The performance of supported catalysts is significantly affected by the dispersion degree of the active components on the support.In this study,citric acid(CA)was used as a modifier to prepare Al_(2)O_(3)supported Mn-...The performance of supported catalysts is significantly affected by the dispersion degree of the active components on the support.In this study,citric acid(CA)was used as a modifier to prepare Al_(2)O_(3)supported Mn-Ce oxides(Mn-Ce/CA-Al_(2)O_(3))by the impregnation-calcination method.The characterization results showed that adding citric acid enhanced the dispersion of Mn-Ce oxides on the support,rendering Mn-Ce/CA-Al_(2)O_(3)with a larger specific surface area and abundant surface hydroxyl groups,thereby providing more reaction sites for catalytic ozonation.The Mn-Ce/CA-Al_(2)O_(3)exhibited excellent catalytic ozonation performance in degrading Reactive Black 5(RB5)dye.It achieved nearly complete decolorization of RB5 within 60 min,with a COD removal efficiency of 60%,which was superior to the sole ozonation(30%).Furthermore,the Mn-Ce/CA-Al_(2)O_(3)system demonstrated significant degradation of RB5 over a wide pH range of 3e11.Based on the XPS and EPR analysis results,a preliminary mechanism of catalytic ozonation over the Mn-Ce/CA-Al_(2)O_(3)was proposed.The redox cycle of Mn^(3+)/Mn^(4+)and Ce^(3+)/Ce^(4+)effectively accelerated the electron transfer process,thus promoting the generation of reactive oxygen species(ROS)and improving the degradation of RB5.Meanwhile,the Mn-Ce/CA-Al_(2)O_(3)exhibited superior catalytic stability and effective treatment capabilities for real dye wastewater.展开更多
In this study,a series of Mn-Ce/Al_(2)O_(3) catalysts was prepared by different methods of depositionprecipitation(MnCeAl-DP),impregnation(MnCeAl-IM) and citric acid(MnCeAl-CA),and the distinct effect of preparation m...In this study,a series of Mn-Ce/Al_(2)O_(3) catalysts was prepared by different methods of depositionprecipitation(MnCeAl-DP),impregnation(MnCeAl-IM) and citric acid(MnCeAl-CA),and the distinct effect of preparation methods on NO_(x) removal performance at low temperature was explored.Results show that MnCeAl-DP exhibits not only the best activity but also the highest resistance against SO_(2)/H_(2)O.With the assistance of comprehensive characterizations from scanning electron microscopy(SEM),Brunauer-Emmett-Teller(BET),X-ray diffraction(XRD),H_(2)-temperature programmed reduction(H_(2)-TPR),NH_(3)-te mperature programmed deso rption(NH_(3)-TPD),and X-ray photoelectron spectroscopy(XPS),it is revealed that the MnCeAl-DP sample owns admired features of large surface area and pore volume,enriched Mn^(4+) and chemisorbed oxygen species originating from enhanced interaction between MnO_x and CeO_(2),as well as improved adsorption capacity to NH_(3) and NO.All these factors contribute to activity enhancement.Further in-situ DRIFTS studies reveal that the improvement of NH_(3)-SCR performance over MnCeAI-DP is related to the formation of abundant nitrate species,which is beneficial to the "NH_(4)NO_(3)" reaction pathway and thus enhances low-temperature activity.展开更多
采用自制线管式介质阻挡放电反应器,针对非热等离子体协同Mn-Ce/La/γ-Al_2O_3催化剂对低浓度甲苯的去除开展研究。研究中制备了Mn/γ-Al_2O_3、Mn-Ce/γ-Al_2O_3、Mn-La/γ-Al_2O_3催化剂,从甲苯去除率、产物O_3生成、CO_x选择性及其...采用自制线管式介质阻挡放电反应器,针对非热等离子体协同Mn-Ce/La/γ-Al_2O_3催化剂对低浓度甲苯的去除开展研究。研究中制备了Mn/γ-Al_2O_3、Mn-Ce/γ-Al_2O_3、Mn-La/γ-Al_2O_3催化剂,从甲苯去除率、产物O_3生成、CO_x选择性及其他副产物生成情况考察比较了空管放电、协同催化剂放电时催化降解甲苯性能,并对催化剂进行了BET、SEM、H2-TPR和ICP-OES表征研究。结果表明:稀土助剂的加入有助于提高甲苯去除率及降低程度,且La催化性能优于Ce.,当外加电压22 k V、气量6 L·min-1、甲苯初始浓度600 mg·m-3时,Mn-La/γ-Al_2O_3催化剂对甲苯去除率达到72.74%。H2-TPR结果表明,稀土助剂的加入提高了催化剂低温活性及储氧能力,添加La的效果优于Ce。催化剂有助于抑制副产物O_3生成,提高CO_2和COx选择性。展开更多
基金supported by the National Key Research and Development Program(2023YFC3207003)the National Natural Science Foundation of China(51878448).
