Important effects exist between precious metals and rare earths oxides in three-way catalyst, especially the coordinated effects. These effects were studied by using H2PtCl6, Pt(NH3)2(NO2)2 and Pt(OH)2(C2H5ONH2)2 as P...Important effects exist between precious metals and rare earths oxides in three-way catalyst, especially the coordinated effects. These effects were studied by using H2PtCl6, Pt(NH3)2(NO2)2 and Pt(OH)2(C2H5ONH2)2 as Pt precursors, and the mixed oxide of (Ce-Zr-La-Pr)O as base material to prepare a series of catalysts, and their performances of the catalysts were studied by TPR and CO pulse titration technologies. The results shown that Pt precursors and their solutions pH values influenced the oxygen storage capabilities, the active metal distribution degrees of the catalysts obviously, and every catalyst prepared by different precursors had an optimal pH values. It indicates that the active metals precursors and their solutions acidities have outstanding influences on the catalysts performances for the mutual effects existing between the active metals and the Rare Earth metal oxides, which results from the mate groups of the precursors and the solution acidity.展开更多
Ammonia selective catalytic reduction(NH_(3)-SCR)is the most widely used technology in thefield of industrialflue gas denitrification.However,the presence of heavy metals influe gas can seriously affect the performance of...Ammonia selective catalytic reduction(NH_(3)-SCR)is the most widely used technology in thefield of industrialflue gas denitrification.However,the presence of heavy metals influe gas can seriously affect the performance of SCR catalysts,leading to their deactivation or even failure.Therefore,it is of great significance to deeply study the poisoning mechanism of SCR catalysts under the action of heavy metals and how to enhance their resistance to poisoning.This article reviews the reaction mechanism of NH_(3)-SCR technology,compares the impact of heavy metals on the activity of different SCR catalysts,and then discusses in detail the poisoning mechanism of SCR catalysts by heavy metals,including pore blockage,reduction of specific surface area,and destruction of active centers caused by heavy metal deposition,all of which jointly lead to the physical or chemical poisoning of the catalyst.Meanwhile,the mechanism of action when multiple toxicants coexist was analyzed.To effectively address these challenges,the article further summarizes various methods to improve the catalyst's resistance to heavy metal poisoning,such as element doping,structural optimization,and carrier addition,which significantly enhance the heavy metal resistance of the catalyst.Finally,the article provides a prospective analysis of the challenges faced by NH_(3)-SCR catalysts in anti-heavy metal poisoning technology,emphasizing the necessity of in-depth research on the poisoning mechanism,exploration of the mechanism of synergistic action of multiple pollutants,development of comprehensive anti-poisoning strategies,and research on catalyst regeneration technology,in order to promote the development of efficient anti-heavy metal poisoning NH_(3)-SCR catalysts.展开更多
The bimetallic catalysts prepared from SiO_2-supported Ru-Co,Ru- Fe and Ru-Mo carbonyl clusters exhibited high yields and selectivities towards oxygenates such as C_1-C_5 from CO+H_2,in contrast to the catalysts prepa...The bimetallic catalysts prepared from SiO_2-supported Ru-Co,Ru- Fe and Ru-Mo carbonyl clusters exhibited high yields and selectivities towards oxygenates such as C_1-C_5 from CO+H_2,in contrast to the catalysts prepared from homometallic and bimetallic Ru,Ru-Ni,Ru-Rh,Ru-Mn,and Ru- Cr carbonyl clusters.The FTIR investigation revealed that the 1584 cm^(-1) species plays an important role in the formation of oxygenates in CO hydrogenation,which is possibly assigned to surface formyl species.展开更多
The electronic modification effect of various metal oxides over Pt-Al;O;catalyst andthe relationships between the polarizing force of cations（PFC）and the electrophiliccharacter（EC）and catalytic performances（CP）o...The electronic modification effect of various metal oxides over Pt-Al;O;catalyst andthe relationships between the polarizing force of cations（PFC）and the electrophiliccharacter（EC）and catalytic performances（CP）of promoted Pt catalyst have been studiecby competitive hydrogenation reaction method（CHRM）and test reaction,i.e.hydrogena-tion of benzene and hydrogenolysis of cyclopentane.展开更多
