Supported metal catalysts are the backbone of heterogeneous catalysis,playing a crucial role in the modern chemical industry.Metal-support interactions(MSIs)are known important in determining the catalytic performance...Supported metal catalysts are the backbone of heterogeneous catalysis,playing a crucial role in the modern chemical industry.Metal-support interactions(MSIs)are known important in determining the catalytic performance of supported metal catalysts.This is particularly true for single-atom catalysts(SACs)and pseudo-single-atom catalysts(pseudo-SACs),where all metal atoms are dispersed on,and interact directly with the support.Consequently,the MSI of SACs and pseudo-SACs are theoretically more sensitive to modulation compared to that of traditional nanoparticle catalysts.In this work,we experimentally demonstrated this hypothesis by an observed size-dependent MSI modulation.We fabricated CoFe_(2)O_(4) supported Pt pseudo-SACs and nanoparticle catalysts,followed by a straightforward water treatment process.It was found that the covalent strong metal-support interaction(CMSI)in pseudo-SACs can be weakened,leading to a significant activity improvement in methane combustion reaction.This finding aligns with our recent observation of CoFe_(2)O_(4) supported Pt SACs.By contrast,the MSI in Pt nanoparticle catalyst was barely affected by the water treatment,giving rise to almost unchanged catalytic performance.This work highlights the critical role of metal size in determining the MSI modulation,offering a novel strategy for tuning the catalytic performance of SACs and pseudo-SACs by fine-tuning their MSIs.展开更多
Catalytic oxidation is an effective strategy for eliminating CO pollutant.Pt/TiO_(2) catalyst are one of the most active catalysts as used,but facing the issue of sulfur and water deactivation.In this study,TiO_(2) wa...Catalytic oxidation is an effective strategy for eliminating CO pollutant.Pt/TiO_(2) catalyst are one of the most active catalysts as used,but facing the issue of sulfur and water deactivation.In this study,TiO_(2) was synthesized using a sol-gel method,while Pt/TiO_(2) was prepared by impregnation method.By varying the calcination temperature of the TiO_(2) support,Pt/TiO_(2) catalysts with different proportions of anatase and rutile phases were synthesized.At the calcination temperature of 500℃,the catalysts exhibited approximately equal proportions of anatase and rutile,resulting in exceptional catalytic activity for CO oxidation,as well as improved resistance to sulfur and water in the flue gas.Consequently,the Pt/TiO_(2)-500 catalyst achieved a CO conversion of 93%at 160℃.Even under conditions of 8%(vol)H_(2)O and 0.016%(vol)SO_(2)(GHSV=300000 ml·h^(-1)·g^(-1)),the CO conversion remained above 95%at 220℃for 46 h.The catalysts were characterized and analyzed using various techniques.The results indicated that anatasephase TiO_(2) exhibited weak CO adsorption capacity but strong SO_(2) adsorption capacity,whereas rutilephase TiO_(2) demonstrated strong CO adsorption capacity and weak SO_(2) adsorption capacity.The presence of the anatase phase mitigated the CO self-poisoning phenomenon of the catalyst,while the biphase interface reduced the adsorption and oxidation of SO_(2) on the catalyst's surface,significantly inhibiting the deposition of TiOSO_4.Consequently,the Pt/TiO_(2)-500 catalyst displayed the highest CO catalytic activity along with superior resistance to sulfur and water.展开更多
Platinum/cerium-zirconium-sulfate（Pt/Ce-Zr-SO_4^（2-）） catalysts were prepared by wetness impregnation.Catalytic activities were evaluated from the combustion of propene and CO.Sulfate（SO_4^（2-））addition improv...Platinum/cerium-zirconium-sulfate（Pt/Ce-Zr-SO_4^（2-）） catalysts were prepared by wetness impregnation.Catalytic activities were evaluated from the combustion of propene and CO.Sulfate（SO_4^（2-））addition improved the catalytic activity significantly.When using Pt/Ce-Zr-SO_4^（2-） with 10 wt%SO_4^（2-）,the temperature for 90%conversion of propene and CO decreased by 75℃ compared with Pt/Ce-Zr.The conversion exceeded 95%at 240℃ even after 0.02%sulfur dioxide poisoning for 20 h.Temperature-programmed desorption of CO and X-ray photoelectron spectroscopy analyses revealed an improvement in Pt dispersion onto the Ce-Zr-SO_4^（2-） support,and the increased number of Pt particles built up more Pt^（-）-（SO_4^（2-））^（-） couples,which resulted in excellent activity.The increased total acidity and new Bronsted acid sites on the surface provided the Pt/Ce-Zr-SO_4^（2-） with good sulfur resistance.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
Formaldehyde(HCHO) is an important indoor pollutant.Catalytic oxidize low concentration HCHO is an effective way to eliminate indoor pollution.In this study,a series of Pt/TiO_(2) catalysts are prepared by impregnatio...Formaldehyde(HCHO) is an important indoor pollutant.Catalytic oxidize low concentration HCHO is an effective way to eliminate indoor pollution.In this study,a series of Pt/TiO_(2) catalysts are prepared by impregnation and reduced by NaBH_4.The effects of loading amount of Pt and cry stal type of TiO_(2) on the physical and chemical properties and the catalytic performance in HCHO oxidation reaction are investigated.The results show that the quantity of active site and the oxygen vacancy of catalysts increa sed with increasing Pt content,which is beneficial to promote the further performance of catalysts.Nevertheless,with the further rises of Pt content,the specific surface area further decreases,and the proportion of Pt^(2+) species on the catalyst surface which is significant to catalytic properties also decreases,causing catalytic performance decreases.Compared with the catalyst supporting on rutile,the Pt/α-TiO_(2) catalyst supporting on anatase has larger specific surface area,more Pt^(2+) phase and easier to form oxygen vacancy in the support,which cause better catalytic performance.The catalyst with Pt content of0.1 wt% and supported by anatase TiO_(2) has the best catalytic performance.The HCHO conversion efficiency reaches 98% and 100% at 50℃ and 100 ℃, and the stabilization time is longer than 140 h.展开更多
