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A comparative study of formaldehyde and carbon monoxide complete oxidation on MnO_x-CeO_2 catalysts 被引量:12
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作者 刘雪松 鲁继青 +2 位作者 千坤 黄伟新 罗孟飞 《Journal of Rare Earths》 SCIE EI CAS CSCD 2009年第3期419-424,共6页
MnOx-CeO2 composite catalysts were prepared by a coprecipitation method and tested for formaldehyde (HCHO) and carbon monoxide (CO) oxidation. X-ray photon spectroscopy (XPS) results indicated that the average o... MnOx-CeO2 composite catalysts were prepared by a coprecipitation method and tested for formaldehyde (HCHO) and carbon monoxide (CO) oxidation. X-ray photon spectroscopy (XPS) results indicated that the average oxidation state of surface Mn species in CeMn composite catalyst was higher compared to the pure MnOx. The enhancement of reactivity for HCHO oxidation was due to the activation of the lattice oxygen species in MnOx by the addition of CeO2, which was confirmed by the H2 temperature programmed reduction (HE-TPR) results. The remarkable enhancement of reactivity for CO oxidation by the addition of CeO2 was due to the active oxygen species generated on the CeO2 surface which directly participated in the reaction. 展开更多
关键词 MnOx-CeO2 catalysts complete oxidation HCHO CO rare earths
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Complete oxidation of 1,4-dioxane over zeolite-13X-supported Fe catalysts in the presence of air 被引量:2
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作者 C.Ramakrishna R.Krishna +4 位作者 T.Gopi G.Swetha Bijendra Saini S.Chandra Shekar Anchal Srivastava 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2016年第2期240-249,共10页
Zeolite-13X-supported Fe(Fe/zeolite-13X) catalysts with various Fe contents were prepared by the wet impregnation method.The catalysts were characterized by N2 adsorption-desorption isotherms to estimate the Brunaue... Zeolite-13X-supported Fe(Fe/zeolite-13X) catalysts with various Fe contents were prepared by the wet impregnation method.The catalysts were characterized by N2 adsorption-desorption isotherms to estimate the Brunauer-Emmett-Teller surface areas and Barrett-Joyner-Hanlenda pore size distributions.X-ray diffraction,scanning electron microscopy,temperature-programmed reduction,and temperature-programmed desorption of NH3 were used to investigate the textural properties of the Fe/zeolite-13 X catalysts.Their catalytic activities were determined for the complete oxidation of1,4-dioxane using air as the oxidant in a fixed-bed flow reactor in the temperature range 100-400℃.The influences of various process parameters,such as reaction temperature,metal loading,and gas hourly space velocity(GHSV),on the dioxane removal efficiency by catalytic oxidation were investigated.The stability of the catalyst was tested at 400℃ by performing time-on-stream analysis for 50 h.The Fe/zeolite-13 X catalyst with 6 wt%Fe exhibited the best catalytic activity among the Fe/zeolite-13 X catalysts at 400℃ and a GHSV of 24000 h^(-1),with 97%dioxane conversion and95%selectivity for the formation of carbon oxides(CO and CO2).Trace amounts( 3%) of acetaldehyde,ethylene glycol monoformate,ethylene glycol diformate,1,4-dioxane-2-ol,1,4-dioxane-2-one,and 2-methoxy-1,3-dioxalane were also formed as degradation products.A plausible degradation mechanism is proposed based on the products identified by GC-MS analysis. 展开更多
关键词 IRON Zeolite-13X 1 4-Dioxane Catalytic degradation complete oxidation Degradation mechanism
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A Review on Complete Oxidation of Methane at Low Temperatures 被引量:2
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作者 ZhenhuaLi GarB.Hoflund 《Journal of Natural Gas Chemistry》 EI CAS CSCD 2003年第3期153-160,共8页
This paper reviews recent developments in complete oxidation of methane atlow temperatures over noble metal catalysts in the past 20 years. The Pd/Al_2O_3 catalyst system isfully discussed. The review mainly focuses o... This paper reviews recent developments in complete oxidation of methane atlow temperatures over noble metal catalysts in the past 20 years. The Pd/Al_2O_3 catalyst system isfully discussed. The review mainly focuses on the kinetic aspects of methane oxidation over thiscatalyst, and methane activation behavior over Pd and PdO phases (the form of PdO on the surface,transient behavior, the nature of the active sites, the influence of metal particle size and theirstructure sensitivities, and so on). Some Pd catalysts supported on other oxides besides the Al_2O_3support are briefly discussed. Possible routes of non-noble metal catalysts as substitutes for thePd catalyst are also proposed. 展开更多
