In this study,the support effects on the Pd-catalyzed semi-hydrogenation of acetylene have been investigated from the structural and kinetic perspectives.According to the results of kinetic analysis and X-ray photoele...In this study,the support effects on the Pd-catalyzed semi-hydrogenation of acetylene have been investigated from the structural and kinetic perspectives.According to the results of kinetic analysis and X-ray photoelectron spectroscopy,hydrogen temperature-programmed reduction,temperature-programmed hydride decomposition,and in situ X-ray diffraction measurements,using carbon nanotubes as support for Pd nanocatalysts with various sizes instead of a-Al_(2)O_(3) decreases the Pd^(0)3d binding energy and suppresses the formation of undesirable palladium hydride species,thus increasing the ethylene yield.Furthermore,X-ray absorption spectroscopy,high-resolution transmission electron microscopy,and C_(2)H_(4) temperature-programmed desorption studies combined with density-functional theory calculations reveal the existence of a unique Pd local environment,containing subsurface carbon atoms,that produces positive geometric effects on the acetylene conversion reaction.Therefore,tailoring the Pd local environment and electronic properties represents an effective strategy for the fabrication and design of highly active and selective Pd semi-hydrogenation catalysts.展开更多
In the course of investigating the catalytic behavior of metal complexes for ring opening metathesis polymerization of cycloolefins, metathesis, hydroformylation and selective hydrogenation of olefins experimental res...In the course of investigating the catalytic behavior of metal complexes for ring opening metathesis polymerization of cycloolefins, metathesis, hydroformylation and selective hydrogenation of olefins experimental results time and again indicate the presence of effects of macromolecular supports - the utilization of macromolecular supports increases obviously the activity, selectivity, and stability of the catalysts and so as to increase the conversion of substrates, yields of reactions, properties of formed polymers and so on. Discussed these effects on the basis of the authors' experiments. (Author abstract) 18 Refs.展开更多
Au]Cel_xZrxO2 catalysts （x = 0-0.8） were prepared by a deposition-precipitation method using Cel_xZrxO2 nanoparticles as supports with variable Ce and Zr contents. Their structures were characterized by complimentar...Au]Cel_xZrxO2 catalysts （x = 0-0.8） were prepared by a deposition-precipitation method using Cel_xZrxO2 nanoparticles as supports with variable Ce and Zr contents. Their structures were characterized by complimentary means such as X-ray diffraction, Raman, scanning trans- mission electron microscopy and X-ray photoelectron spectroscopy （XPS）. These Au catalysts possessed similar sizes and crystalline phases of Cel_xZrzO2 supports as well as similar sizes and oxidation states of Au nanoparticles. The oxidation state of Au nanoparticles was dominated by Au~ especially in CO oxidation. Their activities were examined in CO oxidation at different temperatures in the range of 303-333 K. The CO oxidation rates normalized per Au atoms increased with the increasing Ce contents, and reached the maximum value over Au/CeO2. Such change was in parallel with the change in the oxygen storage capacity values, i.e. the amounts of active oxygen species on Au/Cel_zZrzO2 catalysts. The excellent correlation between the two properties of the catalysts suggests that the intrinsic support effects on the CO oxidation rates is related to the effects on the adsorption and activation of O2 on Au/Cel_xZrxO2 catalysts. Such understanding on the support effects may be useful for designing more active Au catalysts, for example, by tuning the redox properties of oxide supports.展开更多
Structural regulation of Pd-based electrocatalytic hydrodechlorination(EHDC)catalyst for constructing high-efficient cathode materials with low noble metal content and high atom utilization is crucial but still challe...Structural regulation of Pd-based electrocatalytic hydrodechlorination(EHDC)catalyst for constructing high-efficient cathode materials with low noble metal content and high atom utilization is crucial but still challenging.Herein,a support electron inductive effect of Pd-Mn/Ni foam catalyst was proposed via in-situ Mn doping to optimize the electronic structure of the Ni foam(NF),which can inductive regulation of Pd for improving the EHDC performance.The mass activity and current efficiency of Pd-Mn/NF catalyst are 2.91 and 1.34 times superior to that of Pd/NF with 2,4-dichlorophenol as model compound,respectively.The Mn-doped interlayer optimized the electronic structure of Pd by bringing the d-state closer to the Fermi level than Pd on the NF surface,which optimizied the binding of EHDC intermediates.Additionally,the Mn-doped interlayer acted as a promoter for generating H∗and accelerating the EHDC reaction.This work presents a simple and effective regulation strategy for constructing high-efficient cathode catalyst for the EHDC of chlorinated organic compounds.展开更多
Leveraging the interplay between the metal component and the supporting material represents a cornerstone strategy for augmenting electrocatalytic efficiency,e.g.,electrocatalytic CO_(2)reduction reaction(CO_(2)RR).He...Leveraging the interplay between the metal component and the supporting material represents a cornerstone strategy for augmenting electrocatalytic efficiency,e.g.,electrocatalytic CO_(2)reduction reaction(CO_(2)RR).Herein,we employ freestanding porous carbon fibers(PCNF)as an efficacious and stable support for the uniformly distributed SnO_(2)nanoparticles(SnO_(2)PCNF),thereby capitalizing on the synergistic support effect that arises from their strong interaction.On one hand,the interaction between the SnO_(2)nanoparticles and the carbon support optimizes the electronic configuration of the active centers.This interaction leads to a noteworthy shift of the d-band center toward stronger intermediate adsorption energy,consequently lowering the energy barrier associated with CO_(2)reduction.As a result,the Sn O_(2)PCNF realizes a remarkable CO_(2)RR performance with excellent selectivity towards formate(98.1%).On the other hand,the porous carbon fibers enable the uniform and stable dispersion of SnO_(2)nanoparticles,and this superior porous structure of carbon supports can also facilitate the exposure of the SnO_(2)nanoparticles on the reaction interface to a great extent.Consequently,adequate contact between active sites,reactants,and electrolytes can significantly increase the metal utilization,eventually bringing forth a remarkable7.09 A/mg mass activity.This work might provide a useful idea for improving the utilization rate of metals in numerous electrocatalytic reactions.展开更多