Reverse water gas shift (RWGS) reaction can serve as a pivotal stage in the CO2 conversion processes, which is vital for the utilization of CO2. In this study, RWGS reaction was performed over Pt/CeO2 catalysts at the...Reverse water gas shift (RWGS) reaction can serve as a pivotal stage in the CO2 conversion processes, which is vital for the utilization of CO2. In this study, RWGS reaction was performed over Pt/CeO2 catalysts at the temperature range of 200-500 degrees C under ambient pressure. Compared with pure CeO2, Pt/CeO2 catalysts exhibited superior RWGS activity at lower reaction temperature. Meanwhile, the calculated TOF and E-a values are approximately the same over these Pt/CeO2 catalysts pretreated under various calcination conditions, indicating that the RWGS reaction is not affected by the morphologies of anchored Pt nanoparticles or the primary crystallinity of CeO2. TPR and XPS results indicated that the incorporation of Pt promoted the reducibility of CeO2 support and remarkably increased the content of Ce 3 + sites on the catalyst surface. Furthermore, the CO TPSR-MS signal under the condition of pure CO2 flow over Pt/CeO 2 catalyst is far lower than that under the condition of adsorbed CO2 with H-2 -assisted flow, revealing that CO2 molecules adsorbed on Ce3+ active sites have difficult in generating CO directly. Meanwhile, the adsorbed CO2 with the assistance of H-2 can form formate species easily over Ce3+ active sites and then decompose into Ce3+-CO species for CO production, which was identified by in-situ FTIR. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B. V. and Science Press. All rights reserved.展开更多
A 0.5 wt.% Pt/TiO2 catalyst was prepared and used for the low-temperature selective catalytic reduction （SCR） of NO with C3H6 in the presence of excess oxygen. The effects of Pt loading and 02 concentration on Pt/Ti...A 0.5 wt.% Pt/TiO2 catalyst was prepared and used for the low-temperature selective catalytic reduction （SCR） of NO with C3H6 in the presence of excess oxygen. The effects of Pt loading and 02 concentration on Pt/TiO2 catalytic performance for low-temperature SCR were investigated. It was found that optimal Pt loading was 0.5 wt.% and excess 02 favored low-temperature SCR of NOx. The mechanism of low-temperature SCR of NO with C3H6 was investigated with respect to the behavior of adsorbed species over Pt/TiO2 at 150~C using in situ DRIFTS. The results indicated that surface nitrosyl species （Pt~＋-NO and Ti3＋-NO） and pt2＋-CO are main reaction intermediates during the interactions of NO, C3H6 and 02. A simplified NO decomposition mechanism for the low-temperature SCR of NO with C3H6 was proposed.展开更多
Catalyst support is extremely important for future fuel cell devices.In this work,we developed doubleshelled C/TiO2(DSCT)hollow spheres as an excellent catalyst support via a template-directed method.The combination o...Catalyst support is extremely important for future fuel cell devices.In this work,we developed doubleshelled C/TiO2(DSCT)hollow spheres as an excellent catalyst support via a template-directed method.The combination of hollow structure,TiO2 shell and carbon layer results in excellent electron conductivity,electrocatalytic activity,and chemical stability.These uniformed DSCT hollow spheres are used as catalyst support to synthesize Pt/DSCT hollow spheres electrocatalyst.The resulting Pt/DSCT hollow spheres exhibited high catalytic performance with a current density of 462 mA mg^-1 for methanol oxidation reaction,which is 2.52 times higher than that of the commercial Pt/C.Furthermore,the increased tolerance to carbonaceous poisoning with a higher If/Ibratio and a better long-term stability in acid media suggests that the DSCT hollow sphere is a promising C/TiO2-based catalyst support for direct methanol fuel cells applications.展开更多
This study was focused on the influence of active oxygen on the performance of Pt/CeO2 catalysts for CO oxidation. A series of CeO2 supports with different contents of active oxygen were obtained by adding surfactant ...This study was focused on the influence of active oxygen on the performance of Pt/CeO2 catalysts for CO oxidation. A series of CeO2 supports with different contents of active oxygen were obtained by adding surfactant at different synthesis steps. 0.25 wt% Pt was loaded on these CeO2 supports by incipientwetness impregnation methods. The catalysts were characterized by N2 adsorption, X-ray diffraction（XRD）, high-resolution transmission electron microscopy（HRTEM）, H2 temperature-programmed reduction（H2-TPR）, dynamic oxygen storage capacity（DOSC） and in-situ DRIFTS technologies. For S-f supports, the surfactant was added into the solution before spray-drying in the synthesis process, which facilitates more active oxygen formation on the surface of CeO2. After loading Pt, the more active oxygen on CeO2 contributes to dispersing Pt species and enhancing the CO oxidation activity. As for the aged samples,Pt-R-h shows the highest activity above 190 ℃ because of the presence of more partly oxidized Pt^（δ＋） species. Thus the activity is also influenced by the states of Pt and the Pt^（δ＋） species may contribute to the high activity at elevated temperature.展开更多