关键词 METHANE complete oxidation REVIEW PD low temperature noble metal
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Steady-state kinetics and osillation phenomena for complete oxidation of benzene over Pt/Al_2O_3 catalyst
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作者 Yu Qiquan, Jin Yun and Shi FajunDepartment of Chemistry,Peking University,Beijing 100871,China. 《Journal of Environmental Sciences》 SCIE EI CAS CSCD 1990年第2期41-50,共10页
The steady-state kinetics for complete oxidation of benzene over has been investigated by the external recycling reactor. The kinetics equation was described by the L-H model of adsorption of benzene and oxygen with t... The steady-state kinetics for complete oxidation of benzene over has been investigated by the external recycling reactor. The kinetics equation was described by the L-H model of adsorption of benzene and oxygen with the inhibition of carbon dioxide. The parameters of the kinetics model were estimated by the method of orthogonal design. The heats of adsorption of benzene, oxygen and carbon dioxide were determined by the method of gas-adsorption chromatography. The details of oscillations of complete oxidation of benzene were investigated. 展开更多
关键词 steady-state kinetics complete oxidation BENZENE Pt/Al2O3.
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Regulation of mixed Ag valence state by non-thermal plasma for complete oxidation of formaldehyde 被引量:1
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作者 Kai Li Jian Ji +1 位作者 Yanling Gan Haibao Huang 《Chinese Chemical Letters》 SCIE CAS CSCD 2022年第1期434-437,共4页
Formaldehyde is an important air pollutant and its removal is essential to protect human health and meet environmental regulations.Ag-based catalyst has a considerable potential for HCHO oxidation in low temperature r... Formaldehyde is an important air pollutant and its removal is essential to protect human health and meet environmental regulations.Ag-based catalyst has a considerable potential for HCHO oxidation in low temperature range.The valence state of Ag is one of the key roles in formaldehyde catalytic oxidation.However,its effect on activity is still ambiguous.Non-thermal plasma and conventional calcination were employed to regulate Ag valence state in this study.Three Ag-Co/CeO_(2)catalysts with totally different distribution of Ag species were obtained.A special mixed Ag valence state,~50%Ag^(δ+)with a few Ag^(0)and Ag^(+),was achieved by plasma activation.It had the merits of both good activity and stability.A close relationship between Ag valence state and the activity for HCHO oxidation was established.The activity of different Ag species follows the order:Ag^(δ+)+Ag^(0)+Ag^(+)>Ag^(δ+)>Ag^(0)>Ag^(+). 展开更多
关键词 Ag valence Non-thermal plasma HCHO complete oxidation Ag-based catalyst
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Complete oxidation of methane on Co_(3)O_(4)-SnO_(2) catalysts 被引量:1
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作者 Xingfu TANG Jiming HAO Junhua LI 《Frontiers of Environmental Science & Engineering》 SCIE EI CSCD 2009年第3期265-270,共6页
Co_(3)O_(4)-SnO_(2)hybrid oxides were prepared by the coprecipitation method and were used to oxidate methane(CH4)in presence of oxygen.The Co_(3)O_(4)-SnO_(2)with a molar ratio of Co/(Co+Sn)at 0.75 exhibited the high... Co_(3)O_(4)-SnO_(2)hybrid oxides were prepared by the coprecipitation method and were used to oxidate methane(CH4)in presence of oxygen.The Co_(3)O_(4)-SnO_(2)with a molar ratio of Co/(Co+Sn)at 0.75 exhibited the highest catalytic activity among all the Co_(3)O_(4)-SnO_(2)hybrid oxides.Experimental results showed that the catalysts were considerably stable in the CH4 combustion reaction,and were verified by X-ray photoelectron spectra(XPS).It was found that Co_(3)O_(4)was the active species,and SnO_(2)acted as a support or a promoting component in the Co_(3)O_(4)-SnO_(2)hybrid oxides.The surface area was not a major factor that affected catalytic activity.The hydrogen temperatureprogrammed reduction(H_(2)-TPR)results demonstrated that the interaction between cobalt and tin oxides accelerated the mobility of oxygen species of Co_(3)O_(4)-SnO_(2),leading to higher catalytic activity. 展开更多
