Single-atom catalysis,the catalysis by single-atom catalysts(SACs),has attracted considerable attention in recent years as a new frontier in the heterogeneous catalysis field.SACs have the advantages of both homogeneo...Single-atom catalysis,the catalysis by single-atom catalysts(SACs),has attracted considerable attention in recent years as a new frontier in the heterogeneous catalysis field.SACs have the advantages of both homogeneous catalysts(isolated active sites)and heterogeneous catalysts(stable and easy to separate),and are thus predicted to be able to bridge the homo-and heterogeneous catalysis.This prediction was first experimentally demonstrated in 2016.In this mini-review,we summarize the few homogeneous catalysis progresses reported recently where SACs have exhibited promising application:a)Rh/ZnO and Rh/CoO SAC have been used successfully in hydroformylation of olefin of which the activity are comparable to the homogeneous Wilkinson’s catalyst;b)a Pt/Al2O3 SAC has shown excellent performance in hydrosilylation reaction;and c)M-N-C SACs(M=Fe,Co etc.)have been applied in the activation of C–H bonds.All of these examples suggest that fabrication of suitable SACs could provide a new avenue for the heterogenization of homogeneous catalysts.These pioneering works shed new light on the recognition of single-atom catalysis in bridging the homo-and heterogeneous catalysis.展开更多
CO oxidation is of great importance in both fundamental study and industrial application.Supported noble metal catalysts are highly active for CO oxidation but suffer from the scarcity and high cost.Single-atom cataly...CO oxidation is of great importance in both fundamental study and industrial application.Supported noble metal catalysts are highly active for CO oxidation but suffer from the scarcity and high cost.Single-atom catalysts(SACs)can maximize the metal atom efficiency.Herein,ZnO nanowire(ZnO-nw)supported Rh,Au,and Pt SACs were successfully developed to investigate their CO oxidation performance.Interestingly,it was found that Rh1/ZnO-nw showed much higher activity than the other noble metals which are usually regarded as good candidates for CO oxidation.In addition,the Rh SAC possessed high stability in high-temperature CO oxidation under simulated conditions in the presence of water and hydrocarbons.The high activity and stability make Rh1/ZnO-nw promising for practical applications,especially in the automotive exhaust emission control.Theoretical calculations indicate that the CO oxidation proceeds via the Mars-van Krevelen mechanism and the lowest barrier for the rate-limiting O2 dissociation at a surface oxygen vacancy site is a key factor in determining the observed highest activity of Rh1/ZnO-nw amongst the studied SACs.展开更多
The idea that single metal atoms dispersed on a solid support can act as an efficient heterogeneous catalyst was raised in2011when single Pt atoms on an FeOx surface were reported to be active for CO oxidation and pre...The idea that single metal atoms dispersed on a solid support can act as an efficient heterogeneous catalyst was raised in2011when single Pt atoms on an FeOx surface were reported to be active for CO oxidation and preferential oxidation of CO in H2.The last six years have witnessed tremendous progress in the field of single‐atom catalysis.Here we introduce the major achievements on this topic in2015and2016.Some particular aspects of single‐atom catalysis are discussed in depth,including new approaches in single‐atom catalyst(SAC)synthesis,stable gold SACs for various reactions,the high selectivity of Pt and Pd SACs in hydrogenation,and the superior performance of non‐noble metal SACs in electrochemistry.These accomplishments will encourage more efforts by researchers to achieve the controllable fabrication of SACs and explore their potential applications.展开更多
Catalytic ethane dehydrogenation(EDH) to ethylene over Pt-based catalysts has received increasing interests in recent years as it is a potential alternative route to conventional steam cracking. However, the catalysts...Catalytic ethane dehydrogenation(EDH) to ethylene over Pt-based catalysts has received increasing interests in recent years as it is a potential alternative route to conventional steam cracking. However, the catalysts used in this reaction often suffer from rapid deactivation due to serious coke deposition and metal sintering. Herein, we reported the effects of Zn modification on the stability of Pt/Al2 O3 for EDH.The Zn-modified sample(PtZn2/Al2 O3) exhibits stable ethane conversion(20%) with over 95% ethylene selectivity. More importantly, it exhibits a significantly low deactivation rate of only 0.003 h-1 at 600 °C for70 h, which surpasses most of previously reported catalysts. Detailed characterizations including in situ FT-IR, ethylene adsorption microcalorimetry, and HAADF-STEM etc. reveal that Zn modifier reduces the number of Lewis acid sites on the catalyst surface. Moreover, it could modify Pt sites and preferentially cover the step sites, which decrease surface energy and retard the sintering of Pt particle, then prohibiting the further dehydrogenation of ethylene to ethylidyne. Consequently, the good stability is realized due to anti-sintering and the decrease of coke formation on the Pt Zn2/Al2 O3 catalyst.展开更多
