In this work,the surface properties of CeO_(2)-supported Cu catalysts were adjusted via doping Mn or/and Co with different ratios(CuMnaCO_(1-a)/Ce,a=0,0.25,0.5,0.75 and 1).The roles of metallic effects on the activiti...In this work,the surface properties of CeO_(2)-supported Cu catalysts were adjusted via doping Mn or/and Co with different ratios(CuMnaCO_(1-a)/Ce,a=0,0.25,0.5,0.75 and 1).The roles of metallic effects on the activities,structures and reaction pathways of the catalysts were investigated using various characterization techniques.The results reveal the CuMnCo/Ce catalysts show better performance,followed by Cu/Ce and MnCo/Ce.Among CuMnCo/Ce catalysts,the CuMn_(0.25)Co_(0.75)/Ce exhibits the excellent activity under a higher gas hourly space velocity.The improved surface properties mainly involve the higher dispersion of CuOxand stronger redox cycle due to Co substitution,and more active oxygen species(oxygen vacancies and activated lattice oxygen)contributed by Mn substitution.From the in situ infrared spectroscopy(in situ IR)experiments,the electron transfer of Cu and Co can strengthen the adsorption of CO on Cu species indirectly,whereas,more oxygen defects coming from the Mn-OV-Ce structure boost the activation of oxygen species,the formation of carbonate intermediates and then the release of CO_(2).This work may guide the simple regulation of active sites and the utilization of the catalytic potential of Cu-Ce oxide catalysts.展开更多
Carbon monoxide(CO)oxidation is crucial for pollutant removal and hydrogen purification.In recent years,copper–cerium(Cu–Ce)-mixed oxide catalysts have attracted significant attention due to their excellent activity a...Carbon monoxide(CO)oxidation is crucial for pollutant removal and hydrogen purification.In recent years,copper–cerium(Cu–Ce)-mixed oxide catalysts have attracted significant attention due to their excellent activity and stability in CO oxida-tion.This study presents an innovative,environmentally friendly electrosynthesis method for producing stable,structured Cu–Ce catalysts in mesh form.This approach addresses the limitations of traditional pellet catalysts,such as fragility and poor thermal conductivity.The results demonstrated that incorporating cerium(Ce)enhanced the catalytic activity for CO oxidation threefold.A series of in situ characterizations revealed that the introduction of Ce led to the formation of a Cu–Ce mixed oxide solid solution,which significantly improved catalytic performance.Furthermore,higher pretreatment tem-peratures facilitated the decomposition of Ce compounds(nitrate and hydroxide),which promotes the formation of Cu–Ce solid solutions and increases the concentration of active intermediate species(Cu^(+)-CO)during the reaction.This process ultimately enhanced the catalyst’s activity.展开更多
Single-atom(SA) catalysts have emerged as a pivotal area drawing extensive research interest due to their high catalytic activities.However,SA catalysts are often plagued by the aggregation and deactivation of SA site...Single-atom(SA) catalysts have emerged as a pivotal area drawing extensive research interest due to their high catalytic activities.However,SA catalysts are often plagued by the aggregation and deactivation of SA sites under reaction conditions.This study focuses on CO oxidation over Gd-doped ceriasupported Cu catalysts and aims to provide a new strategy to stabilize the SA site,in which a Cu SA site is "prestored" in a relatively stable Cu cluster and can be dynamically activated under reaction conditions.Three typical Cu_(10)/CeO_(2)catalyst models were built with different Gd-doping contents,which are pristine Cu_(10)/CeO_(2),Cu_(10)/Gd_(0.125)Ce_(0.875)O_(2),and Cu_(10)/Gd_(0.25)Ce_(0.75)O_(2),respectively.We performed density functional theory(DFT) calculations on the Cu_(10)/Gd-CeO_(2)system to investigate the adsorption of CO and O_(2)molecules,the formation of surface oxygen vacancy(OV) and dynamic Cu SA site,and potential energy surfaces of CO oxidation process.Ab initio thermodynamic analysis suggests that the saturation adsorption of CO on Cu_(10)and high Gd-doping in CeO_(2)lead to a spontaneously formed single Cu-CO site and an OVdefect on ceria surface.The CO oxidation process is identified as a two-paths-coupled catalytic cycle,in which Path Ⅰ is activated by the terminal O atom of adsorbed O_(2)at surface OVsite while Path Ⅱinitiates with the lattice O atom of CeO_(2)surface.The micro kinetic modeling demonstrates that the dominant pathway is Path Ⅰ for the undoped and low-doping cases,and Path Ⅱ for the high-doping case which exhibits a novel mechanism for CO oxidation and the highest reaction activity due to the participation of the dynamic SA site.展开更多
A series of heteronuclear yttrium-nickel monoxide carbonyl complexes YNiO(CO)_(n)^(-)(n=1-5)were generated in a pulsed-laser vaporization source and characterized by mass-selected photoelectron velocity-map spectrosco...A series of heteronuclear yttrium-nickel monoxide carbonyl complexes YNiO(CO)_(n)^(-)(n=1-5)were generated in a pulsed-laser vaporization source and characterized by mass-selected photoelectron velocity-map spectroscopy combined with theoretical calculations.CO ligand-mediated reactivity in CO oxidation of yttrium-nickel monoxide carbonyl complexes was experimentally and theoretically identified.During the consecutive CO adsorption,aμ^(2)-O linear structure was most favorable for YNiO(CO)_(n)^(-)(n=1,2),then a structure in which the terminal O was bonded to the Y atom became favored for YNiO(CO)_(3)^(-),and finally a structure bearing a CO_(2)moiety was most favorable for YNiO(CO)_(n)^(-)(n=4,5).Theoretical calculations indicated that the Ni atom acted as an electron acceptor and accumulated electron density at n≤3,and then served as an electron donor along with the Y atom to contribute electron density in the rearrangement that accompanied CO oxidation at n>3.展开更多
The development of efficient low-load platinum catalysts for CO oxidation is critical for large-scale industrial applications and environmental protection.In this study,a strategy of N_(2)treatment triggered the self-...The development of efficient low-load platinum catalysts for CO oxidation is critical for large-scale industrial applications and environmental protection.In this study,a strategy of N_(2)treatment triggered the self-reforming into fully exposed Pt cluster catalysts was proposed.By adjusting the coordination environment of Pt species on the defect support through N_(2)treatment,the CO catalytic activity was significantly enhanced,achieving complete CO oxidation at 130℃with a Pt loading of only 0.1 wt.%.The turnover frequency of N_(2)-treated Pt_(FEC)/Ti-D at 160℃was 18.3 times that of untreated Pt_(SA)/Ti-D.Comprehensive characterization results indicated that the N_(2)treatment of the Pt single-atom defect catalyst facilitated the reconfiguration and evolution of the defect structure,leading to the aggregation of Pt single atoms into fully exposed Pt clusters.Notably,these fully exposed Pt clusters exhibited a reduced coordination of Pt–O in the first coordination shell compared to single atoms,which resulted in the formation of Pt–Pt metal coordination.This unique coordination structure enhanced the adsorption and activation of CO and O_(2)on the catalyst,thereby resulting in exceptionally low-temperature CO oxidation activity.This work demonstrates a promising strategy for the design,synthesis,and industrial application of efficient low-platinum load catalysts.展开更多