In this investigation, Pt–Ba–Ce/c-Al2O3 catalysts were prepared by incipient wetness impregnation and experiments were performed to evaluate the influence of H2 on the evolution mechanism of nitrogen oxides (NOx) st...In this investigation, Pt–Ba–Ce/c-Al2O3 catalysts were prepared by incipient wetness impregnation and experiments were performed to evaluate the influence of H2 on the evolution mechanism of nitrogen oxides (NOx) storage and reduction (NSR). The physical and chemical properties of the Pt–Ba–Ce/c- Al2O3 catalysts were studied using a combination of characterization techniques, which showed that PtOx, CeO2, and BaCO3, whose peaks were observed in X-ray diffraction (XRD) spectra, dispersed well on the c-Al2O3, as shown by transmission electron microscope (TEM), and that the difference between Ce3+ and Ce4+, as detected by X-ray photoelectron spectroscopy (XPS), facilitated the migration of active oxygen over the catalyst. In the process of a complete NSR experiment, the NOx storage capability was greatly enhanced in the temperature range of 250–350℃, and reached a maximum value of 315.3μmol·gcat^-1 at 350℃, which was ascribed to the increase in NO2 yield. In a lean and rich cycling experiment, the results showed that NOx storage efficiency and conversion were increased when the time of H2 exposure (i.e., 30, 45, and 60 s) was extended. The maximum NOx conversion of the catalyst reached 83.5% when the duration of the lean and rich phases was 240 and 60 s, respectively. The results revealed that increasing the content of H2 by an appropriate amount was favorable to the NSR mechanism due to increased decomposition of nitrate or nitrite, and the refreshing of trapping sites for the next cycle of NSR.展开更多
The water gas shift reaction is of vital significance for the generation and transition of energy due to the application in hydrogen production and industries such as ammonia synthesis and fuel cells.The influence of ...The water gas shift reaction is of vital significance for the generation and transition of energy due to the application in hydrogen production and industries such as ammonia synthesis and fuel cells.The influence of support doping and bimetallic alloying on the catalytic performance of Pt/Ce O_(2)-based nanocatalysts in water gas shift reaction was reported in this work.Various lanthanide ions and 3d transition metals were respectively introduced into the Ce O_(2)support or Pt to form Pt/Ce O_(2):Ln(Ln=La,Nd,Gd,Tb,Yb)and Pt M/Ce O_(2)(M=Fe,Co,Ni)nanocatalysts.The sample of Pt/Ce O_(2):Tb showed the highest activity(TOF at 200℃=0.051 s^(-1))among the Pt/Ce O_(2):Ln and the undoped Pt/Ce O_(2)catalysts.Besides,the sample of Pt Fe/Ce O_(2)exhibited the highest activity(TOF at 200℃=0.12 s^(-1))among Pt M/Ce O_(2)catalysts.The results of the multiple characterizations indicated that the catalytic activity of Pt/Ce O_(2):Ln catalysts was closely correlated with the amount of oxygen vacancies in doped ceria support.However,the different activity of Pt M/Ce O_(2)bimetallic catalysts was owing to the various Pt oxidation states of the bimetals dispersed on ceria.The study of the reaction pathway indicated that both the samples of Pt/Ce O_(2)and Pt/Ce O_(2):Tb catalyzed the reaction through the formate pathway,and the enhanced activity of the latter derived from the increased concentration of oxygen vacancies along with promoted water dissociation.As for the sample of Pt Fe/Ce O_(2),its catalytic mechanism was the carboxyl route with a higher reaction rate due to the moderate valence of Pt along with improved CO activation.展开更多
A core shell structured C@MoxTi1-xO2-δnanocrystal with a functionalized interface(C@MTNC-FI)was fabricated via the hydrothermal method with subsequent annealing derived from tetrabutyl orthotitanate.The formation of ...A core shell structured C@MoxTi1-xO2-δnanocrystal with a functionalized interface(C@MTNC-FI)was fabricated via the hydrothermal method with subsequent annealing derived from tetrabutyl orthotitanate.The formation of anatase TiO2 was inhibited by the simultaneous presence of the hydrothermal etching/regrowth process,infiltration of Mo dopants and carbon coating,which endows the C@MTNC-FI with an ultrafine crystalline architecture that has a Mo-functionalized interface and carbon-coated shell.Pt Ru nanoparticles(NPs)were supported on C@MTNC-FI by employing a microwave-assisted polyol process(MAPP).The obtained Pt Ru/C@MTNC-FI catalyst has 2.68 times higher mass activity towards methanol electrooxidation than that of the un-functionalized catalyst(Pt Ru/C@TNC)and 1.65 times higher mass activity than that of Pt Ru/C catalyst with over 25%increase in durability.The improved catalytic performance is due to several aspects including ultrafine crystals of TiO2 with abundant grain boundaries,Mofunctionalized interface with enhanced electron interactions,and core shell architecture with excellent electrical transport properties.This work suggests the potential application of an interface-functionalized crystalline material as a sustainable and clean energy solution.展开更多
A λ-MnO2 supported Pt nanocatalyst（5 wt.% Pt/λ-MnO2） was synthesized using a facile approach.X-ray diffraction（XRD）, X-ray photoelectron spectroscopy（XPS）, scanning electronic microscope（SEM）, transmission e...A λ-MnO2 supported Pt nanocatalyst（5 wt.% Pt/λ-MnO2） was synthesized using a facile approach.X-ray diffraction（XRD）, X-ray photoelectron spectroscopy（XPS）, scanning electronic microscope（SEM）, transmission electron microscopy（TEM）, and energy disperse spectroscopy（EDS） were used for catalyst structure and morphology characterization, which showed that the metallic Pt particles were attached on a λ-MnO2 surface through the interaction between Pt and λ-MnO2.Cyclic voltammetry（CV） was used to test the catalytic activity of Pt/λ-MnO2 toward methanol oxidation, which showed that Pt/λ-MnO2 catalyst has much higher catalytic activity than baseline Pt/C catalyst.展开更多