Supported Ir catalysts were prepared using layered double hydrotalcite‐like materials,such as Mg_(3)Al_(1-x)Fe_(x),containing Fe and Al species in varying amounts as supports.These Ir catalysts were applied for the s...Supported Ir catalysts were prepared using layered double hydrotalcite‐like materials,such as Mg_(3)Al_(1-x)Fe_(x),containing Fe and Al species in varying amounts as supports.These Ir catalysts were applied for the selective hydrogenation of cinnamaldehyde(CAL).When x was changed from 0(Ir/Mg_(3)Al)to 1(Ir/Mg_(3)Fe),the rate of CAL hydrogenation reached a maximum at approximately x=0.25,while the selectivity to unsaturated alcohol,i.e.,cinnamyl alcohol,monotonously increased from 44.9%to 80.3%.Meanwhile,the size of the supported Ir particles did not change significantly with x,remaining at 1.7-0.2 nm,as determined by transmission electron microscopy.The chemical state of Ir and Fe species in the Ir/Mg3Al1-xFex catalysts was examined by temperature programmed reduction by H2 and X‐ray photoelectron spectroscopy.The surface of the supported Ir particles was also examined through the in‐situ diffuse reflectance infrared Fourier‐transform of a probe molecule of CO.On the basis of these characterization results,the effects of Fe doping to Mg_(3)Al on the structural and catalytic properties of Ir particles in selective CAL hydrogenation were discussed.The significant factors are the electron transfer from Fe2+in the Mg_(3)Al_(1–x)Fex support to the dispersed Ir particles and the surface geometry.展开更多
Supported manganese oxide catalysts were prepared by incipient wetness impregnation method for methane catalytic combustion, and effects of the support （Al2O3, SiO2 and TiO2） and Mn loading were investigated. These ...Supported manganese oxide catalysts were prepared by incipient wetness impregnation method for methane catalytic combustion, and effects of the support （Al2O3, SiO2 and TiO2） and Mn loading were investigated. These catalysts were characterized with N2 adsorption, X-ray diffraction, X-ray photoelectron spectroscopy and temperature-programmed reduction techniques. Methane conversion varied in a large range depending on supports or Mn loading. Al2O3 supported 15% Mn catalyst exhibited better activity toward methane catalytic oxidation. The manganese state and oxygen species played an important role in the catalytic performance,展开更多
SiO2,α-Al2O3,γ-Al2O3,ZrO2 and CeO2 were used as supports and Ag as promoter to study their effects on Pd catalysts for selective hydrogenation of acetylene.The catalysts were prepared by impregnated synthesis and ch...SiO2,α-Al2O3,γ-Al2O3,ZrO2 and CeO2 were used as supports and Ag as promoter to study their effects on Pd catalysts for selective hydrogenation of acetylene.The catalysts were prepared by impregnated synthesis and characterized by XRD,BET and TEM.The catalytic reaction was carried out in a fixed-bed reactor.Overall,the low specific surface area supports were better to increase the ethylene selectivity at high conversion rate of acetylene.Among the four Pd catalysts on low specific surface area supports,the catalyst on low specific surface area SiO2(LSA-SiO2) retained a high ethylene selectivity even at complete conversion,while the other catalysts showed significant decrease in the selectivity at complete conversion.The performance of Pd/LSA-SiO2 was important to decrease the loss of ethylene in selective hydrogenation of trace acetylene in ethylene.Addition of Ag to Pd/LSA-SiO2 significantly decreased the formation of ethane,C4 alkenes and green oil,and improved the ethylene selectivity to 90% when Pd:Ag=1:1 and 1:3(ω).When the ratio of Pd to Ag was above 1,the activity of Pd-Ag bimetallic catalyst was similar to that of Pd monometallic catalyst,and the selectivity of ethylene increased with increasing of amount of Ag.When the ratio of Pd to Ag was below 1,the activity of bimetallic catalyst decreased with increasing of amount of Ag,while the selectivity of ethylene was kept unchanged.The optimum temperature was 200-230℃ for 0.02%(ω)Pd-0.02%(ω)Ag/LSA-SiO2 to give a high ethylene selectivity and low formation of green oil.展开更多
Hydrogen purification must be done to meet the different purposes of hydrogen utilization.In the present work,it is confirmed that the catalyst Ni/CeO2 has the highest activity for total methanation(Total MET) of CO a...Hydrogen purification must be done to meet the different purposes of hydrogen utilization.In the present work,it is confirmed that the catalyst Ni/CeO2 has the highest activity for total methanation(Total MET) of CO and CO2,and is thus most suitable for hydrogen purification for ammonia synthesis.While,the catalyst Ni/ZrO2 appears the best one for selective methanation of CO(CO-SMET) in the H2-rich gas to produce clean fuel for proton exchange membrane fuel cell(PEMFC).In spite of this,the catalyst Ni/ZrO2 without adding chlorine ions as promoter is not yet capable of removing the CO in the reformate gas to below 10 ppm in a wide reaction temperature range by the way of CO-SMET.Adding chlorine ions as promoter is indeed not favorable for practical application due to its gradual loss in the catalytic reaction as proved in our previous work.Therefore,a step to decrease CO2 concentration(called as de-CO2 step) is suggested to be set prior to the CO-SMET step in this work.It is proved that such combination of de-CO2 step and CO-SMET step is efficient to achieve a deep removal of CO to below 10 ppm with a high selectivity more than 50% in a wide reaction temperature range of 220-280℃over the catalyst Ni/ZrO2 without adding chlorine ions as promoter.The combined process has potential for practical application,at least in the large-scale power plant of PEMFC.展开更多
Gold catalysts supported on Mg-Al mixed oxides for oxidative esterification of methacrolein are prepared by impregnation.Effects of the support particle size,concentration of HAuCl4 solution and Mg/Al ratio on gold lo...Gold catalysts supported on Mg-Al mixed oxides for oxidative esterification of methacrolein are prepared by impregnation.Effects of the support particle size,concentration of HAuCl4 solution and Mg/Al ratio on gold loading and catalytic properties are investigated.The catalysts are characterized by CO_(2)-TPD,EDS,XPS,STEM and XRD techniques.Catalysts with smaller support particle size show more uniform gold distribution and higher gold dispersion,resulting in a higher catalytic performance,and the uniformity of gold and the activity of the catalysts with larger support particle size can be improved by decreasing the concentration of HAuCl4 solution.The Mg/Al molar ratio has significant effect on the uniformity of gold and the activity of the catalyst,and the optimum Mg/Al molar ratio is 0.1–0.2.This study underlines the importance of engineering support particle size,concentration of HAuCl4 solution and density of adsorption sites for efficient gold loading on support by impregnation.展开更多