A series of Au/Co_(x)Fe_(3-x)O_(4) catalysts was synthesized using the sol-deposition method by depositing 2–5 nm Au particles on Fe-doped Co_(3)O_(4).Co_(2)FeO_(4),with a Co/Fe molar ratio of 2:1,exhibited higher sp...A series of Au/Co_(x)Fe_(3-x)O_(4) catalysts was synthesized using the sol-deposition method by depositing 2–5 nm Au particles on Fe-doped Co_(3)O_(4).Co_(2)FeO_(4),with a Co/Fe molar ratio of 2:1,exhibited higher specific surface area,Co^(3+)/Co^(2+)ratio,and oxygen vacancy content compared to Co_(3)O_(4).As a result,it displayed better performance in CO oxidation,achieving a total conversion temperature(T100)of 96℃.Au greatly improved the catalytic efficiency of all Co_(x)Fe_(3-x)O_(4) samples,with the 0.2%Au/Co_(2)FeO_(4) catalyst achieving a further decrease in T100 to 73℃.Stability tests conducted at room temperature on the 1%Au/Co_(x)Fe_(3-x)O_(4) catalysts demonstrated a slowed deactivation rate after Fe-doping.The reaction pathway for CO oxidation catalyzed by Au/Co_(2)FeO_(4) followed the Mars-van Krevelen mechanism.展开更多
The catalyst cost is a key factor limiting the CO purification of sintering flue gas.Here,an ultra-low-loading high-entropy catalyst was prepared by simple calcination process.By anchoring multiple active metal sites ...The catalyst cost is a key factor limiting the CO purification of sintering flue gas.Here,an ultra-low-loading high-entropy catalyst was prepared by simple calcination process.By anchoring multiple active metal sites in the stable anatase TiO_(2)phase,it shows efficient CO catalytic oxidation activity.The metal components(Pt,Mn,Fe,Co,Ni)were uniformly dispersed on the surface of TiO_(2)in the form of high-entropy compounds and undergo strong metal and support interaction with TiO_(2).The results showed that 0.1(PtMnFeCoNi)/TiO_(2)achieved complete oxidation of CO at 230℃,and its catalytic oxidation ability was significantly better than that of the corresponding monometallic and bimetallic catalysts.The high-entropy component adjusts the electronic environment between the TiO_(2)support and the metal to promote the reduction of the Ti_(3d)band gap,enhances the electron-induced ability of the catalytic system to gas molecules(CO and O_(2)),and exhibits excellent resistance to SO_(2)and H_(2)O.The work is of great significance to understand the synergistic regulation of catalyst activity by multiple metal at the atomic level and provides a strategy for effectively reducing the content of precious metals in the catalyst.展开更多
The expandable graphite(EG)modified TiO_(2) nanocomposites were prepared by the high shearmethod using the TiO_(2) nanoparticles(NPs)and EG as precursors,in which the amount of EG doped in TiO_(2) was 10 wt.%.Followed...The expandable graphite(EG)modified TiO_(2) nanocomposites were prepared by the high shearmethod using the TiO_(2) nanoparticles(NPs)and EG as precursors,in which the amount of EG doped in TiO_(2) was 10 wt.%.Followed by the impregnation method,adjusting the pH of the solution to 10,and using the electrostatic adsorption to achieve spatial confinement,the Pt elementswere mainly distributed on the exposed TiO_(2),thus generating the Pt/10EG-TiO_(2)-10 catalyst.The best CO oxidation activity with the excellent resistance to H_(2)O and SO_(2) was obtained over the Pt/10EG-TiO_(2)-10 catalyst:CO conversion after 36 hr of the reaction was ca.85%under the harsh condition of 10 vol.%H_(2)O and 100 ppm SO_(2) at a high gaseous hourly space velocity(GHSV)of 400,000 hr−1.Physicochemical properties of the catalystswere characterized by various techniques.The results showed that the electrostatic adsorption,which riveted the Pt elements mainly on the exposed TiO_(2) of the support surface,reduced the dispersion of Pt NPs on EG and achieved the effective dispersion of Pt NPs,hence significantly improving CO oxidation activity over the Pt/10EG-TiO_(2)-10 catalyst.The 10 wt.%EG doped in TiO_(2) caused the TiO_(2) support to form a more hydrophobic surface,which reduced the adsorption of H_(2)O and SO_(2) on the catalyst,greatly inhibited deposition of the TiOSO_(4) and formation of the PtSO4 species as well as suppressed the oxidation of SO_(2),thus resulting in an improvement in the resistance to H_(2)O and SO_(2) of the Pt/10EG-TiO_(2)-10 catalyst.展开更多
Intercalation of rare-earth(RE)into Pt offers an option to optimize the electronic structure of Pt-based catalysts by interaction effect,in which the synergistic catalytic sites are of great significance,yet the under...Intercalation of rare-earth(RE)into Pt offers an option to optimize the electronic structure of Pt-based catalysts by interaction effect,in which the synergistic catalytic sites are of great significance,yet the underpinning mechanism remains elusive.Herein,the introduction of silanol nests enables the alloy formation on the SiO_(2)surface.The amination modification is disclosed to induce the electron transfer from RE to Pt and weaken the adsorption of CO on electron-rich Pt species.In situ/operando spectroscopic analyses in conjunction with density functional theory calculations demonstrate the electronic couple of Pt atoms and adjacent Ce atoms concurrently achieves the enhancement of CO oxidation and suppression of H_(2)oxidation.Additionally,CO_(2)is readily desorbed from the Pt_(5)Ce(111)surface to enhance intrinsic activity and longevity.These findings provide an atomic-level insight into the synergistic catalytic sites on regulating the electronic state of the Pt-RE alloy catalysts toward highly selective oxidation reactions.展开更多
In this work,several ceria-zirconia based catalysts with very lo w(and equimolar) metal contents were prepared,characterised and tested for the CO oxidatio n reaction(under lean and stoichiometric conditions),trying t...In this work,several ceria-zirconia based catalysts with very lo w(and equimolar) metal contents were prepared,characterised and tested for the CO oxidatio n reaction(under lean and stoichiometric conditions),trying to emulate those conditions found in a diesel oxidation catalyst(DOC) system from a diesel engine and those encountered under gasoline exhaust(λ=1).The metals chosen are Cu,Co,Ag and Pt(as a reliable benchmark).The results reveal enormous differences among reducibility and catalytic activity despite quite similar structural and textural properties of the catalysts,showing differences among dispersion(Ag-catalyst seems to present a low level of dispersion).This catalyst seems to be characterised,as well,by a strong electronic interaction between Ce and Ag centres which is suggested to yield an improved reducibility under H_(2)-TPR conditions.Nevertheless,the order in catalytic activity(Cu>Ag>Co≈Pt>>support) seems not to follow the order found in reducibility and the Cu-catalyst seems to be the most active independently on the reaction conditions,yielding nearly overlapped CO oxidation catalytic curves.Inte restingly,a stro ng correlation between the catalytic activity under the two conditions tested and the OSC values of the Ce_(0.8)Zr_(0.2)O_(2)-supported metal catalysts is found.Therefore,OSC parameter measured at 150℃ can be used as a relevant descriptor to evaluate the CO oxidation activity at low and medium conversions for the investigated catalysts,much better than the H_(2)-TPR measurements.展开更多