Gold was supported on commercial ZnO powders(P) and homemade ZnO nanowires(NWs) by a modified deposition–precipitation method. X-ray diffraction and transmission electron microscopy investigation indicated that the s...Gold was supported on commercial ZnO powders(P) and homemade ZnO nanowires(NWs) by a modified deposition–precipitation method. X-ray diffraction and transmission electron microscopy investigation indicated that the size of the Au nanoparticles(NPs) depended strongly on the calcination temperature.The Au NPs were highly dispersed(< 5 nm) on both supports with calcination temperatures < 400 °C.However, after calcination at 600 °C the Au NPs aggregated much more severely on ZnO P than on ZnO NWs. Gold NPs epitaxially grew into the {10–10} facets of the ZnO NWs after calcination at temperatures > 400 °C. Such unique anchoring mechanism accounts for the much better experimentally observed sintering resistance. X-ray photoelectron spectra showed that Au existed as both metallic Au0 and Auδ+species in all the synthesized catalysts with or without calcination treatment; the ratios of Auδ+/Au0,however, varied, depending on the treatment conditions. Catalytic tests showed that the activity for CO oxidation strongly depended on the size of the Au NPs. After calcination at 600 °C, the specific rate for CO oxidation at room temperature decreased about 30 times on Au/ZnO P but only about 4 times on Au/ZnO NW. Stability tests demonstrated that the Au/ZnO NW catalysts had better stability for CO oxidation.展开更多
Alcohol-based disinfectants have protected people in the coronavirus disease 2019(COVID-19)pandemic,but olfactory stimuli of ethanol may evoke unpleasant memories associated with stressful situations in the devastatin...Alcohol-based disinfectants have protected people in the coronavirus disease 2019(COVID-19)pandemic,but olfactory stimuli of ethanol may evoke unpleasant memories associated with stressful situations in the devastating infectious disease.The smell of ethanol in household cleaning and disinfectant products can be covered up by the fragrance additives,and 3-hexenol is especially appreciated for the characteristic,strong odor of green plants.Industrial production of 3-hexenol relies on the selective hydrogenation of 3-hexyn-1-ol,where Lindlar catalyst is normally used for the superior selectivity.Although achieving such catalytic transformation in ethanol solution seems as a direct way to produce a disinfectant with green aroma,a popular consumer product in the post-COVID era,severe leaching of toxic Pb hinders Lindlar catalyst as a promising candidate.We find that the Fe_(2)O_(3) supported Pd single-atom catalyst is highly selective to fulfill semi-hydrogenation of 3-hexyn-1-ol in 75%ethanol,and the aforementioned household product is readily generated after filtrating the stable,solid catalyst out of reaction solution.Single-atom catalysts have been frequently utilized for fine-chemical synthesis,while in this work they make stunning debut in practical manufacture of daily used products.展开更多
Oxide-supported metal single-atom catalysts(SACs)have exhibited excellent catalytic performance for water-gas shift(WGS)reaction.Here,we report the single-atom catalyst Pt1/FeOx exhibits excellent medium temperature c...Oxide-supported metal single-atom catalysts(SACs)have exhibited excellent catalytic performance for water-gas shift(WGS)reaction.Here,we report the single-atom catalyst Pt1/FeOx exhibits excellent medium temperature catalytic performance for WGS reactions by the density functional theory(DFT)calculations and experimental results.The calculations indicate that H_(2)O molecules are easily dissociated at oxygen vacancies,and the formed*OH and*O are adsorbed on Pt1 single atoms and the adjacent O atoms,respectively.After studying four possible reaction mechanisms,it is found that the optimal WGS reaction pathway is proceeded along the carboxyl mechanism(pathway III),in which the formation of*COOH intermediates can promote the stability of Pt_(1)/FeO_(x) SAC and the easier occurrence of WGS reaction.The energy barrier of the rate-determining step during the entire reaction cycle is only 1.16 eV,showing the high activity for the medium temperature WGS reaction on Pt_(1)/FeO_(x) SAC,which was verified by experimental results.Moreover,the calculated turnover frequencies(TOFs)of CO_(2)and H_(2)formation on Pt1/FeOx at 610 K(337℃)can reach up to 1.14×10^(-3)s^(-1)·site^(-1)through carboxyl mechanism.In this work,we further expand the application potential of Pt1/FeOx SAC in WGS reaction.展开更多