Pt/ZrO_(2)catalysts promoted with MoO_(3)and Nb_(2)O_(5)were tested for the combustion of short-chain alkanes(namely,methane,ethane,propane,and n-hexane).For short-chain alkane combustion,the inhibition of MoO_(3)(for...Pt/ZrO_(2)catalysts promoted with MoO_(3)and Nb_(2)O_(5)were tested for the combustion of short-chain alkanes(namely,methane,ethane,propane,and n-hexane).For short-chain alkane combustion,the inhibition of MoO_(3)(for the methane reaction)dramatically transformed to promotion(for the ethane,propane,and n-hexane reactions)as the carbon chain length increased,whereas the remarkable promotion of Nb_(2)O_(5)gradually weakened with an increase in the carbon chain length.Based on a detailed study of the oxidation reactions of methane and propane over the catalysts,the different roles of the promoters in the reactions were ascribed to differences in the acidic properties of the surface and the oxidation or reduction states of the Pt species.The MoO_(3)promoter could decorate the surface of the Pt species for a Pt-Mo/ZrO_(2)catalyst,whereas the Nb_(2)O_(5)promoter on the support could be partially covered by Pt particles for a Pt-Nb/ZrO_(2)catalyst.The formation of accessible Pt-MoO_(3)interfacial sites,a high concentration of metallic Pt species,and a high surface acidity in Pt-Mo/ZrO_(2)were responsible for the enhanced activity for catalytic propane combustion.The lack of enough accessible Pt-Nb_(2)O_(5)interfacial sites but an enhanced surface acid sites in Pt-Nb/ZrO_(2)explained the slight improvement in activity for catalytic propane combustion.However,the stabilized Pt^(n+)species in Pt-Nb/ZrO_(2)were responsible for the much-improved activity for methane combustion,whereas the Pt^(n+)species in Pt-Mo/ZrO_(2)could be reduced during the oxidation reaction,and the fewer exposed surface Pt species because of MoO_(3)decoration accounted for the inhibited activity for methane combustion.In addition,it can be concluded that MoO_(3)promotion is favorable for the activation of C-C bonds,whereas Nb_(2)O_(5)promotion is more beneficial for the activation of C-H bonds with high energy.展开更多
NOx storage and reduction(NSR)technology has been regarded as one of the most promising strategies for the removal of nitric oxides(NOx)from lean-burn engines,and the potential of the plasma catalysis method for NOx r...NOx storage and reduction(NSR)technology has been regarded as one of the most promising strategies for the removal of nitric oxides(NOx)from lean-burn engines,and the potential of the plasma catalysis method for NOx reduction has been confirmed in the past few decades.This work reports the NSR of nitric oxide(NO)by combining non-thermal plasma(NTP)and Co/Pt/Ba/γ-Al2O3(Co/PBA)catalyst using methane as a reductant.The experimental results reveal that the NOx conversion of NSR assisted by NTP is notably enhanced compared to the catalytic efficiency obtained from NSR in the range of 150°C–350°C,and NOx conversion of the 8%Co/PBA catalyst reaches 96.8%at 350°C.Oxygen(O_(2))has a significant effect on the removal of NOx,and the NOx conversion increases firstly and then decreases when the O_(2)concentration ranges from 2%to 10%.Water vapor reduces the NOx storage capacity of Co/PBA catalysts on account of the competition for adsorption sites on the surface of Co/PBA catalysts.There is a negative correlation between sulfur dioxide(SO_(2))and NOx conversion in the NTP system,and the 8%Co/PBA catalyst exhibits higher NOx conversion compared to other catalysts,which shows that Co has a certain SO_(2)resistance.展开更多
Formaldehyde(HCHO) and carbon monoxide(CO) are both common air pollutants and hazardous to human body. It is imperative to develop the catalyst that is able to efficiently remove these pollutants. In this work, we act...Formaldehyde(HCHO) and carbon monoxide(CO) are both common air pollutants and hazardous to human body. It is imperative to develop the catalyst that is able to efficiently remove these pollutants. In this work, we activated Pt-MnO_(2)under different conditions for highly active oxidation of HCHO and CO, and the catalyst activated under CO displayed superior performance. A suite of complementary characterizations revealed that the catalyst activated with CO created the highly dispersed Pt nanoparticles to maintain a more positively charged state of Pt, which appropriately weakens the Mn-O bonding strength in the adjacent region of Pt for efficient supply of active oxygen during the reaction. Compared with other catalysts activated under different conditions, the CO-activated Pt-MnO_(2)displays much higher activity for oxidation of HCHO and CO. This research contributes to elucidating the mechanism for regulating the oxidation activity of Pt-based catalyst.展开更多
The electronic modification effect of various metal oxides over Pt-Al;O;catalyst andthe relationships between the polarizing force of cations（PFC）and the electrophiliccharacter（EC）and catalytic performances（CP）o...The electronic modification effect of various metal oxides over Pt-Al;O;catalyst andthe relationships between the polarizing force of cations（PFC）and the electrophiliccharacter（EC）and catalytic performances（CP）of promoted Pt catalyst have been studiecby competitive hydrogenation reaction method（CHRM）and test reaction,i.e.hydrogena-tion of benzene and hydrogenolysis of cyclopentane.展开更多
文摘Supported metal catalysts are the backbone of heterogeneous catalysis,playing a crucial role in the modern chemical industry.Metal-support interactions(MSIs)are known important in determining the catalytic performance of supported metal catalysts.This is particularly true for single-atom catalysts(SACs)and pseudo-single-atom catalysts(pseudo-SACs),where all metal atoms are dispersed on,and interact directly with the support.Consequently,the MSI of SACs and pseudo-SACs are theoretically more sensitive to modulation compared to that of traditional nanoparticle catalysts.In this work,we experimentally demonstrated this hypothesis by an observed size-dependent MSI modulation.We fabricated CoFe_(2)O_(4) supported Pt pseudo-SACs and nanoparticle catalysts,followed by a straightforward water treatment process.It was found that the covalent strong metal-support interaction(CMSI)in pseudo-SACs can be weakened,leading to a significant activity improvement in methane combustion reaction.This finding aligns with our recent observation of CoFe_(2)O_(4) supported Pt SACs.By contrast,the MSI in Pt nanoparticle catalyst was barely affected by the water treatment,giving rise to almost unchanged catalytic performance.This work highlights the critical role of metal size in determining the MSI modulation,offering a novel strategy for tuning the catalytic performance of SACs and pseudo-SACs by fine-tuning their MSIs.