Aqueous-phase reforming(APR)is an attractive process to produce bio-based hydrogen from waste biomass streams,during which the catalyst stability is often challenged due to the harsh reaction conditions.In this work,t...Aqueous-phase reforming(APR)is an attractive process to produce bio-based hydrogen from waste biomass streams,during which the catalyst stability is often challenged due to the harsh reaction conditions.In this work,three Pt-based catalysts supported on C,AlO(OH),and ZrO_(2)were investigated for the APR of hydroxyacetone solution in afixed bed reactor at 225℃and 35 bar.Among them,the Pt/C catalyst showed the highest turnover frequency for H_(2)production(TOF of 8.9 molH_(2)molPt^(-1)min^(-1))and the longest catalyst stability.Over the AlO(OH)and ZrO_(2)supported Pt catalysts,the side reactions consuming H_(2),formation of coke,and Pt sintering result in a low H_(2)production and the fast catalyst deactivation.The proposed reaction pathways suggest that a promising APR catalyst should reform all oxygenates in the aqueous phase,minimize the hydrogenation of the oxygenates,maximize the WGS reaction,and inhibit the condensation and coking reactions for maximizing the hydrogen yield and a stable catalytic performance.展开更多
The effect of a wide variety of metal oxide （MOx） supports has been discussed for CO oxidation on nanoparticulate gold catalysts. By using typical co‐precipitation and deposition–precipitation methods and under id...The effect of a wide variety of metal oxide （MOx） supports has been discussed for CO oxidation on nanoparticulate gold catalysts. By using typical co‐precipitation and deposition–precipitation methods and under identical calcination conditions, supported gold catalysts were prepared on a wide variety of MOx supports, and the temperature for 50%conversion was measured to qualita‐tively evaluate the catalytic activities of these simple MOx and supported Au catalysts. Furthermore, the difference in these temperatures for the simple MOx compared to the supported Au catalysts is plotted against the metal–oxygen binding energies of the support MOx. A clear volcano‐like correla‐tion between the temperature difference and the metal–oxygen binding energies is observed. This correlation suggests that the use of MOx with appropriate metal–oxygen binding energies （300–500 kJ/atom O） greatly improves the catalytic activity of MOx by the deposition of Au NPs.展开更多
Support and maintenance of tunnel excavations during operation are critical to ensure the safety and stability of tunnels.This study proposes a specialized support technology for a railroad tunnel in western China,cha...Support and maintenance of tunnel excavations during operation are critical to ensure the safety and stability of tunnels.This study proposes a specialized support technology for a railroad tunnel in western China,characterized by substantial deformation and a limited inherent self-stabilizing capacity.The method involves the application of a foam concrete compressible layer at the inverted arch of the tunnel.The effectiveness of the foam concrete layer in mitigating the effect of the surrounding rock on the tunnel inverted arch structure is investigated by a combination of indoor tests and numerical simulations.The laboratory test results show that the train load has little effect on the compressive performance of the foamed concrete compressible layer,which indicates that the foamed concrete compressible layer can be applied in the tunnel invert.By analyzing the support effect of the established model,it is found that the foam concrete compressible layer can effectively absorb the deformation pressure generated by the surrounding rock and protect the secondary lining structure,when the compressible layer density is 500 kg/m^(3) and the thickness is set to 20 cm,the supporting effect is the best.展开更多
The mechanical effects of bolt-mesh-anchor coupling support in deep tunnels were studied by using a numerical method, based on deep tunnel coupling supporting techniques and non-linear deformation mechanical theory of...The mechanical effects of bolt-mesh-anchor coupling support in deep tunnels were studied by using a numerical method, based on deep tunnel coupling supporting techniques and non-linear deformation mechanical theory of rock mass at great depths.It is shown that the potential of a rigid bolt support can be efficiently activated through the coupling effect between a bolt-net support and the surrounding rock.It is found that the accumulated plastic energy in the surrounding rock can be sufficiently transformed by the coupling effect of a bolt-mesh-tray support.The strength of the surrounding rock mass can be mobilized to control the deforma-tion of the surrounding rock by a pre-stress and time-space effect of the anchor support.The high stress transformation effect can be realized by the mechanical coupling effect of the bolt-mesh-anchor support, whereby the force of the support and deformation of the surrounding rock tends to become uniform, leading to a sustained stability of the tunnel.展开更多
To investigate how the physicochemical properties and NH3‐selective catalytic reduction(NH3‐SCR)performance of supported ceria‐based catalysts are influenced as a function of support type,a series of CeO2/SiO2,CeO2...To investigate how the physicochemical properties and NH3‐selective catalytic reduction(NH3‐SCR)performance of supported ceria‐based catalysts are influenced as a function of support type,a series of CeO2/SiO2,CeO2/γ‐Al2O3,CeO2/ZrO2,and CeO2/TiO2catalysts were prepared.The physicochemical properties were probed by means of X‐ray diffraction,Raman spectroscopy,Brunauer‐Emmett‐Teller surface area measurements,X‐ray photoelectron spectroscopy,H2‐temperature programmed reduction,and NH3‐temperature programmed desorption.Furthermore,the supported ceria‐based catalysts'catalytic performance and H2O+SO2tolerance were evaluated by the NH3‐SCR model reaction.The results indicate that out of the supported ceria‐based catalysts studied,the CeO2/γ‐Al2O3catalyst exhibits the highest catalytic activity as a result of having a high relative Ce3+/Ce4+ratio,optimum reduction behavior,and the largest total acid site concentration.Finally,the CeO2/γ‐Al2O3catalyst also presents excellent H2O+SO2tolerance during the NH3‐SCR process.展开更多