Oxidative dehydrogenation of propane has been an ever-growing field for propylene production due to its exothermic properties,of which overoxidation is the major drawback,with CO and even CO_(2) as undesired by-produc...Oxidative dehydrogenation of propane has been an ever-growing field for propylene production due to its exothermic properties,of which overoxidation is the major drawback,with CO and even CO_(2) as undesired by-products.For the purpose of getting higher propylene selectivity as well as yield,herein,we report Ni single atoms supported on calcium aluminate as an efficient catalyst candidate for propane oxidative dehydrogenation.Beneficial from higher valence states of Ni1 species,it shows 2—3 times as much propylene selectivity as that of Ni nanoparticles.About 14.2%C_(3)H_(6) yield with 47.3%propylene selectivity has been achieved on Ni single atom catalyst and a good stability during 20 h test can be obtained as well.展开更多
Supported noble metal nanoparticles （including nanoclusters） are widely used in many industrial catalytic processes. While the finely dispersed nanostructures are highly active, they are usually thermodynamically un...Supported noble metal nanoparticles （including nanoclusters） are widely used in many industrial catalytic processes. While the finely dispersed nanostructures are highly active, they are usually thermodynamically unstable and tend to aggregate or sinter at elevated temperatures. This scenario is particularly true for supported nanogold catalysts because the gold nanostructures are easily sintered at high temperatures, under reaction conditions, or even during storage at ambient temperature. Here, we demonstrate that isolated Au single atoms dispersed on iron oxide nanocrystallites （Aul/FeOx） are much more sintering- resistant than Au nanostructures, and exhibit extremely high reaction stability for CO oxidation in a wide temperature range. Theoretical studies revealed that the positively charged and surface-anchored Aul atoms with high valent states formed significant covalent metal-support interactions （CMSIs）, thus providing the ultra-stability and remarkable catalytic performance. This work may provide insights and a new avenue for fabricating supported Au catalysts with ultra-high stability.展开更多
Heterogenization of the homogeneous catalysis has been studied for almost 50 years.Single-atom catalysis has the advantages of both homo-and heterogeneous catalysis.It has been proposed,and subsequently experimentally...Heterogenization of the homogeneous catalysis has been studied for almost 50 years.Single-atom catalysis has the advantages of both homo-and heterogeneous catalysis.It has been proposed,and subsequently experimentally verified that single-atom catalysis is able to bridge homo-and heterogeneous catalysis,thus providing a new avenue to realize the heterogenization of homogeneous catalysis.Alkoxycarbonylation of aryl halides is an effective method for the direct synthesis of carboxylic acid derivatives,and is commonly catalyzed by Pd-based homogeneous complexes with N/P-containing ligands and organic/inorganic base.Herein,we firstly reported that Pd1/CeO2 single-atom catalyst showed good performance in the alkoxycarbonylation of aryl iodides reaction.Under base-free and ligand-free conditions,Pd1/CeO2 single-atom catalyst can transfer different aryl iodides to corresponding products.The catalyst can be easily recovered and reused four times without significant loss of reactivity.展开更多
Selective hydrogenation of acetylene in excess ethylene is an important reaction in both fundamental study and practical application.Pd-based catalysts with high intrinsic activity are commonly employed,but usually su...Selective hydrogenation of acetylene in excess ethylene is an important reaction in both fundamental study and practical application.Pd-based catalysts with high intrinsic activity are commonly employed,but usually suffer from low selectivity.Pd single-atom catalysts(SACs)usually exhibit outstanding ethylene selectivity due to the weakπ-bonding ethylene adsorption.However,the preparation of high-loading and stable Pd SACs is still confronted with a great challenge.In this work,we report a simple strategy to fabricate Pd SACs by means of reducing conventional supported Pd catalysts at suitable temperatures to selectively encapsulate the co-existed Pd nanoparticles(NPs)/clusters.This is based on our new finding that single atoms only manifest strong metal-support interaction(SMSI)at higher reduction temperature than that of NPs/clusters.The derived Pd SACs(Pd1/CeO2 and Pd1/a-Fe2O3)were applied to acetylene selective hydrogenation,exhibiting much improved ethylene selectivity and high stability.This work offers a promising way to develop stable Pd SACs easily.展开更多