关键词 Co_(3)O_(4)-SnO_(2) complete oxidation methane(CH_(4))
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Catalytic activity and crystal structure modification of Pd/γ-Al_2O_3–TiO_2 catalysts with different Al_2O_3 contents
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作者 Chengwu Yang Qian Zhang +3 位作者 Jun Li Ruirui Gao Zhe Li Wei Huang 《Journal of Energy Chemistry》 SCIE EI CAS CSCD 2016年第3期375-380,共6页
Pd/γ-Al2O3–TiO2catalysts containing various compositions of titania and alumina were prepared by sol–gel and wet-impregnation methods in attempt to study the particle size, nature of phases, morphology and structur... Pd/γ-Al2O3–TiO2catalysts containing various compositions of titania and alumina were prepared by sol–gel and wet-impregnation methods in attempt to study the particle size, nature of phases, morphology and structure of the composite samples. The ethanol oxidation experiments, N2adsorption–desorption,FTIR, XRD and XPS were conducted, and the effects of Al2O3content on the surface area, phase transformation and structural properties of TiO2were investigated. The optimal value of ethanol conversion appeared on Pd/Al(0.05)–Ti and Pd/Al(0.90)–Ti catalysts irrespective of the ethanol oxidation temperature, and we call this as a double peaks phenomenon of catalytic activity. The XRD results reveal that the phase composition and crystallite size of the mixed oxides depend on Al2O3/TiO2ratio and calcination temperature. Al2O3can effectively prevent the agglomeration of TiO2and this can be ascribed to the formation of Al–O–Ti chemical bonds in Al2O3–TiO2crystals. Binding energy and Pd surface concentration of the catalysts were modified apparently, which may also lead to catalyst activity changes. 展开更多
关键词 Ethanol complete oxidation Al_2O_3/TiO_2 ratio Double peaks phenomenon Calcination temperature
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Research progress and prospects of complete ammonia oxidizing bacteria in wastewater treatment 被引量:2
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作者 Shaoping Luo Yi Peng +1 位作者 Ying Liu Yongzhen Peng 《Frontiers of Environmental Science & Engineering》 SCIE EI CSCD 2022年第9期151-160,共10页
Complete ammonia oxidizing bacteria,or comammox bacteria(CAOB),can oxidize ammonium to nitrate on its own.Its discovery revolutionized our understanding of biological nitrification,and its distribution in both natural... Complete ammonia oxidizing bacteria,or comammox bacteria(CAOB),can oxidize ammonium to nitrate on its own.Its discovery revolutionized our understanding of biological nitrification,and its distribution in both natural and artificial systems has enabled a reevaluation of the relative contribution of microorganisms to the nitrogen cycle.Its wide distribution,adaptation to oligotrophic medium,and diverse metabolic pathways,means extensive research on CAOB and its application in water treatment can be promoted.Furthermore,the energy-saving characteristics of high oxygen affinity and low sludge production may also become frontier directions for wastewater treatment.This paper provides an overview of the discovery and environmental distribution of CAOB,as well as the physiological characteristics of the microorganisms,such as nutrient medium,environmental factors,enzymes,and metabolism,focusing on future research and the application of CAOB in wastewater treatment.Further research should be carried out on the physiological characteristics of CAOB,to analyze its ecological niche and impact factors,and explore its application potential in wastewater treatment nitrogen cycle improvement. 展开更多
关键词 complete ammonia oxidizing(comammox) bacteria Nitrogen cycle Physiological characteristics Wastewater treatment
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Main environmental drivers of abundance,diversity and community structure of comammox Nitrospira in paddy soils 被引量:1
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作者 Fuyun GAO Yaying LI +2 位作者 Haoxin FAN Jiantao XUE Huaiying YAO 《Pedosphere》 SCIE CAS CSCD 2023年第5期808-818,共11页