The Cu-Mn catalysts doped with different amounts of lanthanum（La） for water-gas shift reaction（WGSR） were prepared, and characterized by X-ray diffraction（XRD）, temperature-programmed reduction（TPR）, temperatu...The Cu-Mn catalysts doped with different amounts of lanthanum（La） for water-gas shift reaction（WGSR） were prepared, and characterized by X-ray diffraction（XRD）, temperature-programmed reduction（TPR）, temperature-programmed reduction of oxidized surfaces（s-TPR）, temperature-programmed desorption of CO_2（CO_2-TPD）, infrared spectrum（FT-IR） and X-ray photoelectron spectroscopy（XPS）. Catalytic activities were tested for a water-gas shift reaction. The results showed that the introduction of 0.5 mol.% La could significantly improve the catalyst activity for low-temperature shift reaction compared with the undoped catalyst, which might be from the introduction of La making the Cu and Mn components distribute uniformly and the synergistic effect between Cu and Mn increasing the dispersion of Cu on the surface of the catalyst. The apparent CuO phases besides Cu_（1.5）Mn_（1.5）O_4 were found in the samples with at least 3.0 mol.% La content, and the basic sites increased with the increasing of La contents at a decreased rate. With excessive La doping, La particles would aggregate and cover some active sites, resulting in that Mn could not effectively inhibit the gathering together and growing up of Cu crystalline grain, and decreased the dispersion of Cu on the surface, which resulted in the poor activity of the catalyst for WGSR.展开更多
Formic acid（FA） dehydrogenation has attracted a lot of attentions since it is a convenient method for H_2 production. In this work, we designed a self-supporting fuel cell system, in which H_2 from FA is supplied in...Formic acid（FA） dehydrogenation has attracted a lot of attentions since it is a convenient method for H_2 production. In this work, we designed a self-supporting fuel cell system, in which H_2 from FA is supplied into the fuel cell, and the exhaust heat from the fuel cell supported the FA dehydrogenation. In order to realize the system, we synthesized a highly active and selective homogeneous catalyst Ir Cp＊Cl_2 bpym for FA dehydrogenation. The turnover frequency（TOF） of the catalyst for FA dehydrogenation is as high as7150 h^（-1）at 50°C, and is up to 144,000 h^（-1）at 90°C. The catalyst also shows excellent catalytic stability for FA dehydrogenation after several cycles of test. The conversion ratio of FA can achieve 93.2%, and no carbon monoxide is detected in the evolved gas. Therefore, the evolved gas could be applied in the proton exchange membrane fuel cell（PEMFC） directly. This is a potential technology for hydrogen storage and generation. The power density of the PEMFC driven by the evolved gas could approximate to that using pure hydrogen.展开更多
CONSPECTUS:The activation of C-H bonds in light alkanes efficiently is a challenging yet crucial aspect of heterogeneous catalysis.This process is essential for converting abundant hydrocarbon feedstocks into valuable...CONSPECTUS:The activation of C-H bonds in light alkanes efficiently is a challenging yet crucial aspect of heterogeneous catalysis.This process is essential for converting abundant hydrocarbon feedstocks into valuable products.The non-oxidative propane dehydrogenation to propene(PDH)has attracted widespread attention due to the presence of cheap propane in shale and has become the basis of an important on-purpose technology to bridge the gap between propene production and demand.It is also an important model reaction for studying the fundamentals of C-H bond activation.Compared to traditional oil-based cracking processes,the PDH reaction has the following advantages:(1)abundant propane recourses,mainly from shale gas and refinery plants,(2)high selectivity to propene(above 90%),and(3)the composition of the products is simple and easy to separate.Currently,commercial PDH processes rely on the Catofin and Oleflex technologies developed by CB&I Lummus and UOP Company,which apply PtSn/γ-Al_(2)O_(3)and K-CrO_(x)/γ-Al_(2)O_(3)catalysts,respectively.However,Pt-based catalysts are expensive and Cr(VI)O_(x)-based catalysts are toxic,limiting their application to a certain degree.Therefore,the search for environmentally friendly and costeffective PDH catalysts has become a key topic of ongoing research.In this Account,we will summarize the research progress on the development of ecofriendly and cost-efficient bulk ZrO_(2)-based catalysts for PDH reaction in our collaborative group during the last ten years.Their productivity and propene selectivity are very close to those of commercial-like CrO_(x)-based catalysts.These alternative-type PDH catalysts were first introduced by us.We have also elucidated the fundaments relevant to controlling their activity and product selectivity.Our novel concept inspired other research groups to develop catalysts based on other typically nonreducible metal oxides.This Account will mainly focus on the structural regulations of ZrO_(2)-based catalysts,which influence the C-H bond activation pathways as well as propene selectivity,catalyst activity,on-stream stability,and durability in the PDH reaction.First,the mechanistic aspects of propene and byproduct formation are briefly described to guide catalyst development.Second,we present the strategies used to regulate the PDH performance of ZrO_(2)-based catalysts and provide molecular level details of propene and hydrogen formation.Our approaches were aimed at(1)controlling the crystallite size,phase composition,and morphology of bare ZrO_(2),(2)constructing binary MZrO_(x)catalyst systems,such as LaZrO_(x),YZrO_(x),CrZrO_(x),and GaZrO_(x),and(3)introducing metal or metal oxide components on the surface of ZrO_(2)-based materials.Furthermore,the effects of operating conditions such as reaction temperature,catalyst treatment temperature and duration,kind of reducing agent,and H2 co-feeding on catalyst performance are discussed.The comparison between ZrO_(2)-based catalysts and other bulk metal oxide catalysts such as Al_(2)O_(3)is also discussed in terms of catalytic performance,active site,and regulation strategies.Finally,our personal views on strategies to improve the PDH performance of metal oxide-based catalysts are provided.The achievements summarized in this Account are expected to inspire further developments of catalysts used not only for efficient C-H bond activation but also for various hydrogenation reactions.展开更多