The surface properties of oxidic supports and their interaction with the supported metals play critical roles in governing the catalytic activities of oxide‐supported metal catalysts.When metals are supported on redu...The surface properties of oxidic supports and their interaction with the supported metals play critical roles in governing the catalytic activities of oxide‐supported metal catalysts.When metals are supported on reducible oxides,dynamic surface reconstruction phenomena,including strong metal–support interaction(SMSI)and oxygen vacancy formation,complicate the determination of the structural–functional relationship at the active sites.Here,we performed a systematic investigation of the dynamic behavior of Au nanocatalysts supported on flame‐synthesized TiO_(2),which takes predominantly a rutile phase,using CO oxidation above room temperature as a probe reaction.Our analysis conclusively elucidated a negative correlation between the catalytic activity of Au/TiO_(2) and the oxygen vacancy at the Au/TiO_(2) interface.Although the reversible formation and retracting of SMSI overlayers have been ubiquitously observed on Au/TiO_(2) samples,the catalytic consequence of SMSI remains inconclusive.Density functional theory suggests that the electron transfer from TiO_(2) to Au is correlated to the presence of the interfacial oxygen vacancies,retarding the catalytic activation of CO oxidation.展开更多
The interaction between support and noble metal plays a crucial role in heterogeneous catalysis design.However,how to tune metal support interactions to optimize the activity still needs further exploration.CeO_(2) wa...The interaction between support and noble metal plays a crucial role in heterogeneous catalysis design.However,how to tune metal support interactions to optimize the activity still needs further exploration.CeO_(2) was introduced to promote CO oxidation ove r Ir/TiO_(2) by adjusting the interaction strength between iridium(Ir)and CeO_(2).The strong interaction between Ir and CeO_(2) blocks CO adsorption and causes low CO oxidation activity.However,introducing CeO_(2) on Ir/TiO_(2) produces localized interaction between Ir and CeO_(2),which can tune the surface electronic state of Ir,so a"volcano curve"relationship between CO oxidation activity and electronic state is built.Limited amount of CeO_(2) on Ir/TiO_(2)(Ir/Ce_(0.2)Ti)leads to CO complete oxidization at 22℃,and a new pathway for CO oxidation was explored.The study demonstrates that the utilization of tuning interaction strength between active metal and support is a potential method to increase the catalytic activity.展开更多
Several ternary oxides CuCeZrO_(y)(CCZ)were synthesized by a facile grinding method followed by calcination at high temperatures,and used as catalysts for CO oxidation at low temperatures.The influences of calcination...Several ternary oxides CuCeZrO_(y)(CCZ)were synthesized by a facile grinding method followed by calcination at high temperatures,and used as catalysts for CO oxidation at low temperatures.The influences of calcination temperature(400-600℃)on the physicochemical properties of the assynthesized ternary oxides were investigated by thermogravimetric analysis/differential scanning calorimetry(TGA/DSC),X-ray diffraction(XRD),transmission electron microscopy(TEM),Raman,inductively coupled plasma-optical emission spectrometry(ICP-OES),N_(2) adsorption,H_(2)-temperature programmed reduction(H_(2)-TPR),and X-ray photoelectron spectroscopy(XPS)characterizations.The results show that the increase in calcination temperature from 400 to 500℃is conducive to the high dispersion of CuOx on catalyst surface and the incorporation of Cu species into the support to form the Cu-Ce-Zr-O solid solution.Further raising of calcination temperature from 500 to 600℃,however,leads to the segregation of Cu species from the solid solution to aggregate on support surface and growth of highly dispersed CuOx nanoparticles.The highest catalytic activity is acquired over the CCZ calcined at 500℃,which can be ascribed to the largest contents of Cu+species and oxygen vacancies owing to the formation of the maximum amount of Cu-Ce-Zr-O solid solution.展开更多
Low‐temperature CO oxidation is important for both fundamental studies and practical applica‐tions. Supported gold catalysts are generally regarded as the most active catalysts for low‐temperature CO oxidation. The...Low‐temperature CO oxidation is important for both fundamental studies and practical applica‐tions. Supported gold catalysts are generally regarded as the most active catalysts for low‐temperature CO oxidation. The active sites are traditionally believed to be Au nanoclusters or nanoparticles in the size range of 0.5–5 nm. Only in the last few years have single‐atom Au catalysts been proved to be active for CO oxidation. Recent advances in both experimental and theoretical studies on single‐atom Au catalysts unambiguously demonstrated that when dispersed on suitable oxide supports the Au single atoms can be extremely active for CO oxidation. In this mini‐review, recent advances in the development of Au single‐atom catalysts are discussed, with the aim of illus‐trating their unique catalytic features during CO oxidation.展开更多
Leached Pt-Fe and Pt-Co catalysts were prepared by acid leaching the reduced catalysts in acid solution. Oxidation treatments of leached catalysts produced the structure o f metal oxides decorat-ing the surface of...Leached Pt-Fe and Pt-Co catalysts were prepared by acid leaching the reduced catalysts in acid solution. Oxidation treatments of leached catalysts produced the structure o f metal oxides decorat-ing the surface of nanoparticles. The fully oxidized Fe2O3 and Co3O4 species on Pt nanoparticle sur-faces result in the low performance of the CO complete oxidation （COOX） reaction. In contrast, un-saturated FeO and CoO surface species can be formed during exposure to the CO preferential oxida-tion （CO-PROX） reaction with an excess of H2, leading to a high O2 activation ability and enhancing the CO-PROX activity. The FeOx surface structures can be transformed between these two states by varying the reactive gas environments, exhibiting oscillating activity in these two reactions. Con-versely, the CoO surface structure formed in the H2 -rich atmosphere is stable when exposed to the COOX reaction and exhibits similar activity in these two reactions. It is hoped that this work may assist in understanding the important role of surface oxides in real reactions.展开更多
The influence of Ce doping and the precipitation method on structural properties and the catalytic activity of copper manganese oxides for CO oxidation at ambient temperature have been investigated. The catalysts were...The influence of Ce doping and the precipitation method on structural properties and the catalytic activity of copper manganese oxides for CO oxidation at ambient temperature have been investigated. The catalysts were characterized by means of the powder X-ray diffraction and N2 adsorption-desorption, the inductively coupled plasma atomic emission spectrometry, the temperature programmed reduction, diffuse reflectance UV-Vis spectra, and the X-ray photoelectron spectroscopy. It was found that after doping little amount of Ce in copper manganese oxide, CeO2 phase was highly dispersed and could prevent sintering and aggregating of the catalyst, the size of the catalytic material was decreased, the reducibility was enhanced, the specific surface area was increased and the formation of the active sites for the oxidation of CO was improved significantly. Therefore, the activity of the rare earth promoted catalyst was enhanced remarkably.展开更多