基金financially supported by the National Key Research&Development Program of China(2024YFC3908400)the National Natural Science Foundation of China(U21B2099)Fundamental Research Funds for the Central Universities,Ocean University of China(202364004)。
文摘Catalytic oxidation is an effective strategy for eliminating CO pollutant.Pt/TiO_(2) catalyst are one of the most active catalysts as used,but facing the issue of sulfur and water deactivation.In this study,TiO_(2) was synthesized using a sol-gel method,while Pt/TiO_(2) was prepared by impregnation method.By varying the calcination temperature of the TiO_(2) support,Pt/TiO_(2) catalysts with different proportions of anatase and rutile phases were synthesized.At the calcination temperature of 500℃,the catalysts exhibited approximately equal proportions of anatase and rutile,resulting in exceptional catalytic activity for CO oxidation,as well as improved resistance to sulfur and water in the flue gas.Consequently,the Pt/TiO_(2)-500 catalyst achieved a CO conversion of 93%at 160℃.Even under conditions of 8%(vol)H_(2)O and 0.016%(vol)SO_(2)(GHSV=300000 ml·h^(-1)·g^(-1)),the CO conversion remained above 95%at 220℃for 46 h.The catalysts were characterized and analyzed using various techniques.The results indicated that anatasephase TiO_(2) exhibited weak CO adsorption capacity but strong SO_(2) adsorption capacity,whereas rutilephase TiO_(2) demonstrated strong CO adsorption capacity and weak SO_(2) adsorption capacity.The presence of the anatase phase mitigated the CO self-poisoning phenomenon of the catalyst,while the biphase interface reduced the adsorption and oxidation of SO_(2) on the catalyst's surface,significantly inhibiting the deposition of TiOSO_4.Consequently,the Pt/TiO_(2)-500 catalyst displayed the highest CO catalytic activity along with superior resistance to sulfur and water.
基金supported by the National Natural Science Foundation of China(21506194,21676255)the Provincial Natural Science Foundation of Zhejiang Province(LY16B070011)the Commission of Science and Technology of Zhejiang Province(2017C33106,2017C03007)~~
文摘Platinum/cerium-zirconium-sulfate（Pt/Ce-Zr-SO_4^（2-）） catalysts were prepared by wetness impregnation.Catalytic activities were evaluated from the combustion of propene and CO.Sulfate（SO_4^（2-））addition improved the catalytic activity significantly.When using Pt/Ce-Zr-SO_4^（2-） with 10 wt%SO_4^（2-）,the temperature for 90%conversion of propene and CO decreased by 75℃ compared with Pt/Ce-Zr.The conversion exceeded 95%at 240℃ even after 0.02%sulfur dioxide poisoning for 20 h.Temperature-programmed desorption of CO and X-ray photoelectron spectroscopy analyses revealed an improvement in Pt dispersion onto the Ce-Zr-SO_4^（2-） support,and the increased number of Pt particles built up more Pt^（-）-（SO_4^（2-））^（-） couples,which resulted in excellent activity.The increased total acidity and new Bronsted acid sites on the surface provided the Pt/Ce-Zr-SO_4^（2-） with good sulfur resistance.
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 CAS (Chinese Academy of Sciences) Strategic Priority Research Program (XDA-21020500)。
文摘Formaldehyde(HCHO) is an important indoor pollutant.Catalytic oxidize low concentration HCHO is an effective way to eliminate indoor pollution.In this study,a series of Pt/TiO_(2) catalysts are prepared by impregnation and reduced by NaBH_4.The effects of loading amount of Pt and cry stal type of TiO_(2) on the physical and chemical properties and the catalytic performance in HCHO oxidation reaction are investigated.The results show that the quantity of active site and the oxygen vacancy of catalysts increa sed with increasing Pt content,which is beneficial to promote the further performance of catalysts.Nevertheless,with the further rises of Pt content,the specific surface area further decreases,and the proportion of Pt^(2+) species on the catalyst surface which is significant to catalytic properties also decreases,causing catalytic performance decreases.Compared with the catalyst supporting on rutile,the Pt/α-TiO_(2) catalyst supporting on anatase has larger specific surface area,more Pt^(2+) phase and easier to form oxygen vacancy in the support,which cause better catalytic performance.The catalyst with Pt content of0.1 wt% and supported by anatase TiO_(2) has the best catalytic performance.The HCHO conversion efficiency reaches 98% and 100% at 50℃ and 100 ℃, and the stabilization time is longer than 140 h.
