Study On Direct Synthesis Of Hydrogen Peroxide From Hydrogen And Oxygen In Membrane Reactor

Direct formation of hydrogen peroxide from hydrogen and oxygen has been actively investigated in catalysis for its atom economy, simple process and cleanly product. The catalysis system of the reaction was studied in this paper and the reaction was also investigated in the membrane reactor.A series of Pd/alumina catalysts which were used for the synthesis of hydrogen peroxide from hydrogen and oxygen directly were prepared by incipient wetness impregnation technique. The effects of Pd loading, Pd resource, the pretreatment on carrier by halogenation and reaction medium were investigated. The catalytic active state of Pd on the surface of catalyst was investigated according to the XPS characterization. The results show that the conversion of hydrogen is increased with the solubility of hydrogen in the liquid media. Both methanol and acetone are perfect reaction medium. The carrier pretreated by halogenation increases the selectivity of catalyst enormously. The Pd resources containing Cl- perform well and the best Pd resource is PdCl₂. When the Pd loading is 1.88% the value of TOF and the concentration of hydrogen peroxide are both perfect. The active state of Pd is Pd0 because Pd only can exist as the form of Pd0 in the reaction system.Pd based membrane catalysts were prepared with Plating Pd, Ag separately and simultaneously process on the single channelα-Al₂O₃ tube. Then they were characterized by SEM and penetration experiment. The results show that the both two kinds of membrane have good hydrogen penetrability and the membrane plating simultaneously has better penetrability because of its lower thickness. The pinholes still exist on the surface of membrane for the rough surface of support and plating process.The effect of plating process and H2 penetrate pressure to the reaction was studied. Based on the results, another layer of Pd was plated on the alloy membrane to ameliorate the membrane catalyst. The results show that the activity of membrane catalyst was enhanced when another layer of Pd was plated. The concentration of hydrogen peroxide was enhanced when the hydrogen penetrate pressure increased. When the pressure was 30KPa the concentration reached 0.98g/L that exceeded the value reported highly.