Co3O4/SiO2 catalysts for CO oxidation were prepared by conventional incipient wetness impregnation followed by calcination at various temperatures. Their structures were char- acterized with X-ray diffraction （XRD）,...Co3O4/SiO2 catalysts for CO oxidation were prepared by conventional incipient wetness impregnation followed by calcination at various temperatures. Their structures were char- acterized with X-ray diffraction （XRD）, laser Raman spectroscopy, X-ray photoelectron spectroscopy （XPS）, temperature-programmed reduction （TPR） and X-ray absorption fine structure （XAFS） spectroscopy. Both XRD and Raman spectroscopy only detect the existence of Co3O4 crystallites in all catalysts. However, XPS results indicate that excess Co2＋ ions are present on the surface of Co3O4 in Co3O4（200）/Si02 as compared with bulk Co3O4. Meanwhile, TPR results suggest the presence of surface oxygen vacancies on Co3O4 in Co3O4（200）/SiO2, and XAFS results demonstrate that Co3O4 in Co3O4（200）/SIO2 contains excess Co2＋. Increasing calcination temperature results in oxidation of excess Co2＋ and the decrease of the concentration of surface oxygen vacancies, consequently the for- mation of stoichiometric Co3O4 on supported catalysts. Among all Co3O4/SiO2 catalysts, Co3O4（200）/SiO2 exhibits the best catalytic performance towards CO oxidation, demonstrating that excess Co2＋ and surface oxygen vacancies can enhance the catalytic activity of Co3O4 towards CO oxidation. These results nicely demonstrate the effect of calcination temperature on the structure and catalytic performance towards CO oxidation of silicasupported Co3O4 catalysts and highlight the important role of surface oxygen vacancies on Co3O4.展开更多
A series of K-promoted Pt/Al2O3 catalysts were tested for CO oxidation. It was found that the addition of K significantly enhanced the activity. A detailed kinetic study showed that the activation energies of the K-co...A series of K-promoted Pt/Al2O3 catalysts were tested for CO oxidation. It was found that the addition of K significantly enhanced the activity. A detailed kinetic study showed that the activation energies of the K-containing catalysts were lower than those of the K-free ones, particularly for catalysts with high Pt contents （51.6 k）/mol for 0.42K-2.0Pt/Al2O3 and 6：3.6 kJ/mol for 2.0Pt/Al2O3 ）. The CO reaction orders were higher for the K-containing catalysts （about -0.2） than for the K-free ones （about -0.5）, with the former having much lower equilibrium constants for CO adsorption than the latter. In situ Fourier-transform infrared spectroscopy showed that surface CO desorption from the 0.42K-2.0Pt/Al2O3 catalyst was easier than from 2.0Pt/Al2O3. The promoting effect of K was therefore caused by weakening of the interactions between CO and surface Pt atoms. This decreased coverage of the catalyst with CO and facilitated competitive O2 chemisorption on the Pt surface, and significantly lowered the reaction barrier between chemisorbed CO and O2 species.展开更多
A modified CuO/CeO2 catalyst was prepared by surfactant-assisted impregnation method and showed better catalytic activity for low temperature CO oxidation than that from conventional impregnation method. The physicoch...A modified CuO/CeO2 catalyst was prepared by surfactant-assisted impregnation method and showed better catalytic activity for low temperature CO oxidation than that from conventional impregnation method. The physicochemical properties of different CuO/CeO2 catalysts were characterized by thermogravimetrie and differential scanning calorimetric measurements （TG-DSC）, X-ray diffraction （XRD）, N2 adsorpti0n-desorption, Raman spectroscopy, H2 temperature-programmed reduction （H2-TPR）, tern- perature-programmed desorption of 02 （O2-TPD）, and diffuse reflectance infrared Fourier transform spectroscopy （DRIFTS）. The re- sults suggested that the addition of hexadecyl trimethyl ammonium bromide （CTAB） into the impregnation solution could improve the dispersion of CuO species, which could facilitate Cu2＋ incorporating into CeO2 lattice and strengthened the synergistic effects between CuO and CeO2, making the lattice oxygen more active, and eventually resulting in enhanced activity for CO oxidation.展开更多
A urea-nitrate combustion method was used to prepare Ce-Mn-O material, which was applied as the support for a series of CuO/Ce-Mn-O catalysts. The structure of the catalysts was characterized with Nz adsorption/desorp...A urea-nitrate combustion method was used to prepare Ce-Mn-O material, which was applied as the support for a series of CuO/Ce-Mn-O catalysts. The structure of the catalysts was characterized with Nz adsorption/desorption, X-ray diffraction （XRD）, temperature-programmed reduction （TPR） and X-ray photoelectron spectroscopy （XPS）. The catalytic activity of the catalysts for the oxidation of CO was evaluated on a conventional fixed-bed quartz reactor. XRD results showed that the synergetic effect between manganese and cerium led to a little higher electron density of Ce3＋ in the mixed oxides. When the CuO content was lower than 5 wt.%, Cu species were well dispersed onto the Ce-Mn-O support or/and they formed a solid solution with CeO2 （inside the fluorite lattice）. At higher CuO content （CuO〉5 wt.%）, large CuO particles were observed. There was strong interaction among ceria, man- ganese and copper oxide because of the doping of Mn. This interplay changed the reducibility and the valence states of the compo- nents, leading to the improved activity of the CuO/Ce-Mn-O catalysts.展开更多
基金Project supported by the National Natural Science Foundation of China(52206180)。
文摘In this work,the surface properties of CeO_(2)-supported Cu catalysts were adjusted via doping Mn or/and Co with different ratios(CuMnaCO_(1-a)/Ce,a=0,0.25,0.5,0.75 and 1).The roles of metallic effects on the activities,structures and reaction pathways of the catalysts were investigated using various characterization techniques.The results reveal the CuMnCo/Ce catalysts show better performance,followed by Cu/Ce and MnCo/Ce.Among CuMnCo/Ce catalysts,the CuMn_(0.25)Co_(0.75)/Ce exhibits the excellent activity under a higher gas hourly space velocity.The improved surface properties mainly involve the higher dispersion of CuOxand stronger redox cycle due to Co substitution,and more active oxygen species(oxygen vacancies and activated lattice oxygen)contributed by Mn substitution.From the in situ infrared spectroscopy(in situ IR)experiments,the electron transfer of Cu and Co can strengthen the adsorption of CO on Cu species indirectly,whereas,more oxygen defects coming from the Mn-OV-Ce structure boost the activation of oxygen species,the formation of carbonate intermediates and then the release of CO_(2).This work may guide the simple regulation of active sites and the utilization of the catalytic potential of Cu-Ce oxide catalysts.
