| Currently, the emission of nitric oxide (NOx) in China is increasing day by day. Selective catalytic reduction (SCR) is a widely used technology to remove the NOx from stationary sources. Catalyst is the core of this reaction system, and its performence directly influence the denitration efficiency of SCR system. After a period of time of situ application, the catalyst would become deactivated. The deactivated catalyst could be regenerated by various kinds of physical and chemical method to eliminate the harmful substance and increase the active site. Because the thermal power unit installed capacity of China is increasing constantly and the SCR technology is being applied in those plants, so there will be much more deactivated catalyst in the future. Therefore, the study of catalyst regeneration is obiviously important. With the financial support of project of "Technology and equipment of coordinated control the multi pollutants for coal-fired power plants" from the National High Technology Research and Development of China (863Program)(No.2013AA065401), Natural Science Foundation of China (outstanding youth)(No.51125025), science and technology planning project of "Research and demonstration of completely product the SCR catalyst" in Zhejiang province, the microwave-ethanol assisted regeneration of catalyst was performed to evaluate effect of regenerated technology and operating parameters on the denitrated concentration of catalyst. The main results are shown as following:1. The effect of pore-enlarging agent and the concentration of pore-enlarging agent were studied. It was founded that ethanol had a larger impact on the pore structure of catalyst than other kinds of pore-enlarging agent. In addition, when the volume concentration of ethanol was20%, the catalyst can get the best pore-enlarging effect. The surface area of this catalyst can be enhanced to123.2%compare to the deactivated sample. And its denitration efficiency on320℃can be increased from39%to63%. After dipping with the activated substance, the V content of microwave assisted regenerated catalyst can be increased for62.2%, which was only46.7%for the traditional regenerated method; the denitration efficiency of microwave assisted regenerated catalyst on320℃can be enhanced from39%to90%, which was80%for the traditional regenerated method. SEM images show that after the microwave assisted regeneration, the catalyst was more porosity than deactivated sample and traditional regenerated sample. XRD test results show that there was no effect of microwave assisted regenerated method on the crystal structure of catalyst. The compressive strength results show that the microwave assisted method can enhance the strength of catalyst for78N/cm2than deactivated sample, and the traditional method can only enhance the strength for37.6N/cm2. Those consequents have provided a possibility for the industrialization of microwave assisted regenerated method.2. The effect of microwave parameters during the pore-enlarging process on the pore structure of catalyst was studied. So did the effect of pore-enlarging times on the pore parameters of catalyst. The research about microwave power during the pore-enlarging process show that higher microwave power can lead to higher surface area. The surface area of catalyst was enhanced for only10.5%when the power was110W, but it enhanced for24.6%when the power was700W. When the catalyst was operated for different times of pore-enlarging process, the surface area of catalyst was increased along with the pore-enlarging times. And4times of pore-enlarging can lead to the highest surface area, which was increased for36.4%than deactivated sample. The V content and denitrated efficiency of catalyst was also increased with pore-enlarging times. After5times of pore-enlarging process, the V content of catalyst was increased for47.1%, and the denitrated efficiency of catalyst on320℃was increased for23.6%. For the traditional regenareted catalyst, the denitration efficiency can only be increased for9.4%. With rising of the times of pore-enlarging process, the compressive strength of catalyst increased first and then decreased. After the catalyst was performed for3times for pore-enlarging process, its strength was enhanced for161.2N/cm2than deactivated sample.3. The effect on the denitrated efficiency of drying method after dipping with activated substance was studied. The results show that because of the fast drying characteristic of microwave, the activated substance was distributed uniformly in the catalyst. For the sample enlarged by20%concentration of ethanol, if it was dried by microwave, the denitrated efficiency on320℃was enhanced to90%, but the efficiency was only increased to83%if the sample was dried by circulation oven. For the sample washed by water, if it was dried by microwave, the denitrated efficiency on320℃was enhanced to84.6%, but the efficiency was only increased to80.4%if the sample was dried by circulation oven. In addition, the strength of catalyst can be enhanced when the microwave power of drying was increased. |
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