The chemical looping process,where an oxygen carrier is reduced and oxidized in a cyclic manner,offers a promising option for hydrogen production through splitting water because of the much higher water splitting effi...The chemical looping process,where an oxygen carrier is reduced and oxidized in a cyclic manner,offers a promising option for hydrogen production through splitting water because of the much higher water splitting efficiency than solar electrocatalytic and photocatalytic process.A typical oxygen carrier has to comprise a significant amount of inert support,to maintain stability in multiple redox cycles,thereby resulting in a trade-off between the reaction reactivity and stability.Herein,we proposed the use of ion-conductive yttria-stabilized zirconia(YSZ)support Fe_(2)O_(3)to prepare oxygen carriers materials.The obtained Fe_(2)O_(3)/YSZ composites showed high reactivity and stability.Particularly,Fe_(2)O_(3)/YSZ-20(oxygen storage capacity,24.13%)exhibited high hydrogen yield of~10.30 mmol g^(-1) and hydrogen production rate of~0.66 mmol g^(-1) min^(-1) which was twice as high as that of Fe_(2)O_(3)/Al_(2)O_(3).Further,the transient pulse test indicated that active oxygen diffusion was the ratelimiting step during the redox process.The electrochemical impedance spectroscopy(EIS)measurement revealed that the YSZ support addition facilitated oxygen diffusion of materials,which contributed to the improved hydrogen production performance.The support effect obtained in this work provides a potentially efficient route for the modification of oxygen carrier materials.展开更多
Chemoselective hydrogenation of unsaturated aldehyde to unsaturated alcohol has attracted growing interests in recent years due to its widespread applications in fine chemicals.However,the hydrogenation of the C=O bon...Chemoselective hydrogenation of unsaturated aldehyde to unsaturated alcohol has attracted growing interests in recent years due to its widespread applications in fine chemicals.However,the hydrogenation of the C=O bond was thermodynamically and kinetically unfavorable over the hydrogenation of the C=C bond.Thus,to obtain the unsaturated alcohol from the unsaturated aldehyde is very difficult in most of the catalytic systems.In this work,ZnAl-hydrotalcite-supported cysteine-capped Au25 nanoclusters were used as the precatalysts for chemoselective hydrogenation of cinnamaldehyde to cinnamyl alcohol.The catalyst showed stable high selectivity(~95%)at prolonged reaction time and complete conversion of the substrate.According to the results of the control experiments,the in-situ DRIFTS of the substrate under high pressure of hydrogen and the 27Al MAS-NMR spectroscopy,we proposed that the difference of the preferential adsorption of the C=O bond to that of the C=C bond was derived from the nature of the support of the gold catalysts.展开更多
A set of mono-and bimetallic（Zn-Co） supported ZSM-5 catalysts was first prepared by PEG-additive method. The physicochemical properties of the catalysts were investigated by FTIR, XPS, XRD, N2adsorption-desorption m...A set of mono-and bimetallic（Zn-Co） supported ZSM-5 catalysts was first prepared by PEG-additive method. The physicochemical properties of the catalysts were investigated by FTIR, XPS, XRD, N2adsorption-desorption measurements, SEM, EDS and NH3-TPD techniques. The physicochemical properties showed that the Zn Co2O4 spinel oxide was formed on the ZSM-5 support and provided effectual synergetic effect between Zn and Co species for the bimetallic catalyst. Furthermore, bimetallic supported ZSM-5 catalyst exhibited weak, moderate and strong acidic sites, while the monometallic supported ZSM-5 catalyst showed only weak and moderate or strong acidic sites. Their catalytic performances for thermal decomposition of hexamethylene–1,6–dicarbamate（HDC） to hexamethylene–1,6–diisocyanate（HDI） were then studied. It was found that the bimetallic supported ZSM-5 catalysts,especially Zn-2Co/ZSM-5 catalyst showed excellent catalytic performance due to the good synergetic effect between Co and Zn species, which provided a suitable contribution of acidic sites. HDC conversion of 100% with HDI selectivity of 91.2% and by-products selectivity of 1.3% could be achieved within short reaction time of 2.5 h over Zn-2Co/ZSM-5 catalyst.展开更多
The effect of mixed oxide support on the performance of Ni/ZnO in the reactive adsorption desulfurization(RADS) reaction was investigated in a fixed bed reactor by using thiophene as the sulfur-containing compound in ...The effect of mixed oxide support on the performance of Ni/ZnO in the reactive adsorption desulfurization(RADS) reaction was investigated in a fixed bed reactor by using thiophene as the sulfur-containing compound in the model gasoline. A series of oxide supports for Ni/ZnO were synthesized by the co-precipitation method and characterized by XRD, N_2-adsorption, TPR and NH_3-TPD techniques. It was found that the desulfurization capacity of Ni/ZnO was enhanced greatly when active components were supported on the proper mixed oxide. Ni/ZnO supported on oxides exhibited much higher desulfurization efficiency and sulfur adsorption capacity than the unsupported Ni/ZnO and the synthesized Ni/ZnO-SA adsorbent exhibited the highest efficiency for thiophene removal. The higher desulfurization activity and sulfur capacity of Ni/ZnO supported on SiO_2-Al_2O_3 with small particle size, high specific surface area and large pore volume could promote the high dispersion of active metal phase and the transfer of sulfur to ZnO with lower mass transfer resistance. γ-Al_2O_3 species could weaken the interaction of active phases and SiO_2 as well as could increase greatly the amount of weak acids. Therefore, these oxides could impose a great influence on the structure and chemical properties of the catalyst.展开更多
基金This work was financially supported by the Natural Science Foundation of China(21922803,21776077,and 22008067)the Innovation Program of Shanghai Municipal Education Commission,the Shanghai Natural Science Foundation(17ZR1407300 and 17ZR1407500)+4 种基金the Program for Professor of Special Appointment(Eastern Scholar)at Shanghai Institutions of Higher Learning,the Shanghai Rising-Star Program(17QA1401200)the China Postdoctoral Science Foundation(2020M681202)the Open Project of State Key Laboratory of Chemical Engineering(SKLChe-15C03)the State Key Laboratory of Organic-Inorganic Composites(oic-201801007)the Fundamental Research Funds for the Central Universities(222201718003).