基金supported by the National Key R&D Program of China(No.2022YFB3805504)the National Natu-ral Science Foundation of China(No.22078089)+2 种基金the Shanghai Pilot Program for Basic Research(No.22TQ1400100-7)the Basic Research Program of Science and Technology Commission of Shanghai Munici-pality(No.22JC1400600)the Fundamental Research Funds for the Central Universities.
文摘Carbon monoxide(CO)oxidation is crucial for pollutant removal and hydrogen purification.In recent years,copper–cerium(Cu–Ce)-mixed oxide catalysts have attracted significant attention due to their excellent activity and stability in CO oxida-tion.This study presents an innovative,environmentally friendly electrosynthesis method for producing stable,structured Cu–Ce catalysts in mesh form.This approach addresses the limitations of traditional pellet catalysts,such as fragility and poor thermal conductivity.The results demonstrated that incorporating cerium(Ce)enhanced the catalytic activity for CO oxidation threefold.A series of in situ characterizations revealed that the introduction of Ce led to the formation of a Cu–Ce mixed oxide solid solution,which significantly improved catalytic performance.Furthermore,higher pretreatment tem-peratures facilitated the decomposition of Ce compounds(nitrate and hydroxide),which promotes the formation of Cu–Ce solid solutions and increases the concentration of active intermediate species(Cu^(+)-CO)during the reaction.This process ultimately enhanced the catalyst’s activity.
基金Project supported by State Key Laboratory of Molecular&Process Engineering (RIPP, SINOPEC)(36800000-23-ZC0699-0042)the National Natural Science Foundation of China (22072182, 21776315, 12104513)+2 种基金the National Key Research and Development Program of China (2019YFA0708703)the Taishan Scholars Program of Shandong Province (tsqn201909071)the Shandong Provincial Natural Science Foundation of China (ZR2020QA050, ZR2023MB034)。
文摘Single-atom(SA) catalysts have emerged as a pivotal area drawing extensive research interest due to their high catalytic activities.However,SA catalysts are often plagued by the aggregation and deactivation of SA sites under reaction conditions.This study focuses on CO oxidation over Gd-doped ceriasupported Cu catalysts and aims to provide a new strategy to stabilize the SA site,in which a Cu SA site is "prestored" in a relatively stable Cu cluster and can be dynamically activated under reaction conditions.Three typical Cu_(10)/CeO_(2)catalyst models were built with different Gd-doping contents,which are pristine Cu_(10)/CeO_(2),Cu_(10)/Gd_(0.125)Ce_(0.875)O_(2),and Cu_(10)/Gd_(0.25)Ce_(0.75)O_(2),respectively.We performed density functional theory(DFT) calculations on the Cu_(10)/Gd-CeO_(2)system to investigate the adsorption of CO and O_(2)molecules,the formation of surface oxygen vacancy(OV) and dynamic Cu SA site,and potential energy surfaces of CO oxidation process.Ab initio thermodynamic analysis suggests that the saturation adsorption of CO on Cu_(10)and high Gd-doping in CeO_(2)lead to a spontaneously formed single Cu-CO site and an OVdefect on ceria surface.The CO oxidation process is identified as a two-paths-coupled catalytic cycle,in which Path Ⅰ is activated by the terminal O atom of adsorbed O_(2)at surface OVsite while Path Ⅱinitiates with the lattice O atom of CeO_(2)surface.The micro kinetic modeling demonstrates that the dominant pathway is Path Ⅰ for the undoped and low-doping cases,and Path Ⅱ for the high-doping case which exhibits a novel mechanism for CO oxidation and the highest reaction activity due to the participation of the dynamic SA site.
基金supported by the Natural Science Foundation of Shandong Province(No.ZR2021QB215)the National Natural Science Foundation of China(Nos.22273101,22125303,92061203,21327901,and 22288201)+2 种基金Dalian Institute of Chemical Physics(No.DICP I202437)the Talent Induction Program for Youth Innovation Teams in Colleges and Universities of Shandong Province(No.2022-2024)the Talent Introduction Research Start-up Funds of Ludong University(No.20212026)。
文摘A series of heteronuclear yttrium-nickel monoxide carbonyl complexes YNiO(CO)_(n)^(-)(n=1-5)were generated in a pulsed-laser vaporization source and characterized by mass-selected photoelectron velocity-map spectroscopy combined with theoretical calculations.CO ligand-mediated reactivity in CO oxidation of yttrium-nickel monoxide carbonyl complexes was experimentally and theoretically identified.During the consecutive CO adsorption,aμ^(2)-O linear structure was most favorable for YNiO(CO)_(n)^(-)(n=1,2),then a structure in which the terminal O was bonded to the Y atom became favored for YNiO(CO)_(3)^(-),and finally a structure bearing a CO_(2)moiety was most favorable for YNiO(CO)_(n)^(-)(n=4,5).Theoretical calculations indicated that the Ni atom acted as an electron acceptor and accumulated electron density at n≤3,and then served as an electron donor along with the Y atom to contribute electron density in the rearrangement that accompanied CO oxidation at n>3.