Gold-based catalysts are promising in CO preferential oxidation(CO-PROX)reaction in H_(2)-rich stream on account of their high intrinsic activity for CO elimination even at ambient temperature.However,the decrease of ...Gold-based catalysts are promising in CO preferential oxidation(CO-PROX)reaction in H_(2)-rich stream on account of their high intrinsic activity for CO elimination even at ambient temperature.However,the decrease of CO conversion at elevated temperature due to the competition of H_(2)oxidation,together with the low stability of gold nanoparticles,has posed a dear challenge.Herein,we report that Au-Cu bimetallic catalyst prepared by galvanic replacement method shows a wide temperature window for CO total conversion(30-100℃)and very good catalyst stability without deactivation in a 200-h test.Detailed characterizations combined with density functional theory(DFT)calculation reveal that the synergistic effect of Au-Cu,the electron transfer from Au to Cu,leads to not only strengthened chemisorption of CO but also weakened dissociation of H_(2),both of which are helpful in inhibiting the competition of H_(2)oxidation thus widening the temperature window for CO total conversion.展开更多
Supported metal catalysts,in which the metal is usually finely dispersed into nanoparticles(NPs)in size of a few nanometers on high-surface-area materials,are the workhorses in heterogeneous catalysis and have been ex...Supported metal catalysts,in which the metal is usually finely dispersed into nanoparticles(NPs)in size of a few nanometers on high-surface-area materials,are the workhorses in heterogeneous catalysis and have been extensively used in various key industrial processes[1].However,the surface heterogeneity arising from the uneven size distribution as well as the lower atomic efficiency derived from the presence of unexposed interior atoms of metal NPs often leads to inferior activity/selectivity.展开更多
基金supported by National Natural Science Foundation of China(21606222,21776270)Postdoctoral Science Foundation(2017M621170,2016M601350)~~
文摘Single-atom catalysis,the catalysis by single-atom catalysts(SACs),has attracted considerable attention in recent years as a new frontier in the heterogeneous catalysis field.SACs have the advantages of both homogeneous catalysts(isolated active sites)and heterogeneous catalysts(stable and easy to separate),and are thus predicted to be able to bridge the homo-and heterogeneous catalysis.This prediction was first experimentally demonstrated in 2016.In this mini-review,we summarize the few homogeneous catalysis progresses reported recently where SACs have exhibited promising application:a)Rh/ZnO and Rh/CoO SAC have been used successfully in hydroformylation of olefin of which the activity are comparable to the homogeneous Wilkinson’s catalyst;b)a Pt/Al2O3 SAC has shown excellent performance in hydrosilylation reaction;and c)M-N-C SACs(M=Fe,Co etc.)have been applied in the activation of C–H bonds.All of these examples suggest that fabrication of suitable SACs could provide a new avenue for the heterogenization of homogeneous catalysts.These pioneering works shed new light on the recognition of single-atom catalysis in bridging the homo-and heterogeneous catalysis.
基金supported by the National Natural Science Foundation of China(21606222,21776270)Liaoning Revitalization Talents Program(XLYC1807068)+1 种基金DNL Cooperation Fund,CAS(180403)US National Science Foundation under CHE-1465057~~
文摘CO oxidation is of great importance in both fundamental study and industrial application.Supported noble metal catalysts are highly active for CO oxidation but suffer from the scarcity and high cost.Single-atom catalysts(SACs)can maximize the metal atom efficiency.Herein,ZnO nanowire(ZnO-nw)supported Rh,Au,and Pt SACs were successfully developed to investigate their CO oxidation performance.Interestingly,it was found that Rh1/ZnO-nw showed much higher activity than the other noble metals which are usually regarded as good candidates for CO oxidation.In addition,the Rh SAC possessed high stability in high-temperature CO oxidation under simulated conditions in the presence of water and hydrocarbons.The high activity and stability make Rh1/ZnO-nw promising for practical applications,especially in the automotive exhaust emission control.Theoretical calculations indicate that the CO oxidation proceeds via the Mars-van Krevelen mechanism and the lowest barrier for the rate-limiting O2 dissociation at a surface oxygen vacancy site is a key factor in determining the observed highest activity of Rh1/ZnO-nw amongst the studied SACs.