文摘In this study,the support effects on the Pd-catalyzed semi-hydrogenation of acetylene have been investigated from the structural and kinetic perspectives.According to the results of kinetic analysis and X-ray photoelectron spectroscopy,hydrogen temperature-programmed reduction,temperature-programmed hydride decomposition,and in situ X-ray diffraction measurements,using carbon nanotubes as support for Pd nanocatalysts with various sizes instead of a-Al_(2)O_(3) decreases the Pd^(0)3d binding energy and suppresses the formation of undesirable palladium hydride species,thus increasing the ethylene yield.Furthermore,X-ray absorption spectroscopy,high-resolution transmission electron microscopy,and C_(2)H_(4) temperature-programmed desorption studies combined with density-functional theory calculations reveal the existence of a unique Pd local environment,containing subsurface carbon atoms,that produces positive geometric effects on the acetylene conversion reaction.Therefore,tailoring the Pd local environment and electronic properties represents an effective strategy for the fabrication and design of highly active and selective Pd semi-hydrogenation catalysts.
基金The project was supported by the National Natural Science Foundation of China, "Macromolecular ligand effects of catalytic system for ring opening metathesis polymerization of dicydopentadiene" (Approval No. 29474160) & "Polymeric metal complex catalysts
文摘In the course of investigating the catalytic behavior of metal complexes for ring opening metathesis polymerization of cycloolefins, metathesis, hydroformylation and selective hydrogenation of olefins experimental results time and again indicate the presence of effects of macromolecular supports - the utilization of macromolecular supports increases obviously the activity, selectivity, and stability of the catalysts and so as to increase the conversion of substrates, yields of reactions, properties of formed polymers and so on. Discussed these effects on the basis of the authors' experiments. (Author abstract) 18 Refs.
基金the National Natural Science Foundation of China(20825310,20973011)the National Basic Research Program of China(973 Program,2011CB201400,2011CB808700)
文摘Au]Cel_xZrxO2 catalysts （x = 0-0.8） were prepared by a deposition-precipitation method using Cel_xZrxO2 nanoparticles as supports with variable Ce and Zr contents. Their structures were characterized by complimentary means such as X-ray diffraction, Raman, scanning trans- mission electron microscopy and X-ray photoelectron spectroscopy （XPS）. These Au catalysts possessed similar sizes and crystalline phases of Cel_xZrzO2 supports as well as similar sizes and oxidation states of Au nanoparticles. The oxidation state of Au nanoparticles was dominated by Au~ especially in CO oxidation. Their activities were examined in CO oxidation at different temperatures in the range of 303-333 K. The CO oxidation rates normalized per Au atoms increased with the increasing Ce contents, and reached the maximum value over Au/CeO2. Such change was in parallel with the change in the oxygen storage capacity values, i.e. the amounts of active oxygen species on Au/Cel_zZrzO2 catalysts. The excellent correlation between the two properties of the catalysts suggests that the intrinsic support effects on the CO oxidation rates is related to the effects on the adsorption and activation of O2 on Au/Cel_xZrxO2 catalysts. Such understanding on the support effects may be useful for designing more active Au catalysts, for example, by tuning the redox properties of oxide supports.
基金supported by the National Natural Science Foundation of China(Nos.22178388 and 22108306)Taishan Scholars Program of Shandong Province(No.tsqn201909065)Chongqing Science and Technology Bureau(No.cstc2019jscx-gksb X0032).
文摘Structural regulation of Pd-based electrocatalytic hydrodechlorination(EHDC)catalyst for constructing high-efficient cathode materials with low noble metal content and high atom utilization is crucial but still challenging.Herein,a support electron inductive effect of Pd-Mn/Ni foam catalyst was proposed via in-situ Mn doping to optimize the electronic structure of the Ni foam(NF),which can inductive regulation of Pd for improving the EHDC performance.The mass activity and current efficiency of Pd-Mn/NF catalyst are 2.91 and 1.34 times superior to that of Pd/NF with 2,4-dichlorophenol as model compound,respectively.The Mn-doped interlayer optimized the electronic structure of Pd by bringing the d-state closer to the Fermi level than Pd on the NF surface,which optimizied the binding of EHDC intermediates.Additionally,the Mn-doped interlayer acted as a promoter for generating H∗and accelerating the EHDC reaction.This work presents a simple and effective regulation strategy for constructing high-efficient cathode catalyst for the EHDC of chlorinated organic compounds.