基金supported by the National Natural Science Foundation of China(52170118,52322004,52230002)the China Postdoctoral Science Foundation(2024M763296).
文摘The development of efficient low-load platinum catalysts for CO oxidation is critical for large-scale industrial applications and environmental protection.In this study,a strategy of N_(2)treatment triggered the self-reforming into fully exposed Pt cluster catalysts was proposed.By adjusting the coordination environment of Pt species on the defect support through N_(2)treatment,the CO catalytic activity was significantly enhanced,achieving complete CO oxidation at 130℃with a Pt loading of only 0.1 wt.%.The turnover frequency of N_(2)-treated Pt_(FEC)/Ti-D at 160℃was 18.3 times that of untreated Pt_(SA)/Ti-D.Comprehensive characterization results indicated that the N_(2)treatment of the Pt single-atom defect catalyst facilitated the reconfiguration and evolution of the defect structure,leading to the aggregation of Pt single atoms into fully exposed Pt clusters.Notably,these fully exposed Pt clusters exhibited a reduced coordination of Pt–O in the first coordination shell compared to single atoms,which resulted in the formation of Pt–Pt metal coordination.This unique coordination structure enhanced the adsorption and activation of CO and O_(2)on the catalyst,thereby resulting in exceptionally low-temperature CO oxidation activity.This work demonstrates a promising strategy for the design,synthesis,and industrial application of efficient low-platinum load catalysts.
基金supported by the Fundamental Research Program of Shanxi Province of China(202203021211103,202303021212172,202403021211196).
文摘A series of Au/Co_(x)Fe_(3-x)O_(4) catalysts was synthesized using the sol-deposition method by depositing 2–5 nm Au particles on Fe-doped Co_(3)O_(4).Co_(2)FeO_(4),with a Co/Fe molar ratio of 2:1,exhibited higher specific surface area,Co^(3+)/Co^(2+)ratio,and oxygen vacancy content compared to Co_(3)O_(4).As a result,it displayed better performance in CO oxidation,achieving a total conversion temperature(T100)of 96℃.Au greatly improved the catalytic efficiency of all Co_(x)Fe_(3-x)O_(4) samples,with the 0.2%Au/Co_(2)FeO_(4) catalyst achieving a further decrease in T100 to 73℃.Stability tests conducted at room temperature on the 1%Au/Co_(x)Fe_(3-x)O_(4) catalysts demonstrated a slowed deactivation rate after Fe-doping.The reaction pathway for CO oxidation catalyzed by Au/Co_(2)FeO_(4) followed the Mars-van Krevelen mechanism.
文摘The catalyst cost is a key factor limiting the CO purification of sintering flue gas.Here,an ultra-low-loading high-entropy catalyst was prepared by simple calcination process.By anchoring multiple active metal sites in the stable anatase TiO_(2)phase,it shows efficient CO catalytic oxidation activity.The metal components(Pt,Mn,Fe,Co,Ni)were uniformly dispersed on the surface of TiO_(2)in the form of high-entropy compounds and undergo strong metal and support interaction with TiO_(2).The results showed that 0.1(PtMnFeCoNi)/TiO_(2)achieved complete oxidation of CO at 230℃,and its catalytic oxidation ability was significantly better than that of the corresponding monometallic and bimetallic catalysts.The high-entropy component adjusts the electronic environment between the TiO_(2)support and the metal to promote the reduction of the Ti_(3d)band gap,enhances the electron-induced ability of the catalytic system to gas molecules(CO and O_(2)),and exhibits excellent resistance to SO_(2)and H_(2)O.The work is of great significance to understand the synergistic regulation of catalyst activity by multiple metal at the atomic level and provides a strategy for effectively reducing the content of precious metals in the catalyst.
基金supported by the National Key R&D Program of China (No.2017YFC0210303).
文摘The expandable graphite(EG)modified TiO_(2) nanocomposites were prepared by the high shearmethod using the TiO_(2) nanoparticles(NPs)and EG as precursors,in which the amount of EG doped in TiO_(2) was 10 wt.%.Followed by the impregnation method,adjusting the pH of the solution to 10,and using the electrostatic adsorption to achieve spatial confinement,the Pt elementswere mainly distributed on the exposed TiO_(2),thus generating the Pt/10EG-TiO_(2)-10 catalyst.The best CO oxidation activity with the excellent resistance to H_(2)O and SO_(2) was obtained over the Pt/10EG-TiO_(2)-10 catalyst:CO conversion after 36 hr of the reaction was ca.85%under the harsh condition of 10 vol.%H_(2)O and 100 ppm SO_(2) at a high gaseous hourly space velocity(GHSV)of 400,000 hr−1.Physicochemical properties of the catalystswere characterized by various techniques.The results showed that the electrostatic adsorption,which riveted the Pt elements mainly on the exposed TiO_(2) of the support surface,reduced the dispersion of Pt NPs on EG and achieved the effective dispersion of Pt NPs,hence significantly improving CO oxidation activity over the Pt/10EG-TiO_(2)-10 catalyst.The 10 wt.%EG doped in TiO_(2) caused the TiO_(2) support to form a more hydrophobic surface,which reduced the adsorption of H_(2)O and SO_(2) on the catalyst,greatly inhibited deposition of the TiOSO_(4) and formation of the PtSO4 species as well as suppressed the oxidation of SO_(2),thus resulting in an improvement in the resistance to H_(2)O and SO_(2) of the Pt/10EG-TiO_(2)-10 catalyst.
基金financially supported by the National Natural Science Foundation of China(22468034)the Natural Science Foundation of Inner Mongolia(2021MS02008 and 2022MS02011)the Key Research and Development Project of Ordos(YF20240062)。
文摘Intercalation of rare-earth(RE)into Pt offers an option to optimize the electronic structure of Pt-based catalysts by interaction effect,in which the synergistic catalytic sites are of great significance,yet the underpinning mechanism remains elusive.Herein,the introduction of silanol nests enables the alloy formation on the SiO_(2)surface.The amination modification is disclosed to induce the electron transfer from RE to Pt and weaken the adsorption of CO on electron-rich Pt species.In situ/operando spectroscopic analyses in conjunction with density functional theory calculations demonstrate the electronic couple of Pt atoms and adjacent Ce atoms concurrently achieves the enhancement of CO oxidation and suppression of H_(2)oxidation.Additionally,CO_(2)is readily desorbed from the Pt_(5)Ce(111)surface to enhance intrinsic activity and longevity.These findings provide an atomic-level insight into the synergistic catalytic sites on regulating the electronic state of the Pt-RE alloy catalysts toward highly selective oxidation reactions.
