Low‐temperature selective catalytic reduction(SCR)of NO with NH3 was tested over Ho‐doped Mn–Ce/TiO2 catalysts prepared by the impregnation method.The obtained catalysts with different Ho doping ratios were charact...Low‐temperature selective catalytic reduction(SCR)of NO with NH3 was tested over Ho‐doped Mn–Ce/TiO2 catalysts prepared by the impregnation method.The obtained catalysts with different Ho doping ratios were characterized by Brunauer‐Emmett‐Teller(BET),X‐ray diffraction(XRD),temperature‐programmed reduction(H2‐TPR),temperature‐programmed desorption of NH3(NH3‐TPD),X‐ray photoelectron spectroscopy(XPS),and scanning electron microscopy(SEM).The catalytic activities were tested on a fixed bed.Their results indicated that the proper doping amount of Ho could effectively improve the low‐temperature denitrification performance and the SO2 resistance of Mn–Ce/TiO2 catalyst.The catalyst with Ho/Ti of 0.1 presented excellent catalytic activity,with a conversion of more than 90%in the temperature window of 140–220°C.The characterization results showed that the improved SCR activity of the Mn–Ce/TiO2 catalyst caused by Ho doping was due to the increase of the specific surface area,higher concentration of chemisorbed oxygen,higher surface Mn4+/Mn3+ratio,and higher acidity.The SO2 resistance test showed that the deactivating influence of SO2 on the catalyst was irreversible.The XRD and XPS results showed that the main reason for the catalyst deactivation was sulfates that had formed on the catalyst surface and that Ho doping could inhibit the sulfation to some extent.展开更多
F-V2 O5-WO3/Ti02 catalysts were prepared by the impregnation method.As the content of F ions increased from 0.00 to 0.35 wt.%,the NO conversion of F-V2 O5-WO3/TiO2 catalysts initially increased and then decreased.The ...F-V2 O5-WO3/Ti02 catalysts were prepared by the impregnation method.As the content of F ions increased from 0.00 to 0.35 wt.%,the NO conversion of F-V2 O5-WO3/TiO2 catalysts initially increased and then decreased.The 0.2 F-V2 O5-WO3/TiO2 catalyst(0.2 wt.%F ion)exhibited the best denitration(De-NOx)performance,with more than 95%NO conversion in the temperature range 160-360℃,and 99.0%N2 selectivity between 110 and 280℃.The addition of an appropriate amount of F ions eroded the surface morphology of the catalyst and reduced its grain size,thus enhancing the NO conversion at low temperature as well as the sulfur and water resistance of the V2 O5-WO3/Ti02 catalyst.After selective catalytic reduction(SCR)reaction in a gas flow containing SO2 and H2 O,the number of NH3 adsorption sites,active component content,specific surface area and pore volume decreased to different degrees.Ammonium sulfate species deposited on the catalyst surface,which blocked part of the active sites and reduced the NO conversion performance of the catalyst.On-line thermal regeneration could not completely recover the catalyst activity,although it prolonged the cumulative life of the catalyst.In addition,a mechanism for the effects of S02 and H2 O on catalyst NO conversion was proposed.展开更多
An Fe/TiO2catalyst with uniform mesopores was synthesized using Pluronic F127as a structuredirecting agent.This catalyst was used for selective catalytic reduction of NO with NH3.The catalytic activity and resistance ...An Fe/TiO2catalyst with uniform mesopores was synthesized using Pluronic F127as a structuredirecting agent.This catalyst was used for selective catalytic reduction of NO with NH3.The catalytic activity and resistance to H2O and SO2of Fe/TiO2prepared by a template method were better than those of catalysts synthesized using impregnation and coprecipitation.The samples were characterized using N2‐physisorption,transmission electron microscopy,ultraviolet‐visibl spectroscopy,X‐ray photoelectron spectroscopy,and in situ diffuse reflectance infrared Fouriertransform spectroscopy.The results showed that Pluronic F127acted as a structural and chemical promoter;it not only promoted the formation of a uniform mesoporous structure,leading to a higher surface area,but also improved dispersion of the active phase.In addition,the larger number of Lewis acidic sites,indicated by the presence of coordinated NH3species(1188cm-1)and the N–H stretching modes of coordinated NH3(3242and3388cm-1),were beneficial to mid‐temperature selective catalytic reduction reactions.展开更多