基金supported by the National Natural Science Foundation of China(21606222,21303184,21573232)China Postdoctoral Science Foundation(2016M601350)+2 种基金Strategic Priority Research Program of the Chinese Academy of Sciences(XDB17020100)National Key Projects for Fundamental Research and Development of China(2016YFA0202801)Department of Science and Technology of Liaoning Province(2015020086-101)~~
文摘The idea that single metal atoms dispersed on a solid support can act as an efficient heterogeneous catalyst was raised in2011when single Pt atoms on an FeOx surface were reported to be active for CO oxidation and preferential oxidation of CO in H2.The last six years have witnessed tremendous progress in the field of single‐atom catalysis.Here we introduce the major achievements on this topic in2015and2016.Some particular aspects of single‐atom catalysis are discussed in depth,including new approaches in single‐atom catalyst(SAC)synthesis,stable gold SACs for various reactions,the high selectivity of Pt and Pd SACs in hydrogenation,and the superior performance of non‐noble metal SACs in electrochemistry.These accomplishments will encourage more efforts by researchers to achieve the controllable fabrication of SACs and explore their potential applications.
基金supported by the National Natural Science Foundation of China (NNSFC 21573232, 21576251, 21676269, 21878283)the Strategic Priority Research Program of Chinese Academy of Sciences Grant No. XDB17000000+2 种基金National Key Projects for Fundamental Research and Development of China (2016YFA0202801)The Youth Innovation Promotion Association CAS (2017223)Department of Science and Technology of Liaoning province under contract of 2015020086-101。
文摘Catalytic ethane dehydrogenation(EDH) to ethylene over Pt-based catalysts has received increasing interests in recent years as it is a potential alternative route to conventional steam cracking. However, the catalysts used in this reaction often suffer from rapid deactivation due to serious coke deposition and metal sintering. Herein, we reported the effects of Zn modification on the stability of Pt/Al2 O3 for EDH.The Zn-modified sample(PtZn2/Al2 O3) exhibits stable ethane conversion(20%) with over 95% ethylene selectivity. More importantly, it exhibits a significantly low deactivation rate of only 0.003 h-1 at 600 °C for70 h, which surpasses most of previously reported catalysts. Detailed characterizations including in situ FT-IR, ethylene adsorption microcalorimetry, and HAADF-STEM etc. reveal that Zn modifier reduces the number of Lewis acid sites on the catalyst surface. Moreover, it could modify Pt sites and preferentially cover the step sites, which decrease surface energy and retard the sintering of Pt particle, then prohibiting the further dehydrogenation of ethylene to ethylidyne. Consequently, the good stability is realized due to anti-sintering and the decrease of coke formation on the Pt Zn2/Al2 O3 catalyst.
基金financially supported by the start-up fund of the College of Liberal Arts and Sciences of Arizona State University and the Chinese Scholarship Council(CSC)
文摘Gold was supported on commercial ZnO powders(P) and homemade ZnO nanowires(NWs) by a modified deposition–precipitation method. X-ray diffraction and transmission electron microscopy investigation indicated that the size of the Au nanoparticles(NPs) depended strongly on the calcination temperature.The Au NPs were highly dispersed(< 5 nm) on both supports with calcination temperatures < 400 °C.However, after calcination at 600 °C the Au NPs aggregated much more severely on ZnO P than on ZnO NWs. Gold NPs epitaxially grew into the {10–10} facets of the ZnO NWs after calcination at temperatures > 400 °C. Such unique anchoring mechanism accounts for the much better experimentally observed sintering resistance. X-ray photoelectron spectra showed that Au existed as both metallic Au0 and Auδ+species in all the synthesized catalysts with or without calcination treatment; the ratios of Auδ+/Au0,however, varied, depending on the treatment conditions. Catalytic tests showed that the activity for CO oxidation strongly depended on the size of the Au NPs. After calcination at 600 °C, the specific rate for CO oxidation at room temperature decreased about 30 times on Au/ZnO P but only about 4 times on Au/ZnO NW. Stability tests demonstrated that the Au/ZnO NW catalysts had better stability for CO oxidation.
基金supported by the National Natural Science Foundation of China(Nos.22378079,22102210)Guangzhou Projects for Fundamental Research(No.202102020202)+1 种基金the Guangdong Provincial Key Laboratory of Plant Resources Biorefinery(No.2021GDKLPRB10)the start-up funding of Guangdong University of Technology.
