A process capable of simultaneously oxidizing NO, SO2, and Hg^0 was proposed, using a nigh-voltage and short-duration positive pulsed corona discharge. By focusing on NO, SO2, and Hg^0 oxidation efficiencies, the infl...A process capable of simultaneously oxidizing NO, SO2, and Hg^0 was proposed, using a nigh-voltage and short-duration positive pulsed corona discharge. By focusing on NO, SO2, and Hg^0 oxidation efficiencies, the influences of pulse peak voltage, pulse frequency, initial concentration, electrode number, residence time and water vapor addition were investigated. The results indicate that NO, SO2 and Hg^0 oxidation efficiencies depend primarily on the radicals （OH, HO2, O） and the active species （O3, H2O2, etc.） produced by the pulsed corona discharge. The NO, SO2 and Hg^0 oxidation efficiencies could be improved as pulse peak voltage, pulse frequency, electrode number and residence time increased, but they were reduced with increasing initial concentrations. By adding water vapor, the SO2 oxidation efficiency was improved remarkably, while the NO oxidation efficiency decreased slightly. In our experiments, the simultaneous NO, SO2, and Hg^0 oxidation efficiencies reached to 40%, 98%, and 55% with the initial concentrations 479 mg/m^3, 1040 mg/m^3, and 15.0 μg/m^3, respectively.展开更多
Catalytic oxidation of toluene over noble metal catalysts is a representative reaction for elimination of volatile organic compounds(VOCs).However,to fully understand the activation of molecular oxygen and the role of...Catalytic oxidation of toluene over noble metal catalysts is a representative reaction for elimination of volatile organic compounds(VOCs).However,to fully understand the activation of molecular oxygen and the role of active oxygen species generated in this reaction is still a challenging target.Herein,MgO nanosheets and single-atom Pt loaded MgO(Pt SA/MgO)nanosheets were synthesized and used as catalysts in toluene oxidation.The activation process of molecular oxygen and oxidation performance on the two catalysts were contrastively investigated.The Pt SA/MgO exhibited significantly enhanced catalytic activity compared to MgO.The oxygen vacancies can be easily generated on the Pt SA/MgO surface,which facilitate the activation of molecular oxygen and the formation of active oxygen species.Based on the experimental data and theoretical calculations,an active oxygen species promoted oxidation mechanism for toluene was proposed.In the presence of H2O,the molecular oxygen is more favorable to be dissociated to generate•OH on the oxygen vacancies of the Pt SA/MgO surface,which is the dominant active oxygen species.We anticipate that this work may shed light on further investigation of t10.1007/s12274-020-2765-1he oxidation mechanism of toluene and other VOCs over noble metal catalysts.展开更多
CuFe-SSZ-13 catalyst showed excellent performance in the selective catalytic reduction of NO_x with NH_3(NH_3-SCR) for diesel engine exhaust purification. To investigate the effect of preparation methods on NH_3-SCR p...CuFe-SSZ-13 catalyst showed excellent performance in the selective catalytic reduction of NO_x with NH_3(NH_3-SCR) for diesel engine exhaust purification. To investigate the effect of preparation methods on NH_3-SCR performance, Fe was loaded into one-pot synthesized Cu-SSZ-13 catalysts through solid-state ion-exchange(SSIE), homogeneous deposition precipitation(HDP) and liquid ion-exchange(IE), respectively. Three CuFe-SSZ-13 catalysts showed similar SO_2 resistance, which was better than that of Cu-SSZ-13. The improvement was attributed to the protection of Fe species. Hydrothermal stability of three CuFe-SSZ-13 catalysts was significantly different, which was attributed to the state of active species caused by different preparation methods. Compared with the other two catalysts, more active species existed inside the zeolite pores of CuFe-SSZ-13 SSIE. During hydrothermal aging, the aggregation of these active species in the pores caused the collapse of catalyst structure, ultimately leading to the deactivation of CuFe-SSZ-13 SSIE. In contrast, Fe species was dispersed better on the surface over CuFe-SSZ-13 IE, enhancing the hydrothermal stability of catalysts. Consequently, Fe loading effectively improved the resistance of SO_2 and H_2O over Cu-SSZ-13. For CuFe-SSZ-13, large amounts of active species located inside the zeolite pores are not beneficial for the hydrothermal stability.展开更多