We reported data on thermal preference, thermal tolerance and the thermal dependence of digestive performance for two Phrynocephalus lizards （P. frontalis and P. versicolor）, and compared data among lizards so far s...We reported data on thermal preference, thermal tolerance and the thermal dependence of digestive performance for two Phrynocephalus lizards （P. frontalis and P. versicolor）, and compared data among lizards so far studied worldwide. Mean values for selected body temperature （Tsel） and critical thermal maximum （CTMax） were greater in P versicolor, whereas mean values for critical thermal minimum （CTMin） did not differ between the two species. The two lizards differed in food intake, but not in food passage time, apparent digestive coefficient （ADC） and assimilation efficiency （AE）, across the experimental tem- peratures. Four general conclusions can be drawn from published data. Firstly, thermal preference and thermal tolerance differ among lizards differing in distribution, temporal activity pattern and habitat use. Lizards in thermally more variable regions are better able to tolerate low and high temperatures. Diurnal lizards generally select higher body temperatures than nocturnal lizards, and lizards using habitats with direct sun exposure generally selected higher body temperatures and are better able to tolerate high temperatures. Secondly, CTMax is positively correlated with Tsel. Lizards more likely exposed to extremely high temperatures while active select higher body temperatures than those using shaded habitats. Thirdly, the effects of body temperature on food intake, food passage time, ADC and AE differ among lizards, but it seems to be common among lizards that ADC and AE are less thermally sensitive than food intake and food passage time. Lastly, ADC is dependent on the type of food ingested, with insectivorous lizards digesting food more efficiently than herbivorous lizards展开更多
Selective catalytic reduction technology using NH3 as a reducing agent（NH3-SCR） is an effective control method to remove nitrogen oxides. TiO2-supported vanadium oxide catalysts with different levels of Ce and Sb mo...Selective catalytic reduction technology using NH3 as a reducing agent（NH3-SCR） is an effective control method to remove nitrogen oxides. TiO2-supported vanadium oxide catalysts with different levels of Ce and Sb modification were prepared by an impregnation method and were characterized by X-ray diffractometer（XRD）, Brunauer-Emmett-Teller（BET）, Transmission electron microscopy（TEM）, Fourier transform infrared spectroscopy（FT-IR）, UV-Vis diffuse reflectance spectroscopy（UV-Vis DRS）, Raman and Hydrogen temperature-programmed reduction（H2-TPR）. The catalytic activities of V5 CexS by/TiO2 catalysts for denitration were investigated in a fixed bed flow microreactor. The results showed that cerium, vanadium and antimony oxide as the active components were well dispersed on TiO2, and the catalysts exhibited a large number of d-d electronic transitions, which were helpful to strengthen SCR reactivity. The V5 CexS by/TiO2 catalysts exhibited a good low temperature NH3-SCR catalytic activity. In the temperature range of 210 to 400℃, the V5 CexS by/TiO2 catalysts gave NO conversion rates above 90%. For the best V5Ce35Sb2/TiO2 catalyst, at a reaction temperature of 210℃, the NO conversion rate had already reached 90%. The catalysts had different catalytic activity with different Ce loadings. With the increase of Ce loading, the NO conversion rate also increased.展开更多
We maintained adult many-lined sun skinks(Mabuya multifasciata; 12 females and 12 males) collected from Hainan(southern China) in September 2006 in two outdoor enclosures to examine the effect of feeding condition on ...We maintained adult many-lined sun skinks(Mabuya multifasciata; 12 females and 12 males) collected from Hainan(southern China) in September 2006 in two outdoor enclosures to examine the effect of feeding condition on selected body temperature(Tsel).Skinks shifted their thermal preferences when fasted.Temporal variation in Tsel was not found within each sex feeding condition combination,and neither in fed nor in fasted skinks did the mean values for Tsel differ between sexes.Body temperatures selected by fed skinks fell within the range from 30.2 to 33.9 C,and those selected by fasted skinks within the range from 25.1 to 31.8 C.Body temperatures(31.8 0.3 C) selected by fed skinks were on average 4.0 C higher than those(27.8 0.4 C) selected by fasted skinks.Fasted skinks had no difficulty in attaining higher body temperatures,but they voluntarily shift their thermal preferences downwards to save energy.This finding suggests an adaptive mechanism adopted by many-lined sun skinks to enhance their fitness during the periods when food availability is low.展开更多
