, then enhanced the DPC yield to 11.53% with the Ms was 20.3 emu/g when the PbO mass ratio was 10%.The Fluent simulation software and cold-model experiment were employed to research the distribution and bed pressure drop of the magnetic Pd/10%PbO-MnFe₂O₄ particles in the MSB reactor. The results showed that the magnetic strength（H） played a key role on the magnetic particles distribution and bed pressure drop. When the gas velocity was 0.25 m/s, H was 40 kA/m, after 2 seconds the solid distribution could reach stable and the interface of the bed was clear. Because the solid centralized in the bottom of the bed, the pressure drop was improved. With the help of laser emitter and receiver, we obtained the relation between laser intensity and the solid content on one section of the MSB reactor in the cold-model experiment. The experiment result showed that the magnetic particles were centralized to the field region as the H was improving then enhanced the bed pressure drop. The simulation and cold-model experiment results match well, so we sure that the prepared magnetic Pd/10%PbOMnFe₂O₄ particles could applied on the designed MSB reactor. At the same time, we can choose the appropriate magnetic strength according to the Ms of the magnetic catalyst to control its distribution in the MSB reactor, then improve the mass and heat transfer efficiency of the gas-liquid-solid fluidized bed.