基金supported by the National Natural Science Foundation of China(Nos.22172099,U21A20312)Guangdong Basic and Applied Basic Research Foundation(Nos.2023A1515012776,2022B1515120084)the Shenzhen Science and Technology Program(No.RCYX20200714114535052)。
文摘Leveraging the interplay between the metal component and the supporting material represents a cornerstone strategy for augmenting electrocatalytic efficiency,e.g.,electrocatalytic CO_(2)reduction reaction(CO_(2)RR).Herein,we employ freestanding porous carbon fibers(PCNF)as an efficacious and stable support for the uniformly distributed SnO_(2)nanoparticles(SnO_(2)PCNF),thereby capitalizing on the synergistic support effect that arises from their strong interaction.On one hand,the interaction between the SnO_(2)nanoparticles and the carbon support optimizes the electronic configuration of the active centers.This interaction leads to a noteworthy shift of the d-band center toward stronger intermediate adsorption energy,consequently lowering the energy barrier associated with CO_(2)reduction.As a result,the Sn O_(2)PCNF realizes a remarkable CO_(2)RR performance with excellent selectivity towards formate(98.1%).On the other hand,the porous carbon fibers enable the uniform and stable dispersion of SnO_(2)nanoparticles,and this superior porous structure of carbon supports can also facilitate the exposure of the SnO_(2)nanoparticles on the reaction interface to a great extent.Consequently,adequate contact between active sites,reactants,and electrolytes can significantly increase the metal utilization,eventually bringing forth a remarkable7.09 A/mg mass activity.This work might provide a useful idea for improving the utilization rate of metals in numerous electrocatalytic reactions.
文摘Supported Ir catalysts were prepared using layered double hydrotalcite‐like materials,such as Mg_(3)Al_(1-x)Fe_(x),containing Fe and Al species in varying amounts as supports.These Ir catalysts were applied for the selective hydrogenation of cinnamaldehyde(CAL).When x was changed from 0(Ir/Mg_(3)Al)to 1(Ir/Mg_(3)Fe),the rate of CAL hydrogenation reached a maximum at approximately x=0.25,while the selectivity to unsaturated alcohol,i.e.,cinnamyl alcohol,monotonously increased from 44.9%to 80.3%.Meanwhile,the size of the supported Ir particles did not change significantly with x,remaining at 1.7-0.2 nm,as determined by transmission electron microscopy.The chemical state of Ir and Fe species in the Ir/Mg3Al1-xFex catalysts was examined by temperature programmed reduction by H2 and X‐ray photoelectron spectroscopy.The surface of the supported Ir particles was also examined through the in‐situ diffuse reflectance infrared Fourier‐transform of a probe molecule of CO.On the basis of these characterization results,the effects of Fe doping to Mg_(3)Al on the structural and catalytic properties of Ir particles in selective CAL hydrogenation were discussed.The significant factors are the electron transfer from Fe2+in the Mg_(3)Al_(1–x)Fex support to the dispersed Ir particles and the surface geometry.
基金supported by the New Century Excellent Talent Project of China (NCET-05-0783).
文摘Supported manganese oxide catalysts were prepared by incipient wetness impregnation method for methane catalytic combustion, and effects of the support （Al2O3, SiO2 and TiO2） and Mn loading were investigated. These catalysts were characterized with N2 adsorption, X-ray diffraction, X-ray photoelectron spectroscopy and temperature-programmed reduction techniques. Methane conversion varied in a large range depending on supports or Mn loading. Al2O3 supported 15% Mn catalyst exhibited better activity toward methane catalytic oxidation. The manganese state and oxygen species played an important role in the catalytic performance,
文摘SiO2,α-Al2O3,γ-Al2O3,ZrO2 and CeO2 were used as supports and Ag as promoter to study their effects on Pd catalysts for selective hydrogenation of acetylene.The catalysts were prepared by impregnated synthesis and characterized by XRD,BET and TEM.The catalytic reaction was carried out in a fixed-bed reactor.Overall,the low specific surface area supports were better to increase the ethylene selectivity at high conversion rate of acetylene.Among the four Pd catalysts on low specific surface area supports,the catalyst on low specific surface area SiO2(LSA-SiO2) retained a high ethylene selectivity even at complete conversion,while the other catalysts showed significant decrease in the selectivity at complete conversion.The performance of Pd/LSA-SiO2 was important to decrease the loss of ethylene in selective hydrogenation of trace acetylene in ethylene.Addition of Ag to Pd/LSA-SiO2 significantly decreased the formation of ethane,C4 alkenes and green oil,and improved the ethylene selectivity to 90% when Pd:Ag=1:1 and 1:3(ω).When the ratio of Pd to Ag was above 1,the activity of Pd-Ag bimetallic catalyst was similar to that of Pd monometallic catalyst,and the selectivity of ethylene increased with increasing of amount of Ag.When the ratio of Pd to Ag was below 1,the activity of bimetallic catalyst decreased with increasing of amount of Ag,while the selectivity of ethylene was kept unchanged.The optimum temperature was 200-230℃ for 0.02%(ω)Pd-0.02%(ω)Ag/LSA-SiO2 to give a high ethylene selectivity and low formation of green oil.
基金Project supported by the National Natural Science Foundation of China(21643008)
文摘Hydrogen purification must be done to meet the different purposes of hydrogen utilization.In the present work,it is confirmed that the catalyst Ni/CeO2 has the highest activity for total methanation(Total MET) of CO and CO2,and is thus most suitable for hydrogen purification for ammonia synthesis.While,the catalyst Ni/ZrO2 appears the best one for selective methanation of CO(CO-SMET) in the H2-rich gas to produce clean fuel for proton exchange membrane fuel cell(PEMFC).In spite of this,the catalyst Ni/ZrO2 without adding chlorine ions as promoter is not yet capable of removing the CO in the reformate gas to below 10 ppm in a wide reaction temperature range by the way of CO-SMET.Adding chlorine ions as promoter is indeed not favorable for practical application due to its gradual loss in the catalytic reaction as proved in our previous work.Therefore,a step to decrease CO2 concentration(called as de-CO2 step) is suggested to be set prior to the CO-SMET step in this work.It is proved that such combination of de-CO2 step and CO-SMET step is efficient to achieve a deep removal of CO to below 10 ppm with a high selectivity more than 50% in a wide reaction temperature range of 220-280℃over the catalyst Ni/ZrO2 without adding chlorine ions as promoter.The combined process has potential for practical application,at least in the large-scale power plant of PEMFC.