基金National Natural Science Foundation of China (nos.21476226 and 21506204)National Key Projects for Fundamental Research and Development of China (2016YFB0600902)+1 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences (XDB17020400)the Youth Innovation Promotion Association CAS for financial support
文摘Reverse water gas shift (RWGS) reaction can serve as a pivotal stage in the CO2 conversion processes, which is vital for the utilization of CO2. In this study, RWGS reaction was performed over Pt/CeO2 catalysts at the temperature range of 200-500 degrees C under ambient pressure. Compared with pure CeO2, Pt/CeO2 catalysts exhibited superior RWGS activity at lower reaction temperature. Meanwhile, the calculated TOF and E-a values are approximately the same over these Pt/CeO2 catalysts pretreated under various calcination conditions, indicating that the RWGS reaction is not affected by the morphologies of anchored Pt nanoparticles or the primary crystallinity of CeO2. TPR and XPS results indicated that the incorporation of Pt promoted the reducibility of CeO2 support and remarkably increased the content of Ce 3 + sites on the catalyst surface. Furthermore, the CO TPSR-MS signal under the condition of pure CO2 flow over Pt/CeO 2 catalyst is far lower than that under the condition of adsorbed CO2 with H-2 -assisted flow, revealing that CO2 molecules adsorbed on Ce3+ active sites have difficult in generating CO directly. Meanwhile, the adsorbed CO2 with the assistance of H-2 can form formate species easily over Ce3+ active sites and then decompose into Ce3+-CO species for CO production, which was identified by in-situ FTIR. (C) 2016 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B. V. and Science Press. All rights reserved.
基金supported by the National Natural Science Foundation of China (No. 20807027)the Special Foundation of Nanometer Technology from Shanghai Municipal Science and Technology Commission of China(No. 0752 nm005)
文摘A 0.5 wt.% Pt/TiO2 catalyst was prepared and used for the low-temperature selective catalytic reduction （SCR） of NO with C3H6 in the presence of excess oxygen. The effects of Pt loading and 02 concentration on Pt/TiO2 catalytic performance for low-temperature SCR were investigated. It was found that optimal Pt loading was 0.5 wt.% and excess 02 favored low-temperature SCR of NOx. The mechanism of low-temperature SCR of NO with C3H6 was investigated with respect to the behavior of adsorbed species over Pt/TiO2 at 150~C using in situ DRIFTS. The results indicated that surface nitrosyl species （Pt~＋-NO and Ti3＋-NO） and pt2＋-CO are main reaction intermediates during the interactions of NO, C3H6 and 02. A simplified NO decomposition mechanism for the low-temperature SCR of NO with C3H6 was proposed.
基金supported by the Scholarship from China Scholarship Council(CSC)(Grant no.201604910621)。
文摘Catalyst support is extremely important for future fuel cell devices.In this work,we developed doubleshelled C/TiO2(DSCT)hollow spheres as an excellent catalyst support via a template-directed method.The combination of hollow structure,TiO2 shell and carbon layer results in excellent electron conductivity,electrocatalytic activity,and chemical stability.These uniformed DSCT hollow spheres are used as catalyst support to synthesize Pt/DSCT hollow spheres electrocatalyst.The resulting Pt/DSCT hollow spheres exhibited high catalytic performance with a current density of 462 mA mg^-1 for methanol oxidation reaction,which is 2.52 times higher than that of the commercial Pt/C.Furthermore,the increased tolerance to carbonaceous poisoning with a higher If/Ibratio and a better long-term stability in acid media suggests that the DSCT hollow sphere is a promising C/TiO2-based catalyst support for direct methanol fuel cells applications.
基金Project supported by the National key research and development program(2016YFC0204901)the National Natural Science Foundation of China(21576207)+1 种基金the Introduction Of Talent and Technology Cooperation Plan Of Tianjin(14RCGFGX00849)GM Global Research&Development(GAC 1539)
文摘This study was focused on the influence of active oxygen on the performance of Pt/CeO2 catalysts for CO oxidation. A series of CeO2 supports with different contents of active oxygen were obtained by adding surfactant at different synthesis steps. 0.25 wt% Pt was loaded on these CeO2 supports by incipientwetness impregnation methods. The catalysts were characterized by N2 adsorption, X-ray diffraction（XRD）, high-resolution transmission electron microscopy（HRTEM）, H2 temperature-programmed reduction（H2-TPR）, dynamic oxygen storage capacity（DOSC） and in-situ DRIFTS technologies. For S-f supports, the surfactant was added into the solution before spray-drying in the synthesis process, which facilitates more active oxygen formation on the surface of CeO2. After loading Pt, the more active oxygen on CeO2 contributes to dispersing Pt species and enhancing the CO oxidation activity. As for the aged samples,Pt-R-h shows the highest activity above 190 ℃ because of the presence of more partly oxidized Pt^（δ＋） species. Thus the activity is also influenced by the states of Pt and the Pt^（δ＋） species may contribute to the high activity at elevated temperature.