Two-dimensional(2D)materials such as metal chalcogenides have great potential as cathode catalyst materials for lithium oxygen batteries(LOBs)due to their large specific surface area and stable chemical properties.How...Two-dimensional(2D)materials such as metal chalcogenides have great potential as cathode catalyst materials for lithium oxygen batteries(LOBs)due to their large specific surface area and stable chemical properties.However,thus far,due to the lack of theoretical prediction methods,huge load on catalytic synthesis and performance evaluation is concerned.Herein,we reported a theoretical method for 2D metal chalcogenides as catalysts for LOBs using first principles density functional theory(DFT)calculations.We extracted key parameters that affect the overpotential,including Li-X bond energy(X represents chalcogen elements)and catalyst lattice constant,and theoretically predicted the catalytic performance.The DFT calculation results indicate that MoS_(2)with appropriate Li-X bond energy and lattice constant has the lowest theoretical overpotential,and its cyclic stability should be higher than other materials under the same conditions.Significantly,we experimentally validated the theoretical predictions presented above.The experimental results shows that pure MoS_(2)with 2H phase can stably work for more than 220 cycles at a current density of 500 mA/g,and the actual overpotential is lower than other metal chalcogenides.This work provides a swift pathway to accelerate searching high performance catalytic in LOBs.展开更多
基金Project supported by the National High Technology Research and Development Programs (863 ) of China (2002 AA321060, 2004AA649040) Yunnan Province Science Technology Program (2004B0028Q)
文摘Important effects exist between precious metals and rare earths oxides in three-way catalyst, especially the coordinated effects. These effects were studied by using H2PtCl6, Pt(NH3)2(NO2)2 and Pt(OH)2(C2H5ONH2)2 as Pt precursors, and the mixed oxide of (Ce-Zr-La-Pr)O as base material to prepare a series of catalysts, and their performances of the catalysts were studied by TPR and CO pulse titration technologies. The results shown that Pt precursors and their solutions pH values influenced the oxygen storage capabilities, the active metal distribution degrees of the catalysts obviously, and every catalyst prepared by different precursors had an optimal pH values. It indicates that the active metals precursors and their solutions acidities have outstanding influences on the catalysts performances for the mutual effects existing between the active metals and the Rare Earth metal oxides, which results from the mate groups of the precursors and the solution acidity.
基金supported by National Natural Science Foundation of China(U20A20130)Fundamental Research Funds for the Central Universities(FRF-EYIT-23-07).
文摘Ammonia selective catalytic reduction(NH_(3)-SCR)is the most widely used technology in thefield of industrialflue gas denitrification.However,the presence of heavy metals influe gas can seriously affect the performance of SCR catalysts,leading to their deactivation or even failure.Therefore,it is of great significance to deeply study the poisoning mechanism of SCR catalysts under the action of heavy metals and how to enhance their resistance to poisoning.This article reviews the reaction mechanism of NH_(3)-SCR technology,compares the impact of heavy metals on the activity of different SCR catalysts,and then discusses in detail the poisoning mechanism of SCR catalysts by heavy metals,including pore blockage,reduction of specific surface area,and destruction of active centers caused by heavy metal deposition,all of which jointly lead to the physical or chemical poisoning of the catalyst.Meanwhile,the mechanism of action when multiple toxicants coexist was analyzed.To effectively address these challenges,the article further summarizes various methods to improve the catalyst's resistance to heavy metal poisoning,such as element doping,structural optimization,and carrier addition,which significantly enhance the heavy metal resistance of the catalyst.Finally,the article provides a prospective analysis of the challenges faced by NH_(3)-SCR catalysts in anti-heavy metal poisoning technology,emphasizing the necessity of in-depth research on the poisoning mechanism,exploration of the mechanism of synergistic action of multiple pollutants,development of comprehensive anti-poisoning strategies,and research on catalyst regeneration technology,in order to promote the development of efficient anti-heavy metal poisoning NH_(3)-SCR catalysts.