文摘Low‐temperature selective catalytic reduction(SCR)of NO with NH3 was tested over Ho‐doped Mn–Ce/TiO2 catalysts prepared by the impregnation method.The obtained catalysts with different Ho doping ratios were characterized by Brunauer‐Emmett‐Teller(BET),X‐ray diffraction(XRD),temperature‐programmed reduction(H2‐TPR),temperature‐programmed desorption of NH3(NH3‐TPD),X‐ray photoelectron spectroscopy(XPS),and scanning electron microscopy(SEM).The catalytic activities were tested on a fixed bed.Their results indicated that the proper doping amount of Ho could effectively improve the low‐temperature denitrification performance and the SO2 resistance of Mn–Ce/TiO2 catalyst.The catalyst with Ho/Ti of 0.1 presented excellent catalytic activity,with a conversion of more than 90%in the temperature window of 140–220°C.The characterization results showed that the improved SCR activity of the Mn–Ce/TiO2 catalyst caused by Ho doping was due to the increase of the specific surface area,higher concentration of chemisorbed oxygen,higher surface Mn4+/Mn3+ratio,and higher acidity.The SO2 resistance test showed that the deactivating influence of SO2 on the catalyst was irreversible.The XRD and XPS results showed that the main reason for the catalyst deactivation was sulfates that had formed on the catalyst surface and that Ho doping could inhibit the sulfation to some extent.
基金supported by the National Key Research and Development Program of China(No.2017YFC0210303)the Key Research and Development Program of Hebei province of China(No.19273706D)+2 种基金the Beijing Millions of Talents Project(No.2018A36)the National Natural Science Foundation of China(No.21607009)the Youth Core Plan of Beijing Academy of Science and Technology(No.YC201806)
文摘F-V2 O5-WO3/Ti02 catalysts were prepared by the impregnation method.As the content of F ions increased from 0.00 to 0.35 wt.%,the NO conversion of F-V2 O5-WO3/TiO2 catalysts initially increased and then decreased.The 0.2 F-V2 O5-WO3/TiO2 catalyst(0.2 wt.%F ion)exhibited the best denitration(De-NOx)performance,with more than 95%NO conversion in the temperature range 160-360℃,and 99.0%N2 selectivity between 110 and 280℃.The addition of an appropriate amount of F ions eroded the surface morphology of the catalyst and reduced its grain size,thus enhancing the NO conversion at low temperature as well as the sulfur and water resistance of the V2 O5-WO3/Ti02 catalyst.After selective catalytic reduction(SCR)reaction in a gas flow containing SO2 and H2 O,the number of NH3 adsorption sites,active component content,specific surface area and pore volume decreased to different degrees.Ammonium sulfate species deposited on the catalyst surface,which blocked part of the active sites and reduced the NO conversion performance of the catalyst.On-line thermal regeneration could not completely recover the catalyst activity,although it prolonged the cumulative life of the catalyst.In addition,a mechanism for the effects of S02 and H2 O on catalyst NO conversion was proposed.
基金supported by the Strategic Priority Research Program of the Chinese Academy of Sciences(XDA07030300)~~
文摘An Fe/TiO2catalyst with uniform mesopores was synthesized using Pluronic F127as a structuredirecting agent.This catalyst was used for selective catalytic reduction of NO with NH3.The catalytic activity and resistance to H2O and SO2of Fe/TiO2prepared by a template method were better than those of catalysts synthesized using impregnation and coprecipitation.The samples were characterized using N2‐physisorption,transmission electron microscopy,ultraviolet‐visibl spectroscopy,X‐ray photoelectron spectroscopy,and in situ diffuse reflectance infrared Fouriertransform spectroscopy.The results showed that Pluronic F127acted as a structural and chemical promoter;it not only promoted the formation of a uniform mesoporous structure,leading to a higher surface area,but also improved dispersion of the active phase.In addition,the larger number of Lewis acidic sites,indicated by the presence of coordinated NH3species(1188cm-1)and the N–H stretching modes of coordinated NH3(3242and3388cm-1),were beneficial to mid‐temperature selective catalytic reduction reactions.
