The Preparation For New Multimetal Catalysts And Research On Ozone Catalytic Oxidation Technology

With the continuous development of China's petrochemical industry,the pollution problem has become increasingly serious,and the country has also increasingly attached importance to environmental protection issues.However,the treatment of toxic,harmful and difficult-to-degrade organic pollutants is very limited.Traditional sewage treatment processes do not degrade such contaminants well.As a result,emerging sewage treatment technologies have developed rapidly.In this paper,?-Al2O3 and ceramsite were used as carriers,and transition metals and rare elements were used as active components.Catalysts were prepared by excess impregnation and applied in wastewater treatment.The heterogeneous organic ozone catalytic oxidation technology was used to remove refractory organics in water.In the experiment,the refractory methylene blue was selected as the sewage model.The optimum preparation conditions of catalyst were investigated by changing the type,content and immersion time of the loaded metal.Selecting Mn,Cu,Ni,Fe,Cr,Zn and other transition metals and rare earth elements as the supporting metal to design 10 different catalyst preparation schemes,it is concluded that the three most active catalysts are:Mn-Cu-Fe-Ce/?-Al2O3,Mn-Cu-Ni-Ce/?-Al2O3 and Mn-Cu-Zn-Ce/?-Al2O3.On this basis,the content of loaded metal was changed.The optimum concentration ratio of the three catalysts was 1:1:2:0.5,and the optimal immersion time was 12 h.After knowing the best loading metal type and its content,change the roasting time and roasting temperature to find the best roasting process.The optimum preparation process of catalyst Mn-Cu-Fe-Ce/?-Al2O3 was calcined at 450? for 3.5 h.The best roasting process of Mn-Cu-Ni-Ce/?-Al2O3 and Mn-Cu-Zn-Ce/?-Al2O3 was performed at 450 ? for 4 h.The inductively coupled plasma emission spectroscopy and electron scanning microscopy were used to analyze the actual loading content and microscopic morphology of the catalyst.The analysis results are in agreement with the experimental results.After repeated use of the catalyst,its activity did not decrease.At the same time,the mechanism of catalytic oxidation of ozone was preliminary investigated.Replacement of ceramic particles as a carrier for the preparation of the catalyst,its activity is lower than the ?-Al2O3 carrier.According to the previous experimental conditions,the Computational Fluid Dynamics in the ozone catalytic oxidation reactor was performed.The bubble column with the same experimental conditions was selected,with a height of 180 cm and a diameter of 50 mm.Methylene blue wastewater and ozone were passed downstream from the bottom into the column.The inflow rate was 4 L/h and the ozone dosage was 150 mg/L.Using FLUETN software,the gas-liquid two-phase values in the bubble column were simulated and the gas-liquid distribution at different heights in the column was investigated.The simulation results show that the gas-liquid mixing is best in the middle of the tower,while the gas-liquid mixing is not good in the gas-liquid inlet and transition sections.Analysis of the fluid in the reactor provides theoretical guidance for future industrial application of the process.