文摘The bimetallic catalysts prepared from SiO_2-supported Ru-Co,Ru- Fe and Ru-Mo carbonyl clusters exhibited high yields and selectivities towards oxygenates such as C_1-C_5 from CO+H_2,in contrast to the catalysts prepared from homometallic and bimetallic Ru,Ru-Ni,Ru-Rh,Ru-Mn,and Ru- Cr carbonyl clusters.The FTIR investigation revealed that the 1584 cm^(-1) species plays an important role in the formation of oxygenates in CO hydrogenation,which is possibly assigned to surface formyl species.
文摘The electronic modification effect of various metal oxides over Pt-Al;O;catalyst andthe relationships between the polarizing force of cations（PFC）and the electrophiliccharacter（EC）and catalytic performances（CP）of promoted Pt catalyst have been studiecby competitive hydrogenation reaction method（CHRM）and test reaction,i.e.hydrogena-tion of benzene and hydrogenolysis of cyclopentane.
基金Project supported by the National Natural Science Foundation of China(21266017,21566028,21566029)Research Fund for the Doctoral Program of Higher Education of China(20111514110001)Inner Mongolia Natural Science Foundation(2014MS0220,2015BS0206)
文摘The Cu-Mn catalysts doped with different amounts of lanthanum（La） for water-gas shift reaction（WGSR） were prepared, and characterized by X-ray diffraction（XRD）, temperature-programmed reduction（TPR）, temperature-programmed reduction of oxidized surfaces（s-TPR）, temperature-programmed desorption of CO_2（CO_2-TPD）, infrared spectrum（FT-IR） and X-ray photoelectron spectroscopy（XPS）. Catalytic activities were tested for a water-gas shift reaction. The results showed that the introduction of 0.5 mol.% La could significantly improve the catalyst activity for low-temperature shift reaction compared with the undoped catalyst, which might be from the introduction of La making the Cu and Mn components distribute uniformly and the synergistic effect between Cu and Mn increasing the dispersion of Cu on the surface of the catalyst. The apparent CuO phases besides Cu_（1.5）Mn_（1.5）O_4 were found in the samples with at least 3.0 mol.% La content, and the basic sites increased with the increasing of La contents at a decreased rate. With excessive La doping, La particles would aggregate and cover some active sites, resulting in that Mn could not effectively inhibit the gathering together and growing up of Cu crystalline grain, and decreased the dispersion of Cu on the surface, which resulted in the poor activity of the catalyst for WGSR.
基金financial support granted by Ministry of Science and Technology of China(Nos.2016YFE0105700,2016YFA0200700)the National Natural Science Foundation of China(Nos.21373264,21573275)+2 种基金the Natural Science Foundation of Jiangsu Province(No.BK20150362)Suzhou Institute of Nano-tech and Nano-bionics(No.Y3AAA11004)Thousand Youth Talents Plan(No.Y3BQA11001)
文摘Formic acid（FA） dehydrogenation has attracted a lot of attentions since it is a convenient method for H_2 production. In this work, we designed a self-supporting fuel cell system, in which H_2 from FA is supplied into the fuel cell, and the exhaust heat from the fuel cell supported the FA dehydrogenation. In order to realize the system, we synthesized a highly active and selective homogeneous catalyst Ir Cp＊Cl_2 bpym for FA dehydrogenation. The turnover frequency（TOF） of the catalyst for FA dehydrogenation is as high as7150 h^（-1）at 50°C, and is up to 144,000 h^（-1）at 90°C. The catalyst also shows excellent catalytic stability for FA dehydrogenation after several cycles of test. The conversion ratio of FA can achieve 93.2%, and no carbon monoxide is detected in the evolved gas. Therefore, the evolved gas could be applied in the proton exchange membrane fuel cell（PEMFC） directly. This is a potential technology for hydrogen storage and generation. The power density of the PEMFC driven by the evolved gas could approximate to that using pure hydrogen.