文摘We reported data on thermal preference, thermal tolerance and the thermal dependence of digestive performance for two Phrynocephalus lizards （P. frontalis and P. versicolor）, and compared data among lizards so far studied worldwide. Mean values for selected body temperature （Tsel） and critical thermal maximum （CTMax） were greater in P versicolor, whereas mean values for critical thermal minimum （CTMin） did not differ between the two species. The two lizards differed in food intake, but not in food passage time, apparent digestive coefficient （ADC） and assimilation efficiency （AE）, across the experimental tem- peratures. Four general conclusions can be drawn from published data. Firstly, thermal preference and thermal tolerance differ among lizards differing in distribution, temporal activity pattern and habitat use. Lizards in thermally more variable regions are better able to tolerate low and high temperatures. Diurnal lizards generally select higher body temperatures than nocturnal lizards, and lizards using habitats with direct sun exposure generally selected higher body temperatures and are better able to tolerate high temperatures. Secondly, CTMax is positively correlated with Tsel. Lizards more likely exposed to extremely high temperatures while active select higher body temperatures than those using shaded habitats. Thirdly, the effects of body temperature on food intake, food passage time, ADC and AE differ among lizards, but it seems to be common among lizards that ADC and AE are less thermally sensitive than food intake and food passage time. Lastly, ADC is dependent on the type of food ingested, with insectivorous lizards digesting food more efficiently than herbivorous lizards
基金supported by the Natural Science Foundation of China (Nos. 21376261, 21173270)the Beijing Natural Science Foundation (2142027)+1 种基金Doctor select Foundation (No. 20130007110007)the National Hi-Tech Research and Development Program (863) of China (No. 2013AA065302)
文摘Selective catalytic reduction technology using NH3 as a reducing agent（NH3-SCR） is an effective control method to remove nitrogen oxides. TiO2-supported vanadium oxide catalysts with different levels of Ce and Sb modification were prepared by an impregnation method and were characterized by X-ray diffractometer（XRD）, Brunauer-Emmett-Teller（BET）, Transmission electron microscopy（TEM）, Fourier transform infrared spectroscopy（FT-IR）, UV-Vis diffuse reflectance spectroscopy（UV-Vis DRS）, Raman and Hydrogen temperature-programmed reduction（H2-TPR）. The catalytic activities of V5 CexS by/TiO2 catalysts for denitration were investigated in a fixed bed flow microreactor. The results showed that cerium, vanadium and antimony oxide as the active components were well dispersed on TiO2, and the catalysts exhibited a large number of d-d electronic transitions, which were helpful to strengthen SCR reactivity. The V5 CexS by/TiO2 catalysts exhibited a good low temperature NH3-SCR catalytic activity. In the temperature range of 210 to 400℃, the V5 CexS by/TiO2 catalysts gave NO conversion rates above 90%. For the best V5Ce35Sb2/TiO2 catalyst, at a reaction temperature of 210℃, the NO conversion rate had already reached 90%. The catalysts had different catalytic activity with different Ce loadings. With the increase of Ce loading, the NO conversion rate also increased.
基金supported by the National Natural Science Foundation of China (Project No. 30670281) Chinese Ministry of Education (Project No. 20070319006) and Nanjing Normal University
文摘We maintained adult many-lined sun skinks(Mabuya multifasciata; 12 females and 12 males) collected from Hainan(southern China) in September 2006 in two outdoor enclosures to examine the effect of feeding condition on selected body temperature(Tsel).Skinks shifted their thermal preferences when fasted.Temporal variation in Tsel was not found within each sex feeding condition combination,and neither in fed nor in fasted skinks did the mean values for Tsel differ between sexes.Body temperatures selected by fed skinks fell within the range from 30.2 to 33.9 C,and those selected by fasted skinks within the range from 25.1 to 31.8 C.Body temperatures(31.8 0.3 C) selected by fed skinks were on average 4.0 C higher than those(27.8 0.4 C) selected by fasted skinks.Fasted skinks had no difficulty in attaining higher body temperatures,but they voluntarily shift their thermal preferences downwards to save energy.This finding suggests an adaptive mechanism adopted by many-lined sun skinks to enhance their fitness during the periods when food availability is low.
