Sulfate adsorption is one of the factors that cause the poisoning of catalyst in the low-temperature NH_(3) selective catalytic reduction reaction(NH_(3)-SCR).In this paper,by controlling the co-adsorption time of SO_...Sulfate adsorption is one of the factors that cause the poisoning of catalyst in the low-temperature NH_(3) selective catalytic reduction reaction(NH_(3)-SCR).In this paper,by controlling the co-adsorption time of SO_(2) and O_(2) at 150℃,a range of sulfated MnCeOx catalysts with different contents of metal sulfate species were prepared to reveal the influence of metal sulfate species content on the catalytic performances and reaction mechanisms at low temperature.The catalytic activity below 250℃rapidly decreases with increasing metal sulfate species content.The results of characterizations shed light on the reduction of specific surface area,Mn^(4+)and Ce^(3+)content,and redox ability of MnCeOx owing to the formation of metal sulfate species.Further experiments reveal that metal sulfate species preferentially absorb on MnOx domains rather than on CeO_(2) domains,and the adsorbed metal sulfate species can suppress the Eley-Rideal and the Langmuir-Hinshelwood reaction mechanisms over the sulfated MnCeOx.All the above results are detrimental to the activity of sulfated MnCeOx in the low-temperature NH3-SCR reaction.展开更多
Persulfate(PS)-based oxidation technologies are attracting increasing attentions in water treatment due to their high efficiency and stability.In this study,a novel diatomite supported MnCeOx composite(MnCeOx/diatomit...Persulfate(PS)-based oxidation technologies are attracting increasing attentions in water treatment due to their high efficiency and stability.In this study,a novel diatomite supported MnCeOx composite(MnCeOx/diatomite) was prepared and characterized for activation of PS to degrade organic pollutants.Results indicated that diatomite not only dispersed MnCeOx and increased the specific surface area of catalyst,but also improved the low-valence metal site(Mn^2+and Ce^3+) and reactive oxygen species site(-OH) of MnCeOx,thus enhancing the activities of MnCeOx.MnCeOx/diatomite/PS showed high efficiency for multiple dyes and pharmaceutical pollutants.Constant rate(k) of MnCeOx/diatomite(kMnCeOx/diatomite) was three times higher than the sum of constant rate of MnCeOx(kMnCeOx)and constant rate of diatomite(kdiatomite).In addition,MnCeOx/diatomite showed wide pH application(5-9).Cl^- and NO3^2- had no effect while SO4^2- and humid acid had slightly negative effects on MnCeOx/diatomite/PS system.Moreover,MnCeOx/diatomite showed good reusability and stability.Mechanism analyses indicated that electron transfer of Mn and Ce attributed to the activation of PS and oxygen to produce free radicals.SO4·^-,·OH and O2·^-on the surface of catalyst were the main active free radicals to attack pollutants.展开更多
Indoor formaldehyde(HCHO)is an important air pollutant,while it is very difficult to reduce HCHO to low-level(e.g.<0.08 mg/m^(3)).Catalytic oxidation at ambient temperature has been increasingly recognized as one o...Indoor formaldehyde(HCHO)is an important air pollutant,while it is very difficult to reduce HCHO to low-level(e.g.<0.08 mg/m^(3)).Catalytic oxidation at ambient temperature has been increasingly recognized as one of the important methods to mitigate HCHO pollution due to its good effectiveness,stability,and recyclability.To further improve the activity of catalytic oxidation,this study develops the integrated MnCeO_(x)catalysts supported on palygorskite(Pal)and aluminium hydroxide(Al(OH)_(3)).Our results indicate that the synergistic interaction in MnCeO_(x)through the oxygen transfer mechanism from the oxygen reservoir CeO_(2)to MnOxsignificantly improves the activity.Pal,Al(OH)_(3),etc.were applied as the supports with a focus on their dispersion,microstructure,strength,and relative role.MnCeO_(x)can be anchored on the surface of Al(OH)_(3)with high dispersion.With the integrated catalyst,HCHO concentration decreases from 1.012 to 0.086 mg/m^(3)within 48 h.Higher oxidation activity of MnCeO_(x)powder may be ascribed to the amount of active components on the surface.The incorporation of ZSM-5 and activated carbon can improve the adsorption of HCHO,and all integrated catalysts exhibit stronger activities,with HCHO being degraded to the level lower than 0.08 mg/m^(3).Meantime,the samples exhibit good stability and strength(20.2 MPa)without obvious decrease over five consecutive stability experiments.展开更多
