Preparation Of Magnetic Catalyst For Oxidative Carbonyl Of Phenol To Diphenyl Carbonate And Its Flow Characteristics In The Magnetic Fluidized Bed

Diphenyl Carbonate(DPC) is an important raw material for producing general engineering polycarbonates. The main synthesis methods of DPC include phosgene method, transesterificaton and oxidative carbonylation of phenol. Oxidative carbonylation method which conforming to the green chemistry and the requirement of low carbon economy development mode has become the main direction of research and development at home and abroad as its advantages, such as avoiding using toxic phosgene, high utilization of atomic, non-toxic by-product H2 O.The direct synthesis of DPC with oxidative carbonylation includes homogeneous catalysis and heterogeneous catalysis. Homogeneous catalysis is gradually replaced by heterogeneous catalysis for its serious corrosion of equipment and difficulty of separation. The hot research spot at heterogeneous catalysis is focus on the choice of cocatalytic systems and the soild support. The heterogeneous catalytic reaction mostly was carried out in a batch reactor or fixed bed reactor. As these reactors have poor heat and mass transfer effect, high pressure-drops, the catalytic efficiency in these reactors were not satisfactory. The magnetically stabilized bed(MSB) reactor combining the advantages of the fixed bed and the fluidized bed can improve the efficiency of the catalytic reaction by improving the heat and mass transfer. In this work, MSB reactor was applied to the synthesis of DPC by oxidative carbonylation of phenol through studying the properties of MSB by numerical simulation and cold model experiments, design and preparation of magnetic catalysts.In the numerical simulation of MSB, the GAMBIT was applied to establish a two-dimensional model and import the model into the Fluent. The Eulerian model was used to simulate flow state in MSB under different operating conditions. In the simulation process, the solid La0.5Pb0.5MnO3 was regarded as quasi fluid, flow model was the standard k-ε model and the magnetic field was import by UDF model. Through the simulation result we find: in the MSB which set the gas as driving force, the pressure-drop of the bed was stable after the bed fully fluidized; the velocity of liquid has little impacted on distribution of solid phase as it’s much smaller than the velocity of gas; high opening rate is in favor of fluidization and it can reduce the total pressure-drop; enhance the magnetic field strength can stable solid phase particles.The strength of magnetic field of the MSB was measured in the cold model experiment. The measurement results show that the strength of magnetic field was very uneven and it related to the turns of the excitation coil. The intensity of the magnetic field can be controlled by current size. The pressure-drop under different Ug was measured and obtained the Umf by analysis the figure of Ug-ΔP. The Umf under different conditions was compared and it showed that the Umf increased as the intensity of magnetic field increase, UL increase or opening rate of distributing plate decrease. The average holdup of gas was increase by the Ug increase and it has a line relationship between them.In design and preparation of magnetic catalysts, the magnetic carrier La0.5Pb0.5MnO3 and MnFe2O4 was combined by the method of precipitation and a new composite carrier MnFe2O4-La0.5Pb0.5MnO3@Al2O3 was prepared. The redox properties and magnetic properties of the new carrier was measured by VSM and H2-TPR. The composite carrier with high content La0.5Pb0.5MnO3 has better redox performance. And increasing the content of MnFe2O4 can improve the magnetic properties of carrier. The saturation of 0.4MnFe2O4-0.4La0.5Pb0.5MnO3@0.2Al2O3 can reach 34.8 emu·g-1, when it loaded 0.5% Pd, the catalytic synthesis of DPC yield was 7.5%. It’s a suitable catalyst carrier for MSB.