文摘Alcohol-based disinfectants have protected people in the coronavirus disease 2019(COVID-19)pandemic,but olfactory stimuli of ethanol may evoke unpleasant memories associated with stressful situations in the devastating infectious disease.The smell of ethanol in household cleaning and disinfectant products can be covered up by the fragrance additives,and 3-hexenol is especially appreciated for the characteristic,strong odor of green plants.Industrial production of 3-hexenol relies on the selective hydrogenation of 3-hexyn-1-ol,where Lindlar catalyst is normally used for the superior selectivity.Although achieving such catalytic transformation in ethanol solution seems as a direct way to produce a disinfectant with green aroma,a popular consumer product in the post-COVID era,severe leaching of toxic Pb hinders Lindlar catalyst as a promising candidate.We find that the Fe_(2)O_(3) supported Pd single-atom catalyst is highly selective to fulfill semi-hydrogenation of 3-hexyn-1-ol in 75%ethanol,and the aforementioned household product is readily generated after filtrating the stable,solid catalyst out of reaction solution.Single-atom catalysts have been frequently utilized for fine-chemical synthesis,while in this work they make stunning debut in practical manufacture of daily used products.
基金the financial support from the National Natural Science Foundation of China(NSFC,Nos.22363001 and 21963005)the NSFC Center for Single-Atom Catalysis(No.22388102)+1 种基金the National Key Research and Development Program of China(No.2022YFA1503900)the Natural Science Special Foundation of Guizhou University(No.202140).
文摘Oxide-supported metal single-atom catalysts(SACs)have exhibited excellent catalytic performance for water-gas shift(WGS)reaction.Here,we report the single-atom catalyst Pt1/FeOx exhibits excellent medium temperature catalytic performance for WGS reactions by the density functional theory(DFT)calculations and experimental results.The calculations indicate that H_(2)O molecules are easily dissociated at oxygen vacancies,and the formed*OH and*O are adsorbed on Pt1 single atoms and the adjacent O atoms,respectively.After studying four possible reaction mechanisms,it is found that the optimal WGS reaction pathway is proceeded along the carboxyl mechanism(pathway III),in which the formation of*COOH intermediates can promote the stability of Pt_(1)/FeO_(x) SAC and the easier occurrence of WGS reaction.The energy barrier of the rate-determining step during the entire reaction cycle is only 1.16 eV,showing the high activity for the medium temperature WGS reaction on Pt_(1)/FeO_(x) SAC,which was verified by experimental results.Moreover,the calculated turnover frequencies(TOFs)of CO_(2)and H_(2)formation on Pt1/FeOx at 610 K(337℃)can reach up to 1.14×10^(-3)s^(-1)·site^(-1)through carboxyl mechanism.In this work,we further expand the application potential of Pt1/FeOx SAC in WGS reaction.
基金supported by the National Key Research and Development program of China(2021YFA1500503)the National Natural Science Foundation of China(21961142006,21972135)CAS Project for Young Scientists in Basic Research(YSBR-022).
文摘Oxidative dehydrogenation of propane has been an ever-growing field for propylene production due to its exothermic properties,of which overoxidation is the major drawback,with CO and even CO_(2) as undesired by-products.For the purpose of getting higher propylene selectivity as well as yield,herein,we report Ni single atoms supported on calcium aluminate as an efficient catalyst candidate for propane oxidative dehydrogenation.Beneficial from higher valence states of Ni1 species,it shows 2—3 times as much propylene selectivity as that of Ni nanoparticles.About 14.2%C_(3)H_(6) yield with 47.3%propylene selectivity has been achieved on Ni single atom catalyst and a good stability during 20 h test can be obtained as well.
文摘Supported noble metal nanoparticles （including nanoclusters） are widely used in many industrial catalytic processes. While the finely dispersed nanostructures are highly active, they are usually thermodynamically unstable and tend to aggregate or sinter at elevated temperatures. This scenario is particularly true for supported nanogold catalysts because the gold nanostructures are easily sintered at high temperatures, under reaction conditions, or even during storage at ambient temperature. Here, we demonstrate that isolated Au single atoms dispersed on iron oxide nanocrystallites （Aul/FeOx） are much more sintering- resistant than Au nanostructures, and exhibit extremely high reaction stability for CO oxidation in a wide temperature range. Theoretical studies revealed that the positively charged and surface-anchored Aul atoms with high valent states formed significant covalent metal-support interactions （CMSIs）, thus providing the ultra-stability and remarkable catalytic performance. This work may provide insights and a new avenue for fabricating supported Au catalysts with ultra-high stability.