基金supported by the Science and Technology Research of Department of Education of China (No. 0305,03087)
文摘A process capable of simultaneously oxidizing NO, SO2, and Hg^0 was proposed, using a nigh-voltage and short-duration positive pulsed corona discharge. By focusing on NO, SO2, and Hg^0 oxidation efficiencies, the influences of pulse peak voltage, pulse frequency, initial concentration, electrode number, residence time and water vapor addition were investigated. The results indicate that NO, SO2 and Hg^0 oxidation efficiencies depend primarily on the radicals （OH, HO2, O） and the active species （O3, H2O2, etc.） produced by the pulsed corona discharge. The NO, SO2 and Hg^0 oxidation efficiencies could be improved as pulse peak voltage, pulse frequency, electrode number and residence time increased, but they were reduced with increasing initial concentrations. By adding water vapor, the SO2 oxidation efficiency was improved remarkably, while the NO oxidation efficiency decreased slightly. In our experiments, the simultaneous NO, SO2, and Hg^0 oxidation efficiencies reached to 40%, 98%, and 55% with the initial concentrations 479 mg/m^3, 1040 mg/m^3, and 15.0 μg/m^3, respectively.
基金This work was financially supported by National Natural Science Foundation of China (Nos. 51808037, 21601136 and 21876010)the Science & Technology Development Fund of Tianjin Education Commission for Higher Education (No. 2018KJ126)the Fundamental Research Funds for the Central Universities (No. FRF-TP-16-060A1).
文摘Catalytic oxidation of toluene over noble metal catalysts is a representative reaction for elimination of volatile organic compounds(VOCs).However,to fully understand the activation of molecular oxygen and the role of active oxygen species generated in this reaction is still a challenging target.Herein,MgO nanosheets and single-atom Pt loaded MgO(Pt SA/MgO)nanosheets were synthesized and used as catalysts in toluene oxidation.The activation process of molecular oxygen and oxidation performance on the two catalysts were contrastively investigated.The Pt SA/MgO exhibited significantly enhanced catalytic activity compared to MgO.The oxygen vacancies can be easily generated on the Pt SA/MgO surface,which facilitate the activation of molecular oxygen and the formation of active oxygen species.Based on the experimental data and theoretical calculations,an active oxygen species promoted oxidation mechanism for toluene was proposed.In the presence of H2O,the molecular oxygen is more favorable to be dissociated to generate•OH on the oxygen vacancies of the Pt SA/MgO surface,which is the dominant active oxygen species.We anticipate that this work may shed light on further investigation of t10.1007/s12274-020-2765-1he oxidation mechanism of toluene and other VOCs over noble metal catalysts.
基金supported by the National Natural Science Foundation of China(No.51508231)
文摘CuFe-SSZ-13 catalyst showed excellent performance in the selective catalytic reduction of NO_x with NH_3(NH_3-SCR) for diesel engine exhaust purification. To investigate the effect of preparation methods on NH_3-SCR performance, Fe was loaded into one-pot synthesized Cu-SSZ-13 catalysts through solid-state ion-exchange(SSIE), homogeneous deposition precipitation(HDP) and liquid ion-exchange(IE), respectively. Three CuFe-SSZ-13 catalysts showed similar SO_2 resistance, which was better than that of Cu-SSZ-13. The improvement was attributed to the protection of Fe species. Hydrothermal stability of three CuFe-SSZ-13 catalysts was significantly different, which was attributed to the state of active species caused by different preparation methods. Compared with the other two catalysts, more active species existed inside the zeolite pores of CuFe-SSZ-13 SSIE. During hydrothermal aging, the aggregation of these active species in the pores caused the collapse of catalyst structure, ultimately leading to the deactivation of CuFe-SSZ-13 SSIE. In contrast, Fe species was dispersed better on the surface over CuFe-SSZ-13 IE, enhancing the hydrothermal stability of catalysts. Consequently, Fe loading effectively improved the resistance of SO_2 and H_2O over Cu-SSZ-13. For CuFe-SSZ-13, large amounts of active species located inside the zeolite pores are not beneficial for the hydrothermal stability.