基金Open Project of Yunnan Precious Metals Laboratory Co.,Ltd(YPML-2023050269)the Fundamental Research Funds for the Central Universities(226-2023-00085,226-2023-00057).
文摘Gold catalysts supported on Mg-Al mixed oxides for oxidative esterification of methacrolein are prepared by impregnation.Effects of the support particle size,concentration of HAuCl4 solution and Mg/Al ratio on gold loading and catalytic properties are investigated.The catalysts are characterized by CO_(2)-TPD,EDS,XPS,STEM and XRD techniques.Catalysts with smaller support particle size show more uniform gold distribution and higher gold dispersion,resulting in a higher catalytic performance,and the uniformity of gold and the activity of the catalysts with larger support particle size can be improved by decreasing the concentration of HAuCl4 solution.The Mg/Al molar ratio has significant effect on the uniformity of gold and the activity of the catalyst,and the optimum Mg/Al molar ratio is 0.1–0.2.This study underlines the importance of engineering support particle size,concentration of HAuCl4 solution and density of adsorption sites for efficient gold loading on support by impregnation.
基金support from European Union Seventh Frame-work Programme(FP7/2007-2013 project SusFuelCat,grant No.310490)is acknowledged.
文摘Aqueous-phase reforming(APR)is an attractive process to produce bio-based hydrogen from waste biomass streams,during which the catalyst stability is often challenged due to the harsh reaction conditions.In this work,three Pt-based catalysts supported on C,AlO(OH),and ZrO_(2)were investigated for the APR of hydroxyacetone solution in afixed bed reactor at 225℃and 35 bar.Among them,the Pt/C catalyst showed the highest turnover frequency for H_(2)production(TOF of 8.9 molH_(2)molPt^(-1)min^(-1))and the longest catalyst stability.Over the AlO(OH)and ZrO_(2)supported Pt catalysts,the side reactions consuming H_(2),formation of coke,and Pt sintering result in a low H_(2)production and the fast catalyst deactivation.The proposed reaction pathways suggest that a promising APR catalyst should reform all oxygenates in the aqueous phase,minimize the hydrogenation of the oxygenates,maximize the WGS reaction,and inhibit the condensation and coking reactions for maximizing the hydrogen yield and a stable catalytic performance.
文摘The effect of a wide variety of metal oxide （MOx） supports has been discussed for CO oxidation on nanoparticulate gold catalysts. By using typical co‐precipitation and deposition–precipitation methods and under identical calcination conditions, supported gold catalysts were prepared on a wide variety of MOx supports, and the temperature for 50%conversion was measured to qualita‐tively evaluate the catalytic activities of these simple MOx and supported Au catalysts. Furthermore, the difference in these temperatures for the simple MOx compared to the supported Au catalysts is plotted against the metal–oxygen binding energies of the support MOx. A clear volcano‐like correla‐tion between the temperature difference and the metal–oxygen binding energies is observed. This correlation suggests that the use of MOx with appropriate metal–oxygen binding energies （300–500 kJ/atom O） greatly improves the catalytic activity of MOx by the deposition of Au NPs.
基金supported by the National Natural Science Foundation of China under grant number 52179113Open Research Fund of State Key Laboratory of Geomechanics and Geotechnical Engineering Safety Grant No.SKLGME 022022,SKLGME-JBGS2401.
文摘Support and maintenance of tunnel excavations during operation are critical to ensure the safety and stability of tunnels.This study proposes a specialized support technology for a railroad tunnel in western China,characterized by substantial deformation and a limited inherent self-stabilizing capacity.The method involves the application of a foam concrete compressible layer at the inverted arch of the tunnel.The effectiveness of the foam concrete layer in mitigating the effect of the surrounding rock on the tunnel inverted arch structure is investigated by a combination of indoor tests and numerical simulations.The laboratory test results show that the train load has little effect on the compressive performance of the foamed concrete compressible layer,which indicates that the foamed concrete compressible layer can be applied in the tunnel invert.By analyzing the support effect of the established model,it is found that the foam concrete compressible layer can effectively absorb the deformation pressure generated by the surrounding rock and protect the secondary lining structure,when the compressible layer density is 500 kg/m^(3) and the thickness is set to 20 cm,the supporting effect is the best.
基金Projects 2006CB202200 supported by the National Basic Research Program of ChinaNCET07-0800 by the Program for New Century Excellent Talents in Universities
文摘The mechanical effects of bolt-mesh-anchor coupling support in deep tunnels were studied by using a numerical method, based on deep tunnel coupling supporting techniques and non-linear deformation mechanical theory of rock mass at great depths.It is shown that the potential of a rigid bolt support can be efficiently activated through the coupling effect between a bolt-net support and the surrounding rock.It is found that the accumulated plastic energy in the surrounding rock can be sufficiently transformed by the coupling effect of a bolt-mesh-tray support.The strength of the surrounding rock mass can be mobilized to control the deforma-tion of the surrounding rock by a pre-stress and time-space effect of the anchor support.The high stress transformation effect can be realized by the mechanical coupling effect of the bolt-mesh-anchor support, whereby the force of the support and deformation of the surrounding rock tends to become uniform, leading to a sustained stability of the tunnel.