文摘The performance of supported catalysts is significantly affected by the dispersion degree of the active components on the support.In this study,citric acid(CA)was used as a modifier to prepare Al_(2)O_(3)supported Mn-Ce oxides(Mn-Ce/CA-Al_(2)O_(3))by the impregnation-calcination method.The characterization results showed that adding citric acid enhanced the dispersion of Mn-Ce oxides on the support,rendering Mn-Ce/CA-Al_(2)O_(3)with a larger specific surface area and abundant surface hydroxyl groups,thereby providing more reaction sites for catalytic ozonation.The Mn-Ce/CA-Al_(2)O_(3)exhibited excellent catalytic ozonation performance in degrading Reactive Black 5(RB5)dye.It achieved nearly complete decolorization of RB5 within 60 min,with a COD removal efficiency of 60%,which was superior to the sole ozonation(30%).Furthermore,the Mn-Ce/CA-Al_(2)O_(3)system demonstrated significant degradation of RB5 over a wide pH range of 3e11.Based on the XPS and EPR analysis results,a preliminary mechanism of catalytic ozonation over the Mn-Ce/CA-Al_(2)O_(3)was proposed.The redox cycle of Mn^(3+)/Mn^(4+)and Ce^(3+)/Ce^(4+)effectively accelerated the electron transfer process,thus promoting the generation of reactive oxygen species(ROS)and improving the degradation of RB5.Meanwhile,the Mn-Ce/CA-Al_(2)O_(3)exhibited superior catalytic stability and effective treatment capabilities for real dye wastewater.
基金Project supported by the National Natural Science Foundation of China (22272077,22276097,21976081)Major Scientific and Technological Project of Bingtuan (2018AA002)。
文摘In this study,a series of Mn-Ce/Al_(2)O_(3) catalysts was prepared by different methods of depositionprecipitation(MnCeAl-DP),impregnation(MnCeAl-IM) and citric acid(MnCeAl-CA),and the distinct effect of preparation methods on NO_(x) removal performance at low temperature was explored.Results show that MnCeAl-DP exhibits not only the best activity but also the highest resistance against SO_(2)/H_(2)O.With the assistance of comprehensive characterizations from scanning electron microscopy(SEM),Brunauer-Emmett-Teller(BET),X-ray diffraction(XRD),H_(2)-temperature programmed reduction(H_(2)-TPR),NH_(3)-te mperature programmed deso rption(NH_(3)-TPD),and X-ray photoelectron spectroscopy(XPS),it is revealed that the MnCeAl-DP sample owns admired features of large surface area and pore volume,enriched Mn^(4+) and chemisorbed oxygen species originating from enhanced interaction between MnO_x and CeO_(2),as well as improved adsorption capacity to NH_(3) and NO.All these factors contribute to activity enhancement.Further in-situ DRIFTS studies reveal that the improvement of NH_(3)-SCR performance over MnCeAI-DP is related to the formation of abundant nitrate species,which is beneficial to the "NH_(4)NO_(3)" reaction pathway and thus enhances low-temperature activity.
文摘采用自制线管式介质阻挡放电反应器,针对非热等离子体协同Mn-Ce/La/γ-Al_2O_3催化剂对低浓度甲苯的去除开展研究。研究中制备了Mn/γ-Al_2O_3、Mn-Ce/γ-Al_2O_3、Mn-La/γ-Al_2O_3催化剂,从甲苯去除率、产物O_3生成、CO_x选择性及其他副产物生成情况考察比较了空管放电、协同催化剂放电时催化降解甲苯性能,并对催化剂进行了BET、SEM、H2-TPR和ICP-OES表征研究。结果表明:稀土助剂的加入有助于提高甲苯去除率及降低程度,且La催化性能优于Ce.,当外加电压22 k V、气量6 L·min-1、甲苯初始浓度600 mg·m-3时,Mn-La/γ-Al_2O_3催化剂对甲苯去除率达到72.74%。H2-TPR结果表明,稀土助剂的加入提高了催化剂低温活性及储氧能力,添加La的效果优于Ce。催化剂有助于抑制副产物O_3生成,提高CO_2和COx选择性。