基金the National Natural Science Foundation of China (51676090)the Natural Science Foundation of Jiangsu Province (BK20150513), and the Six Talent Peaks Project in Jiangsu Province.
文摘In this investigation, Pt–Ba–Ce/c-Al2O3 catalysts were prepared by incipient wetness impregnation and experiments were performed to evaluate the influence of H2 on the evolution mechanism of nitrogen oxides (NOx) storage and reduction (NSR). The physical and chemical properties of the Pt–Ba–Ce/c- Al2O3 catalysts were studied using a combination of characterization techniques, which showed that PtOx, CeO2, and BaCO3, whose peaks were observed in X-ray diffraction (XRD) spectra, dispersed well on the c-Al2O3, as shown by transmission electron microscope (TEM), and that the difference between Ce3+ and Ce4+, as detected by X-ray photoelectron spectroscopy (XPS), facilitated the migration of active oxygen over the catalyst. In the process of a complete NSR experiment, the NOx storage capability was greatly enhanced in the temperature range of 250–350℃, and reached a maximum value of 315.3μmol·gcat^-1 at 350℃, which was ascribed to the increase in NO2 yield. In a lean and rich cycling experiment, the results showed that NOx storage efficiency and conversion were increased when the time of H2 exposure (i.e., 30, 45, and 60 s) was extended. The maximum NOx conversion of the catalyst reached 83.5% when the duration of the lean and rich phases was 240 and 60 s, respectively. The results revealed that increasing the content of H2 by an appropriate amount was favorable to the NSR mechanism due to increased decomposition of nitrate or nitrite, and the refreshing of trapping sites for the next cycle of NSR.
基金financial support from the National Natural Science Foundation of China(21832001 and 21771009)the Beijing National Laboratory for Molecular Sciences(BNLMSCXXM-202104)。
文摘The water gas shift reaction is of vital significance for the generation and transition of energy due to the application in hydrogen production and industries such as ammonia synthesis and fuel cells.The influence of support doping and bimetallic alloying on the catalytic performance of Pt/Ce O_(2)-based nanocatalysts in water gas shift reaction was reported in this work.Various lanthanide ions and 3d transition metals were respectively introduced into the Ce O_(2)support or Pt to form Pt/Ce O_(2):Ln(Ln=La,Nd,Gd,Tb,Yb)and Pt M/Ce O_(2)(M=Fe,Co,Ni)nanocatalysts.The sample of Pt/Ce O_(2):Tb showed the highest activity(TOF at 200℃=0.051 s^(-1))among the Pt/Ce O_(2):Ln and the undoped Pt/Ce O_(2)catalysts.Besides,the sample of Pt Fe/Ce O_(2)exhibited the highest activity(TOF at 200℃=0.12 s^(-1))among Pt M/Ce O_(2)catalysts.The results of the multiple characterizations indicated that the catalytic activity of Pt/Ce O_(2):Ln catalysts was closely correlated with the amount of oxygen vacancies in doped ceria support.However,the different activity of Pt M/Ce O_(2)bimetallic catalysts was owing to the various Pt oxidation states of the bimetals dispersed on ceria.The study of the reaction pathway indicated that both the samples of Pt/Ce O_(2)and Pt/Ce O_(2):Tb catalyzed the reaction through the formate pathway,and the enhanced activity of the latter derived from the increased concentration of oxygen vacancies along with promoted water dissociation.As for the sample of Pt Fe/Ce O_(2),its catalytic mechanism was the carboxyl route with a higher reaction rate due to the moderate valence of Pt along with improved CO activation.
基金the National Natural Science Foundation of China (Grant Nos. 21273058, 21673064, 51802059 and 21503059)China Postdoctoral Science Foundation (Grant Nos. 2018M631938, 2018T110307 and 2017M621284)+1 种基金Heilongjiang Postdoctoral Fund (LBH-Z17074)Fundamental Research Funds for the Central Universities (Grant No. HIT. NSRIF. 2019040 and 2019041)
文摘A core shell structured C@MoxTi1-xO2-δnanocrystal with a functionalized interface(C@MTNC-FI)was fabricated via the hydrothermal method with subsequent annealing derived from tetrabutyl orthotitanate.The formation of anatase TiO2 was inhibited by the simultaneous presence of the hydrothermal etching/regrowth process,infiltration of Mo dopants and carbon coating,which endows the C@MTNC-FI with an ultrafine crystalline architecture that has a Mo-functionalized interface and carbon-coated shell.Pt Ru nanoparticles(NPs)were supported on C@MTNC-FI by employing a microwave-assisted polyol process(MAPP).The obtained Pt Ru/C@MTNC-FI catalyst has 2.68 times higher mass activity towards methanol electrooxidation than that of the un-functionalized catalyst(Pt Ru/C@TNC)and 1.65 times higher mass activity than that of Pt Ru/C catalyst with over 25%increase in durability.The improved catalytic performance is due to several aspects including ultrafine crystals of TiO2 with abundant grain boundaries,Mofunctionalized interface with enhanced electron interactions,and core shell architecture with excellent electrical transport properties.This work suggests the potential application of an interface-functionalized crystalline material as a sustainable and clean energy solution.