基金supported by the National Natural Science Foundation of China (21507130)the Chongqing Science and Technology Commission (cstc2016jcyjA 0070,cstc2014pt-gc20002,cstc2014yykfC 20003,cstckjcxljrc13)the Open Project Program of Chongqing Key Laboratory of Ca-talysis and Functional Organic Molecules from Chongqing Technology and Business University (1456029)~~
文摘To investigate how the physicochemical properties and NH3‐selective catalytic reduction(NH3‐SCR)performance of supported ceria‐based catalysts are influenced as a function of support type,a series of CeO2/SiO2,CeO2/γ‐Al2O3,CeO2/ZrO2,and CeO2/TiO2catalysts were prepared.The physicochemical properties were probed by means of X‐ray diffraction,Raman spectroscopy,Brunauer‐Emmett‐Teller surface area measurements,X‐ray photoelectron spectroscopy,H2‐temperature programmed reduction,and NH3‐temperature programmed desorption.Furthermore,the supported ceria‐based catalysts'catalytic performance and H2O+SO2tolerance were evaluated by the NH3‐SCR model reaction.The results indicate that out of the supported ceria‐based catalysts studied,the CeO2/γ‐Al2O3catalyst exhibits the highest catalytic activity as a result of having a high relative Ce3+/Ce4+ratio,optimum reduction behavior,and the largest total acid site concentration.Finally,the CeO2/γ‐Al2O3catalyst also presents excellent H2O+SO2tolerance during the NH3‐SCR process.
基金the National Natural Science Foundation of China(Grant No.51906041)the Natural Science Foundation of Jiangsu Province(Grant NO.BK20190360)the National Science Foundation for Distinguished Young Scholars of China(Grant No.51525601)。
文摘The chemical looping process,where an oxygen carrier is reduced and oxidized in a cyclic manner,offers a promising option for hydrogen production through splitting water because of the much higher water splitting efficiency than solar electrocatalytic and photocatalytic process.A typical oxygen carrier has to comprise a significant amount of inert support,to maintain stability in multiple redox cycles,thereby resulting in a trade-off between the reaction reactivity and stability.Herein,we proposed the use of ion-conductive yttria-stabilized zirconia(YSZ)support Fe_(2)O_(3)to prepare oxygen carriers materials.The obtained Fe_(2)O_(3)/YSZ composites showed high reactivity and stability.Particularly,Fe_(2)O_(3)/YSZ-20(oxygen storage capacity,24.13%)exhibited high hydrogen yield of~10.30 mmol g^(-1) and hydrogen production rate of~0.66 mmol g^(-1) min^(-1) which was twice as high as that of Fe_(2)O_(3)/Al_(2)O_(3).Further,the transient pulse test indicated that active oxygen diffusion was the ratelimiting step during the redox process.The electrochemical impedance spectroscopy(EIS)measurement revealed that the YSZ support addition facilitated oxygen diffusion of materials,which contributed to the improved hydrogen production performance.The support effect obtained in this work provides a potentially efficient route for the modification of oxygen carrier materials.
文摘Chemoselective hydrogenation of unsaturated aldehyde to unsaturated alcohol has attracted growing interests in recent years due to its widespread applications in fine chemicals.However,the hydrogenation of the C=O bond was thermodynamically and kinetically unfavorable over the hydrogenation of the C=C bond.Thus,to obtain the unsaturated alcohol from the unsaturated aldehyde is very difficult in most of the catalytic systems.In this work,ZnAl-hydrotalcite-supported cysteine-capped Au25 nanoclusters were used as the precatalysts for chemoselective hydrogenation of cinnamaldehyde to cinnamyl alcohol.The catalyst showed stable high selectivity(~95%)at prolonged reaction time and complete conversion of the substrate.According to the results of the control experiments,the in-situ DRIFTS of the substrate under high pressure of hydrogen and the 27Al MAS-NMR spectroscopy,we proposed that the difference of the preferential adsorption of the C=O bond to that of the C=C bond was derived from the nature of the support of the gold catalysts.
基金supported by National Natural Science Foundation of China(Nos.21476244 and 21406245)Youth Innovation Promotion Association CAS
文摘A set of mono-and bimetallic（Zn-Co） supported ZSM-5 catalysts was first prepared by PEG-additive method. The physicochemical properties of the catalysts were investigated by FTIR, XPS, XRD, N2adsorption-desorption measurements, SEM, EDS and NH3-TPD techniques. The physicochemical properties showed that the Zn Co2O4 spinel oxide was formed on the ZSM-5 support and provided effectual synergetic effect between Zn and Co species for the bimetallic catalyst. Furthermore, bimetallic supported ZSM-5 catalyst exhibited weak, moderate and strong acidic sites, while the monometallic supported ZSM-5 catalyst showed only weak and moderate or strong acidic sites. Their catalytic performances for thermal decomposition of hexamethylene–1,6–dicarbamate（HDC） to hexamethylene–1,6–diisocyanate（HDI） were then studied. It was found that the bimetallic supported ZSM-5 catalysts,especially Zn-2Co/ZSM-5 catalyst showed excellent catalytic performance due to the good synergetic effect between Co and Zn species, which provided a suitable contribution of acidic sites. HDC conversion of 100% with HDI selectivity of 91.2% and by-products selectivity of 1.3% could be achieved within short reaction time of 2.5 h over Zn-2Co/ZSM-5 catalyst.
基金financially supported by the National Natural Science Foundation of China(No.21276086)
文摘The effect of mixed oxide support on the performance of Ni/ZnO in the reactive adsorption desulfurization(RADS) reaction was investigated in a fixed bed reactor by using thiophene as the sulfur-containing compound in the model gasoline. A series of oxide supports for Ni/ZnO were synthesized by the co-precipitation method and characterized by XRD, N_2-adsorption, TPR and NH_3-TPD techniques. It was found that the desulfurization capacity of Ni/ZnO was enhanced greatly when active components were supported on the proper mixed oxide. Ni/ZnO supported on oxides exhibited much higher desulfurization efficiency and sulfur adsorption capacity than the unsupported Ni/ZnO and the synthesized Ni/ZnO-SA adsorbent exhibited the highest efficiency for thiophene removal. The higher desulfurization activity and sulfur capacity of Ni/ZnO supported on SiO_2-Al_2O_3 with small particle size, high specific surface area and large pore volume could promote the high dispersion of active metal phase and the transfer of sulfur to ZnO with lower mass transfer resistance. γ-Al_2O_3 species could weaken the interaction of active phases and SiO_2 as well as could increase greatly the amount of weak acids. Therefore, these oxides could impose a great influence on the structure and chemical properties of the catalyst.