The recently discovered complete ammonia oxidizers comammox Nitrospira contain clades A and B that can establish an independent one-step nitrification process;however,little is known about their environmental drivers ... The recently discovered complete ammonia oxidizers comammox Nitrospira contain clades A and B that can establish an independent one-step nitrification process;however,little is known about their environmental drivers or habitat distributions in agricultural soils.Previous studies on comammox Nitrospira in paddy soils have mainly focused on small-scale samples,and there is a lack of multisite research on comammox Nitrospira in paddy soils.In this study,we conducted a survey of 36 paddy soils to understand the community structure,abundance,and diversity of comammox Nitrospira and the degree to which they are affected by environmental factors at a large scale.Comammox Nitrospira were found to be widely distributed among the paddy soils.The abundance of comammox Nitrospira clade A was mostly lower than that of clade B,whereas its diversity was mostly higher than that of clade B.Correlation analysis showed that multiple factors affected(P<0.05)the abundance of comammox Nitrospira,including soil pH,organic matter,total carbon,and total nitrogen,latitude,mean annual temperature,and mean annual precipitation.Moreover,there was a clear relationship between the comammox Nitrospira community and habitat,indicating that some amplicon sequence variants(ASVs)had a unique dominant position in specific habitats.Phylogenetic analysis showed that the ASVs of comammox Nitrospira clade A clustered with the known sequences in the paddy soils and were significantly different from the known sequences in other habitats,which may be related to the unique paddy field habitat.In contrast,comammox Nitrospira clade B showed no clear habitat dependence.These results support the wide distribution and high abundance of comammox Nitrospira in paddy soils and provide novel insights into nitrogen cycling and nutrient management in agricultural ecosystems. 展开更多
关键词 ammonia-oxidizing archaea ammonia-oxidizing bacteria amplicon sequence variant complete ammonia oxidizer environmental factor HABITAT NITRIFICATION nitrogen cycling
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Overlooked nitrogen-cycling microorganisms in biological wastewater treatment 被引量:6
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作者 Shaoyi Xu Xiaolong Wu Huijie Lu 《Frontiers of Environmental Science & Engineering》 SCIE EI CSCD 2021年第6期187-199,共13页
Nitrogen-cycling microorganisms play key roles at the intersection of microbiology and wastewater engineering.In addition to the well-studied ammonia oxidizing bacteria,nitrite oxidizing bacteria,heterotrophic denitri... Nitrogen-cycling microorganisms play key roles at the intersection of microbiology and wastewater engineering.In addition to the well-studied ammonia oxidizing bacteria,nitrite oxidizing bacteria,heterotrophic denitrifiers,and anammox bacteria,there are some other N-cycling microorganisms that are less abundant but functionally important in wastewater nitrogen removal.These microbes include,but not limited to ammonia oxidizing archaea(AOA),complete ammonia oxidation(comammox)bacteria,dissimilatory nitrate reduction to ammonia(DNRA)bacteria,and nitrate/nitrite-dependent anaerobic methane oxidizing(NO_(x)-DAMO)microorganisms.In the past decade,the development of high-throughput molecular technologies has enabled the detection,quantification,and characterization of these minor populations.The aim of this review is therefore to synthesize the current knowledge on the distribution,ecological niche,and kinetic properties of these“overlooked”N-cycling microbes at wastewater treatment plants.Their potential applications in novel wastewater nitrogen removal processes are also discussed.A comprehensive understanding of these overlooked N-cycling microbes from microbiology,ecology,and engineering perspectives will facilitate the design and operation of more efficient and sustainable biological nitrogen removal processes. 展开更多
关键词 Ammonia oxidizing archaea(AOA) complete ammonia oxidizing(comammox)bacteria Dissimilatory nitrate reduction to ammonium(DNRA)bacteria Nitrate/nitrite-dependent anaerobic methane oxidizing(NOx-DAMO)microorganisms Engineering application
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