基金financially supported by the National Natural Science Foundation of China (21776270)the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB17020100)+3 种基金China Postdoctoral Science Foundation(2017M621170)DICP Outstanding Postdoctoral Foundation(2017YB02)Liaoning Revitalization Talents Programdedicated funds for methanol conversion from DICP
文摘Heterogenization of the homogeneous catalysis has been studied for almost 50 years.Single-atom catalysis has the advantages of both homo-and heterogeneous catalysis.It has been proposed,and subsequently experimentally verified that single-atom catalysis is able to bridge homo-and heterogeneous catalysis,thus providing a new avenue to realize the heterogenization of homogeneous catalysis.Alkoxycarbonylation of aryl halides is an effective method for the direct synthesis of carboxylic acid derivatives,and is commonly catalyzed by Pd-based homogeneous complexes with N/P-containing ligands and organic/inorganic base.Herein,we firstly reported that Pd1/CeO2 single-atom catalyst showed good performance in the alkoxycarbonylation of aryl iodides reaction.Under base-free and ligand-free conditions,Pd1/CeO2 single-atom catalyst can transfer different aryl iodides to corresponding products.The catalyst can be easily recovered and reused four times without significant loss of reactivity.
基金financially supported by the National Natural Science Foundation of China(Nos.21972135,21961142006,and 51701201)CAS Project for Young Scientists in Basic Research(No.YSBR-022)the National Key Research and Development Program of China(No.2021YFA1500503)。
文摘Selective hydrogenation of acetylene in excess ethylene is an important reaction in both fundamental study and practical application.Pd-based catalysts with high intrinsic activity are commonly employed,but usually suffer from low selectivity.Pd single-atom catalysts(SACs)usually exhibit outstanding ethylene selectivity due to the weakπ-bonding ethylene adsorption.However,the preparation of high-loading and stable Pd SACs is still confronted with a great challenge.In this work,we report a simple strategy to fabricate Pd SACs by means of reducing conventional supported Pd catalysts at suitable temperatures to selectively encapsulate the co-existed Pd nanoparticles(NPs)/clusters.This is based on our new finding that single atoms only manifest strong metal-support interaction(SMSI)at higher reduction temperature than that of NPs/clusters.The derived Pd SACs(Pd1/CeO2 and Pd1/a-Fe2O3)were applied to acetylene selective hydrogenation,exhibiting much improved ethylene selectivity and high stability.This work offers a promising way to develop stable Pd SACs easily.
基金This work was financially supported by the“Transformational Technologies for Clean Energy and Demonstration”,the Strategic Priority Research Program of the Chinese Academy of Sciences(CAS,No.XDA21030900)DNL Cooperation Fund,CAS(No.DNL201903)the National Natural Science Foundation of China(No.51701201).
文摘Gold-based catalysts are promising in CO preferential oxidation(CO-PROX)reaction in H_(2)-rich stream on account of their high intrinsic activity for CO elimination even at ambient temperature.However,the decrease of CO conversion at elevated temperature due to the competition of H_(2)oxidation,together with the low stability of gold nanoparticles,has posed a dear challenge.Herein,we report that Au-Cu bimetallic catalyst prepared by galvanic replacement method shows a wide temperature window for CO total conversion(30-100℃)and very good catalyst stability without deactivation in a 200-h test.Detailed characterizations combined with density functional theory(DFT)calculation reveal that the synergistic effect of Au-Cu,the electron transfer from Au to Cu,leads to not only strengthened chemisorption of CO but also weakened dissociation of H_(2),both of which are helpful in inhibiting the competition of H_(2)oxidation thus widening the temperature window for CO total conversion.
文摘Supported metal catalysts,in which the metal is usually finely dispersed into nanoparticles(NPs)in size of a few nanometers on high-surface-area materials,are the workhorses in heterogeneous catalysis and have been extensively used in various key industrial processes[1].However,the surface heterogeneity arising from the uneven size distribution as well as the lower atomic efficiency derived from the presence of unexposed interior atoms of metal NPs often leads to inferior activity/selectivity.