基金Project supported by the Spanish Ministry of Science and Innovation/Research Spanish Agency (PID2019-105 542RB-100/AEI/10.13039/501100011033)the UE-FEDER funding and Generalitat Valenciana (CIPROM/2021/070)。
文摘In this work,several ceria-zirconia based catalysts with very lo w(and equimolar) metal contents were prepared,characterised and tested for the CO oxidatio n reaction(under lean and stoichiometric conditions),trying to emulate those conditions found in a diesel oxidation catalyst(DOC) system from a diesel engine and those encountered under gasoline exhaust(λ=1).The metals chosen are Cu,Co,Ag and Pt(as a reliable benchmark).The results reveal enormous differences among reducibility and catalytic activity despite quite similar structural and textural properties of the catalysts,showing differences among dispersion(Ag-catalyst seems to present a low level of dispersion).This catalyst seems to be characterised,as well,by a strong electronic interaction between Ce and Ag centres which is suggested to yield an improved reducibility under H_(2)-TPR conditions.Nevertheless,the order in catalytic activity(Cu>Ag>Co≈Pt>>support) seems not to follow the order found in reducibility and the Cu-catalyst seems to be the most active independently on the reaction conditions,yielding nearly overlapped CO oxidation catalytic curves.Inte restingly,a stro ng correlation between the catalytic activity under the two conditions tested and the OSC values of the Ce_(0.8)Zr_(0.2)O_(2)-supported metal catalysts is found.Therefore,OSC parameter measured at 150℃ can be used as a relevant descriptor to evaluate the CO oxidation activity at low and medium conversions for the investigated catalysts,much better than the H_(2)-TPR measurements.
基金Science and Technology Innovation Program of Hunan Province,Grant/Award Numbers:2020GK2070,2021RC4006Innovation‐Driven Project of Central South University,Grant/Award Number:2020CX008+3 种基金China Scholarship Council(CSC)National Key R&D Program of China,Grant/Award Number:2022YFE0105900National Natural Science Foundation of China,Grant/Award Number:52276093National Research Foundation Singapore,Grant/Award Number:CREATE。
文摘The surface properties of oxidic supports and their interaction with the supported metals play critical roles in governing the catalytic activities of oxide‐supported metal catalysts.When metals are supported on reducible oxides,dynamic surface reconstruction phenomena,including strong metal–support interaction(SMSI)and oxygen vacancy formation,complicate the determination of the structural–functional relationship at the active sites.Here,we performed a systematic investigation of the dynamic behavior of Au nanocatalysts supported on flame‐synthesized TiO_(2),which takes predominantly a rutile phase,using CO oxidation above room temperature as a probe reaction.Our analysis conclusively elucidated a negative correlation between the catalytic activity of Au/TiO_(2) and the oxygen vacancy at the Au/TiO_(2) interface.Although the reversible formation and retracting of SMSI overlayers have been ubiquitously observed on Au/TiO_(2) samples,the catalytic consequence of SMSI remains inconclusive.Density functional theory suggests that the electron transfer from TiO_(2) to Au is correlated to the presence of the interfacial oxygen vacancies,retarding the catalytic activation of CO oxidation.
基金Project supported by the Science Foundation of China Tobacco Zhejiang Industrial Co.LTD(ZJZY2021A013,ZJZY2023C001)the National Natural Science Foundation of China(21976057)。
文摘The interaction between support and noble metal plays a crucial role in heterogeneous catalysis design.However,how to tune metal support interactions to optimize the activity still needs further exploration.CeO_(2) was introduced to promote CO oxidation ove r Ir/TiO_(2) by adjusting the interaction strength between iridium(Ir)and CeO_(2).The strong interaction between Ir and CeO_(2) blocks CO adsorption and causes low CO oxidation activity.However,introducing CeO_(2) on Ir/TiO_(2) produces localized interaction between Ir and CeO_(2),which can tune the surface electronic state of Ir,so a"volcano curve"relationship between CO oxidation activity and electronic state is built.Limited amount of CeO_(2) on Ir/TiO_(2)(Ir/Ce_(0.2)Ti)leads to CO complete oxidization at 22℃,and a new pathway for CO oxidation was explored.The study demonstrates that the utilization of tuning interaction strength between active metal and support is a potential method to increase the catalytic activity.
基金Project supported by the National Natural Science Foundation of China(21273150)。
文摘Several ternary oxides CuCeZrO_(y)(CCZ)were synthesized by a facile grinding method followed by calcination at high temperatures,and used as catalysts for CO oxidation at low temperatures.The influences of calcination temperature(400-600℃)on the physicochemical properties of the assynthesized ternary oxides were investigated by thermogravimetric analysis/differential scanning calorimetry(TGA/DSC),X-ray diffraction(XRD),transmission electron microscopy(TEM),Raman,inductively coupled plasma-optical emission spectrometry(ICP-OES),N_(2) adsorption,H_(2)-temperature programmed reduction(H_(2)-TPR),and X-ray photoelectron spectroscopy(XPS)characterizations.The results show that the increase in calcination temperature from 400 to 500℃is conducive to the high dispersion of CuOx on catalyst surface and the incorporation of Cu species into the support to form the Cu-Ce-Zr-O solid solution.Further raising of calcination temperature from 500 to 600℃,however,leads to the segregation of Cu species from the solid solution to aggregate on support surface and growth of highly dispersed CuOx nanoparticles.The highest catalytic activity is acquired over the CCZ calcined at 500℃,which can be ascribed to the largest contents of Cu+species and oxygen vacancies owing to the formation of the maximum amount of Cu-Ce-Zr-O solid solution.
文摘Low‐temperature CO oxidation is important for both fundamental studies and practical applica‐tions. Supported gold catalysts are generally regarded as the most active catalysts for low‐temperature CO oxidation. The active sites are traditionally believed to be Au nanoclusters or nanoparticles in the size range of 0.5–5 nm. Only in the last few years have single‐atom Au catalysts been proved to be active for CO oxidation. Recent advances in both experimental and theoretical studies on single‐atom Au catalysts unambiguously demonstrated that when dispersed on suitable oxide supports the Au single atoms can be extremely active for CO oxidation. In this mini‐review, recent advances in the development of Au single‐atom catalysts are discussed, with the aim of illus‐trating their unique catalytic features during CO oxidation.