基金supported by the Funding Project for Academic Human Resources Development in Institutions of Higher Learning under the Jurisdiction of Beijing Municipality, Beijing Natural Science Foundation (No. 207001)the Major State Basic Research and Development Program of China (No. 2002CB211807)
文摘A λ-MnO2 supported Pt nanocatalyst（5 wt.% Pt/λ-MnO2） was synthesized using a facile approach.X-ray diffraction（XRD）, X-ray photoelectron spectroscopy（XPS）, scanning electronic microscope（SEM）, transmission electron microscopy（TEM）, and energy disperse spectroscopy（EDS） were used for catalyst structure and morphology characterization, which showed that the metallic Pt particles were attached on a λ-MnO2 surface through the interaction between Pt and λ-MnO2.Cyclic voltammetry（CV） was used to test the catalytic activity of Pt/λ-MnO2 toward methanol oxidation, which showed that Pt/λ-MnO2 catalyst has much higher catalytic activity than baseline Pt/C catalyst.
文摘Pt/ZrO_(2)catalysts promoted with MoO_(3)and Nb_(2)O_(5)were tested for the combustion of short-chain alkanes(namely,methane,ethane,propane,and n-hexane).For short-chain alkane combustion,the inhibition of MoO_(3)(for the methane reaction)dramatically transformed to promotion(for the ethane,propane,and n-hexane reactions)as the carbon chain length increased,whereas the remarkable promotion of Nb_(2)O_(5)gradually weakened with an increase in the carbon chain length.Based on a detailed study of the oxidation reactions of methane and propane over the catalysts,the different roles of the promoters in the reactions were ascribed to differences in the acidic properties of the surface and the oxidation or reduction states of the Pt species.The MoO_(3)promoter could decorate the surface of the Pt species for a Pt-Mo/ZrO_(2)catalyst,whereas the Nb_(2)O_(5)promoter on the support could be partially covered by Pt particles for a Pt-Nb/ZrO_(2)catalyst.The formation of accessible Pt-MoO_(3)interfacial sites,a high concentration of metallic Pt species,and a high surface acidity in Pt-Mo/ZrO_(2)were responsible for the enhanced activity for catalytic propane combustion.The lack of enough accessible Pt-Nb_(2)O_(5)interfacial sites but an enhanced surface acid sites in Pt-Nb/ZrO_(2)explained the slight improvement in activity for catalytic propane combustion.However,the stabilized Pt^(n+)species in Pt-Nb/ZrO_(2)were responsible for the much-improved activity for methane combustion,whereas the Pt^(n+)species in Pt-Mo/ZrO_(2)could be reduced during the oxidation reaction,and the fewer exposed surface Pt species because of MoO_(3)decoration accounted for the inhibited activity for methane combustion.In addition,it can be concluded that MoO_(3)promotion is favorable for the activation of C-C bonds,whereas Nb_(2)O_(5)promotion is more beneficial for the activation of C-H bonds with high energy.
基金by the National Engineering Laboratory for Mobile Source Emission Control Technology(No.NELMS2019A13)the National Key Research and Development Project of China(No.2019YFC1805505)+2 种基金the Shanxi Province Bidding Project(No.20191101007)the Major Science and Technology Projects of Shanxi Province(No.20181102017)State Key Laboratory of Organic Geochemistry(No.SKLOG-201909)。
文摘NOx storage and reduction(NSR)technology has been regarded as one of the most promising strategies for the removal of nitric oxides(NOx)from lean-burn engines,and the potential of the plasma catalysis method for NOx reduction has been confirmed in the past few decades.This work reports the NSR of nitric oxide(NO)by combining non-thermal plasma(NTP)and Co/Pt/Ba/γ-Al2O3(Co/PBA)catalyst using methane as a reductant.The experimental results reveal that the NOx conversion of NSR assisted by NTP is notably enhanced compared to the catalytic efficiency obtained from NSR in the range of 150°C–350°C,and NOx conversion of the 8%Co/PBA catalyst reaches 96.8%at 350°C.Oxygen(O_(2))has a significant effect on the removal of NOx,and the NOx conversion increases firstly and then decreases when the O_(2)concentration ranges from 2%to 10%.Water vapor reduces the NOx storage capacity of Co/PBA catalysts on account of the competition for adsorption sites on the surface of Co/PBA catalysts.There is a negative correlation between sulfur dioxide(SO_(2))and NOx conversion in the NTP system,and the 8%Co/PBA catalyst exhibits higher NOx conversion compared to other catalysts,which shows that Co has a certain SO_(2)resistance.
基金supported by the National Natural Science Foundation of China (Nos. 22025604, 21976196, 21972170 and 22072184)。
文摘Formaldehyde(HCHO) and carbon monoxide(CO) are both common air pollutants and hazardous to human body. It is imperative to develop the catalyst that is able to efficiently remove these pollutants. In this work, we activated Pt-MnO_(2)under different conditions for highly active oxidation of HCHO and CO, and the catalyst activated under CO displayed superior performance. A suite of complementary characterizations revealed that the catalyst activated with CO created the highly dispersed Pt nanoparticles to maintain a more positively charged state of Pt, which appropriately weakens the Mn-O bonding strength in the adjacent region of Pt for efficient supply of active oxygen during the reaction. Compared with other catalysts activated under different conditions, the CO-activated Pt-MnO_(2)displays much higher activity for oxidation of HCHO and CO. This research contributes to elucidating the mechanism for regulating the oxidation activity of Pt-based catalyst.
文摘The electronic modification effect of various metal oxides over Pt-Al;O;catalyst andthe relationships between the polarizing force of cations（PFC）and the electrophiliccharacter（EC）and catalytic performances（CP）of promoted Pt catalyst have been studiecby competitive hydrogenation reaction method（CHRM）and test reaction,i.e.hydrogena-tion of benzene and hydrogenolysis of cyclopentane.
