Preparation Of Pd/la_0.5Pb_0.5MnO₃by Rotating Packed Bed And Designing Of Three-phasemagnetic Stabilized Fluidized Bed

Diphenyl carbonate (Diphenyl carbonate, DPC) is an important engineering plastics intermediates, mainly used for the synthesis of general-purpose engineering plastics polycarbonate (polycarbonate, PC) synthesis. For the synthesis of DPC with oxidative carbonylation, more focus is on the study of catalysts and reaction conditions, less study on the reactor.The magnetically stabilized bed is a special kind of a fluidized bed, where the magnetic particles will show field orientation under the action of an applied magnetic, to form the stable bed. It has the operation advantage similar as fluidized bed and also doesn’t need to worry about solid particles away from the bed.Magnetically stabilized bed reactor is extremely beneficial for synthesis DPC system with heterogeneous oxidative carbonylation. Heterogeneous catalyst usually used in the synthesis of DPC is the palladium load powder particles, the use of a magnetically stabilized fluidized bed reactor can effectively suppress the loss of the precious metal palladium; In addition, the synthesis reaction of DPC is an exothermic reaction, using magnetically stabilized bed reactor can enhance the mass transfer and heat transfer of the reaction process.In this subject, the magnetically stabilized bed is used in synthesis engineering applications of DPC with oxidative carbonylation. Firstly magnetically stabilized bed is used in the cold model experiment of DPC synthesis. Solid catalyst used in magnetically stabilized bed of must have good magnetic properties and efficient catalytic activity in the hot mold test or the cold test.The perovskite composite the oxidation catalyst Pd/La0.5Pb0.5MnO3and perovskite composite oxide catalyst Pd/La0.5Pb0.5Mn(1-x)CuxO3with different percentage of Cu content is prepared with herein gravity under different process conditions. The catalyst’s structure and physical properties is tested binding with with characterization of XRD, BET and VSM.The effects of calcination temperature, overweight force beds speed and different proportions of Cu the carrier B site doping modification for catalytic activity and magnetic properties of the the perovskite compound the oxidation catalyst Pd/La0.5Pb0.5MnO3and perovskite composite oxide catalyst Pd/La0.5Pb0.5Mn(i-X)CuxO3is studied in order to determine the process conditions. According to the results of process conditions, filter out the solid catalys and engage in the design of the magnetically stabilized bed. Finally, the following results can be concluded:(1) When the calcination temperature is700℃, the catalytic activity of Pd/La0.5Pb0.5MnO3is best, yield of DPC is11.3%; when the calcination temperature is850°C, specific saturation magnetization of the catalyst is the biggest, Ms=25.54emu·g-1; The temperature should not be less than750℃when carrier meets the requirement of the magnetically stabilized bed.(2) For the high gravity bed speed, with its rotation speed up to1200r/min, the catalytic activity of Pd/La0.5Pb0.5MnO3is best, the catalytic activity of Pd/Lao.sPbo.sMnO3is10.2%; with it up to1000r/min, the catalyst’s specific saturation magnetization Ms up to max, that is,20.95emu·g-1. And for meeting the requirement of particles in MSB, the rotation speed should be between800to1400r/min..(3) For La0.5Pb0.5MnO3carrier, when it is doped with a low content of Cu, both of the catalytic activity and the saturation magnetization of the catalyst have been enhanced, while they are declining as the doping ratio to further improve the magnetic properties with the active., When the doping ratio x=0.2, DPC yield of11.6%; x=0.1, its saturation magnetization up to13.90emu·g-1(4) Under the condition of the catalyst’s saturation magnetization less than10emu· g-1, the catalyst with good catalytic activity and magnetic properties are selected for deciding three proper process conditions.(5) The main specifications of the magnetically stabilized bed reactor:sedimentation segment diameter of100mm, a height of300mm, fluidizing section of an inner diameter of50mm, an outer diameter of60mm, a height of600mm; magnetic field generating means of the electromagnetic induction coil, the magnetic field intensity in the range from0to380Oe is continuously adjustable, and the magnetic field is substantially uniform; the coil is cooled by the way of oil cooling coil-water-cooled oil.