基金supported by the National Natural Science Foundation of China(21403004,21403003)~~
文摘Leached Pt-Fe and Pt-Co catalysts were prepared by acid leaching the reduced catalysts in acid solution. Oxidation treatments of leached catalysts produced the structure o f metal oxides decorat-ing the surface of nanoparticles. The fully oxidized Fe2O3 and Co3O4 species on Pt nanoparticle sur-faces result in the low performance of the CO complete oxidation （COOX） reaction. In contrast, un-saturated FeO and CoO surface species can be formed during exposure to the CO preferential oxida-tion （CO-PROX） reaction with an excess of H2, leading to a high O2 activation ability and enhancing the CO-PROX activity. The FeOx surface structures can be transformed between these two states by varying the reactive gas environments, exhibiting oscillating activity in these two reactions. Con-versely, the CoO surface structure formed in the H2 -rich atmosphere is stable when exposed to the COOX reaction and exhibits similar activity in these two reactions. It is hoped that this work may assist in understanding the important role of surface oxides in real reactions.
文摘The influence of Ce doping and the precipitation method on structural properties and the catalytic activity of copper manganese oxides for CO oxidation at ambient temperature have been investigated. The catalysts were characterized by means of the powder X-ray diffraction and N2 adsorption-desorption, the inductively coupled plasma atomic emission spectrometry, the temperature programmed reduction, diffuse reflectance UV-Vis spectra, and the X-ray photoelectron spectroscopy. It was found that after doping little amount of Ce in copper manganese oxide, CeO2 phase was highly dispersed and could prevent sintering and aggregating of the catalyst, the size of the catalytic material was decreased, the reducibility was enhanced, the specific surface area was increased and the formation of the active sites for the oxidation of CO was improved significantly. Therefore, the activity of the rare earth promoted catalyst was enhanced remarkably.
文摘Co3O4/SiO2 catalysts for CO oxidation were prepared by conventional incipient wetness impregnation followed by calcination at various temperatures. Their structures were char- acterized with X-ray diffraction （XRD）, laser Raman spectroscopy, X-ray photoelectron spectroscopy （XPS）, temperature-programmed reduction （TPR） and X-ray absorption fine structure （XAFS） spectroscopy. Both XRD and Raman spectroscopy only detect the existence of Co3O4 crystallites in all catalysts. However, XPS results indicate that excess Co2＋ ions are present on the surface of Co3O4 in Co3O4（200）/Si02 as compared with bulk Co3O4. Meanwhile, TPR results suggest the presence of surface oxygen vacancies on Co3O4 in Co3O4（200）/SiO2, and XAFS results demonstrate that Co3O4 in Co3O4（200）/SIO2 contains excess Co2＋. Increasing calcination temperature results in oxidation of excess Co2＋ and the decrease of the concentration of surface oxygen vacancies, consequently the for- mation of stoichiometric Co3O4 on supported catalysts. Among all Co3O4/SiO2 catalysts, Co3O4（200）/SiO2 exhibits the best catalytic performance towards CO oxidation, demonstrating that excess Co2＋ and surface oxygen vacancies can enhance the catalytic activity of Co3O4 towards CO oxidation. These results nicely demonstrate the effect of calcination temperature on the structure and catalytic performance towards CO oxidation of silicasupported Co3O4 catalysts and highlight the important role of surface oxygen vacancies on Co3O4.
基金financially supported by the National Natural Science Foundation of China(21173195)~~
文摘A series of K-promoted Pt/Al2O3 catalysts were tested for CO oxidation. It was found that the addition of K significantly enhanced the activity. A detailed kinetic study showed that the activation energies of the K-containing catalysts were lower than those of the K-free ones, particularly for catalysts with high Pt contents （51.6 k）/mol for 0.42K-2.0Pt/Al2O3 and 6：3.6 kJ/mol for 2.0Pt/Al2O3 ）. The CO reaction orders were higher for the K-containing catalysts （about -0.2） than for the K-free ones （about -0.5）, with the former having much lower equilibrium constants for CO adsorption than the latter. In situ Fourier-transform infrared spectroscopy showed that surface CO desorption from the 0.42K-2.0Pt/Al2O3 catalyst was easier than from 2.0Pt/Al2O3. The promoting effect of K was therefore caused by weakening of the interactions between CO and surface Pt atoms. This decreased coverage of the catalyst with CO and facilitated competitive O2 chemisorption on the Pt surface, and significantly lowered the reaction barrier between chemisorbed CO and O2 species.
基金supported by the National Natural Science Foundation of China(21273150)‘‘Shu Guang’’Project(10GG23)of Shanghai Municipal Education CommissionShanghai Education Development Foundation
文摘A modified CuO/CeO2 catalyst was prepared by surfactant-assisted impregnation method and showed better catalytic activity for low temperature CO oxidation than that from conventional impregnation method. The physicochemical properties of different CuO/CeO2 catalysts were characterized by thermogravimetrie and differential scanning calorimetric measurements （TG-DSC）, X-ray diffraction （XRD）, N2 adsorpti0n-desorption, Raman spectroscopy, H2 temperature-programmed reduction （H2-TPR）, tern- perature-programmed desorption of 02 （O2-TPD）, and diffuse reflectance infrared Fourier transform spectroscopy （DRIFTS）. The re- sults suggested that the addition of hexadecyl trimethyl ammonium bromide （CTAB） into the impregnation solution could improve the dispersion of CuO species, which could facilitate Cu2＋ incorporating into CeO2 lattice and strengthened the synergistic effects between CuO and CeO2, making the lattice oxygen more active, and eventually resulting in enhanced activity for CO oxidation.
基金supported by the National Natural Science Foundation of China(21303272)
文摘A urea-nitrate combustion method was used to prepare Ce-Mn-O material, which was applied as the support for a series of CuO/Ce-Mn-O catalysts. The structure of the catalysts was characterized with Nz adsorption/desorption, X-ray diffraction （XRD）, temperature-programmed reduction （TPR） and X-ray photoelectron spectroscopy （XPS）. The catalytic activity of the catalysts for the oxidation of CO was evaluated on a conventional fixed-bed quartz reactor. XRD results showed that the synergetic effect between manganese and cerium led to a little higher electron density of Ce3＋ in the mixed oxides. When the CuO content was lower than 5 wt.%, Cu species were well dispersed onto the Ce-Mn-O support or/and they formed a solid solution with CeO2 （inside the fluorite lattice）. At higher CuO content （CuO〉5 wt.%）, large CuO particles were observed. There was strong interaction among ceria, man- ganese and copper oxide because of the doping of Mn. This interplay changed the reducibility and the valence states of the compo- nents, leading to the improved activity of the CuO/Ce-Mn-O catalysts.