基金support by the National Natural Science Foundation of China(Grant Nos.22108013,22225807)China National Petroleum Corporation(2023ZZ36)State Key Laboratory of Heavy Oil Processing,and the Beijing Institute of Technology Research Fund Program for Young Scholars is gratefully acknowledged.
文摘CONSPECTUS:The activation of C-H bonds in light alkanes efficiently is a challenging yet crucial aspect of heterogeneous catalysis.This process is essential for converting abundant hydrocarbon feedstocks into valuable products.The non-oxidative propane dehydrogenation to propene(PDH)has attracted widespread attention due to the presence of cheap propane in shale and has become the basis of an important on-purpose technology to bridge the gap between propene production and demand.It is also an important model reaction for studying the fundamentals of C-H bond activation.Compared to traditional oil-based cracking processes,the PDH reaction has the following advantages:(1)abundant propane recourses,mainly from shale gas and refinery plants,(2)high selectivity to propene(above 90%),and(3)the composition of the products is simple and easy to separate.Currently,commercial PDH processes rely on the Catofin and Oleflex technologies developed by CB&I Lummus and UOP Company,which apply PtSn/γ-Al_(2)O_(3)and K-CrO_(x)/γ-Al_(2)O_(3)catalysts,respectively.However,Pt-based catalysts are expensive and Cr(VI)O_(x)-based catalysts are toxic,limiting their application to a certain degree.Therefore,the search for environmentally friendly and costeffective PDH catalysts has become a key topic of ongoing research.In this Account,we will summarize the research progress on the development of ecofriendly and cost-efficient bulk ZrO_(2)-based catalysts for PDH reaction in our collaborative group during the last ten years.Their productivity and propene selectivity are very close to those of commercial-like CrO_(x)-based catalysts.These alternative-type PDH catalysts were first introduced by us.We have also elucidated the fundaments relevant to controlling their activity and product selectivity.Our novel concept inspired other research groups to develop catalysts based on other typically nonreducible metal oxides.This Account will mainly focus on the structural regulations of ZrO_(2)-based catalysts,which influence the C-H bond activation pathways as well as propene selectivity,catalyst activity,on-stream stability,and durability in the PDH reaction.First,the mechanistic aspects of propene and byproduct formation are briefly described to guide catalyst development.Second,we present the strategies used to regulate the PDH performance of ZrO_(2)-based catalysts and provide molecular level details of propene and hydrogen formation.Our approaches were aimed at(1)controlling the crystallite size,phase composition,and morphology of bare ZrO_(2),(2)constructing binary MZrO_(x)catalyst systems,such as LaZrO_(x),YZrO_(x),CrZrO_(x),and GaZrO_(x),and(3)introducing metal or metal oxide components on the surface of ZrO_(2)-based materials.Furthermore,the effects of operating conditions such as reaction temperature,catalyst treatment temperature and duration,kind of reducing agent,and H2 co-feeding on catalyst performance are discussed.The comparison between ZrO_(2)-based catalysts and other bulk metal oxide catalysts such as Al_(2)O_(3)is also discussed in terms of catalytic performance,active site,and regulation strategies.Finally,our personal views on strategies to improve the PDH performance of metal oxide-based catalysts are provided.The achievements summarized in this Account are expected to inspire further developments of catalysts used not only for efficient C-H bond activation but also for various hydrogenation reactions.
基金supported by the National Natural Science Foundation of China(Grant No.U21A2054,52262032,52273285,51961011,52173094)Scientific Research and Technology Development Program of Guangxi(Grant No.AA23062070).
文摘Two-dimensional(2D)materials such as metal chalcogenides have great potential as cathode catalyst materials for lithium oxygen batteries(LOBs)due to their large specific surface area and stable chemical properties.However,thus far,due to the lack of theoretical prediction methods,huge load on catalytic synthesis and performance evaluation is concerned.Herein,we reported a theoretical method for 2D metal chalcogenides as catalysts for LOBs using first principles density functional theory(DFT)calculations.We extracted key parameters that affect the overpotential,including Li-X bond energy(X represents chalcogen elements)and catalyst lattice constant,and theoretically predicted the catalytic performance.The DFT calculation results indicate that MoS_(2)with appropriate Li-X bond energy and lattice constant has the lowest theoretical overpotential,and its cyclic stability should be higher than other materials under the same conditions.Significantly,we experimentally validated the theoretical predictions presented above.The experimental results shows that pure MoS_(2)with 2H phase can stably work for more than 220 cycles at a current density of 500 mA/g,and the actual overpotential is lower than other metal chalcogenides.This work provides a swift pathway to accelerate searching high performance catalytic in LOBs.
