[Experimental research of purification NO-containing gas by aqueous oxidation with UV/H2O2].

The influence of some experimental factors on removal efficiency of nitric oxide (NO) under the condition of liquid-phase oxidation with UV/H2O2, such as H2O2 concentration, solution temperature, initial pH, NO concentration, illumination condition, O2 content and gas flow rate, were investigated by employing orthogonal experiments and single factor experiments. The results showed that NO could be efficiently removed by the aqueous oxidation technology with UV/H2O2 system, and the highest NO removal rate was about 80%. Moreover, H2O2 concentration, temperature and initial pH had varying degree effects on purifying NO-containing gas, whereas NO removal rate were more affected by H2O2 concentration and temperature. The single factor experimental results showed that high NO removal rate could be obtained when H2O2 concentration was 0.2 mol/L and the initial pH was 6-7. H2O2 concentration and initial pH should be maintained at an appropriate level or the production of *OH could be restricted, which would result in lower NO removal rate. The optimum operation temperature was 40 degrees C, which is lower than common operating temperature (50 degrees) for the wet scrubber. Enlarging the illumination strength and O2 content could improve the NO removal rate. Furthermore, the NO removal rate was also controlled by the area and coefficient of gas-liquid mass transfer.

[Research on SCR denitrification of MnOx/Al2O3 modified by CeO2 and its mechanism at low temperature].

The Al2O3,which has large specific surface area and is used as carrier,was prepared by sol-gel method in this study. Series catalysts of MnOx, CeO2 plus MnOx supported on Al2O3 by isometric impregnation method. The SCR denitrification experimental conditions were as follows: NH3 as reductive agent, certain gas velocity and suitable ratio of gas mixed was setup. Furthermore, the experiments of BET, XRD and SEM were also carried out respectively in order to obtain physicochemical properties of the prepared catalysts. The experimental results showed that the loading of active component and calcination temperature made a big difference to the catalysts' performance. With appropriate addition of CeO2, MnOx/Al2O3 exhibits better activity and stability. For MnOx/Al2O3, the catalytic activity on NO was greatly influenced by its loaded content, and 7% MnOx/Al2O3 showed superior catalytic activity among the MnOx/Al2O3. The addition of CeO2 could greatly improve the dispersibility of MnOx on the carrier and increase its catalytic activity. The 4% CeO2 addition was the optimum loaded mass precent. Forthermore, 550 degrees C is the best calcination temperature, as MnOx formed different crystalline phases with temperature, at the same time, the addition of CeO2 could affect MnOx crystalline phase. The catalytic mechanism of SCR on NO was also discussed.

[Reaction of NO with metal oxides and urea supported on activated carbons at low temperature].

The catalysts were prepared by activated carbon fiber (ACF) loaded different contents of NiO and NiO-CeO2, Urea was loaded on the prepared catalysts as reductant. The experiments of selective catalytic reductions (SCR) of NO were carried out from 30 to 120 degrees C. The experiments of SEM, BET and XRD of the samples were also carried out selectively to study the catalysts properties, respectively. The experimental results showed that the loaded mass fraction of NiO could greatly affect the catalytic activity of the catalysts. 10% NiO catalyst activity and activity stability were both higher than that of the others, and it could yield about 50% removal efficiency of NO at 90 degrees C. With the loaded mass increasing, the catalytic activity was obviously decreased. And furthermore, the catalyst of 5% NiO-5% CeO2/ACF had the best catalytic activities on SCR NO and stability among the prepared NiO-CeO2/ACF catalysts, and its NO removal efficiency was over 55% at 110 degrees C. When the loaded mass increased, the similar phenomenon was observed, which was due to the decreasing of specific surface area of the catalysts. The metal oxides, loaded on ACF, were the catalytic centers in this study. Moreover, 5% CeO2-5% NiO/ACF had the highest catalytic activity than 10% CeO2/ACF and 10% NiO/ ACF. Therefore, there should be synergistic effect between CeO2 and NiO. Finally, the catalytic mechanism of SCR on NO at low temperature was discussed.