基金Project supported by the National Natural Science Foundation of China(21607019)the Scientific andTechnological Research Program of Chongqing Municipal Education Commission(KJQN202101242,KJQN202001227)+2 种基金the Science andTechnology Project of Wanzhou(wzstc-2019034)the Open Project Program of Key Laboratory of Water Environment Evolution andPollution Control in the Three Gorges Reservoir(WEPKL2019ZD-04)the Project Program of Chongqing Postgraduate Research andInnovation(CYS21489)。
文摘Sulfate adsorption is one of the factors that cause the poisoning of catalyst in the low-temperature NH_(3) selective catalytic reduction reaction(NH_(3)-SCR).In this paper,by controlling the co-adsorption time of SO_(2) and O_(2) at 150℃,a range of sulfated MnCeOx catalysts with different contents of metal sulfate species were prepared to reveal the influence of metal sulfate species content on the catalytic performances and reaction mechanisms at low temperature.The catalytic activity below 250℃rapidly decreases with increasing metal sulfate species content.The results of characterizations shed light on the reduction of specific surface area,Mn^(4+)and Ce^(3+)content,and redox ability of MnCeOx owing to the formation of metal sulfate species.Further experiments reveal that metal sulfate species preferentially absorb on MnOx domains rather than on CeO_(2) domains,and the adsorbed metal sulfate species can suppress the Eley-Rideal and the Langmuir-Hinshelwood reaction mechanisms over the sulfated MnCeOx.All the above results are detrimental to the activity of sulfated MnCeOx in the low-temperature NH3-SCR reaction.
基金supported by the National Water Pollution Control and Treatment Science and Technology Major Project (No.2018ZX07110003).
文摘Persulfate(PS)-based oxidation technologies are attracting increasing attentions in water treatment due to their high efficiency and stability.In this study,a novel diatomite supported MnCeOx composite(MnCeOx/diatomite) was prepared and characterized for activation of PS to degrade organic pollutants.Results indicated that diatomite not only dispersed MnCeOx and increased the specific surface area of catalyst,but also improved the low-valence metal site(Mn^2+and Ce^3+) and reactive oxygen species site(-OH) of MnCeOx,thus enhancing the activities of MnCeOx.MnCeOx/diatomite/PS showed high efficiency for multiple dyes and pharmaceutical pollutants.Constant rate(k) of MnCeOx/diatomite(kMnCeOx/diatomite) was three times higher than the sum of constant rate of MnCeOx(kMnCeOx)and constant rate of diatomite(kdiatomite).In addition,MnCeOx/diatomite showed wide pH application(5-9).Cl^- and NO3^2- had no effect while SO4^2- and humid acid had slightly negative effects on MnCeOx/diatomite/PS system.Moreover,MnCeOx/diatomite showed good reusability and stability.Mechanism analyses indicated that electron transfer of Mn and Ce attributed to the activation of PS and oxygen to produce free radicals.SO4·^-,·OH and O2·^-on the surface of catalyst were the main active free radicals to attack pollutants.
基金Project supported by the Natural Science Foundation of Jiangsu Province(BK20170954,BK20150890,BK20190786)the National Natural Science Foundation of China(21501097,51902166)。
文摘Indoor formaldehyde(HCHO)is an important air pollutant,while it is very difficult to reduce HCHO to low-level(e.g.<0.08 mg/m^(3)).Catalytic oxidation at ambient temperature has been increasingly recognized as one of the important methods to mitigate HCHO pollution due to its good effectiveness,stability,and recyclability.To further improve the activity of catalytic oxidation,this study develops the integrated MnCeO_(x)catalysts supported on palygorskite(Pal)and aluminium hydroxide(Al(OH)_(3)).Our results indicate that the synergistic interaction in MnCeO_(x)through the oxygen transfer mechanism from the oxygen reservoir CeO_(2)to MnOxsignificantly improves the activity.Pal,Al(OH)_(3),etc.were applied as the supports with a focus on their dispersion,microstructure,strength,and relative role.MnCeO_(x)can be anchored on the surface of Al(OH)_(3)with high dispersion.With the integrated catalyst,HCHO concentration decreases from 1.012 to 0.086 mg/m^(3)within 48 h.Higher oxidation activity of MnCeO_(x)powder may be ascribed to the amount of active components on the surface.The incorporation of ZSM-5 and activated carbon can improve the adsorption of HCHO,and all integrated catalysts exhibit stronger activities,with HCHO being degraded to the level lower than 0.08 mg/m^(3).Meantime,the samples exhibit good stability and strength(20.2 MPa)without obvious decrease over five consecutive stability experiments.
