Teroolymerization of enichlorohydrin(ECH)-maleic anhydride(MAn)-carbon dioxide(CO;) was carried out by using Y(P;);-Al(i-Bu);as catalyst for the first time.The terpolymersobtained were characterized by IR and;...Teroolymerization of enichlorohydrin(ECH)-maleic anhydride(MAn)-carbon dioxide(CO;) was carried out by using Y(P;);-Al(i-Bu);as catalyst for the first time.The terpolymersobtained were characterized by IR and;H-NMR.It was foundthat the composition of the teroolymer was influenced by theaddition mode,initial monomer charge ratio,etc.展开更多
A new catalyst system was used in the synthesis of polyethylene terephthalate(PET) and its copolymers, which involved a Ln 3+ containing compound. The catalytic effects were studied, and it was found that the dir...A new catalyst system was used in the synthesis of polyethylene terephthalate(PET) and its copolymers, which involved a Ln 3+ containing compound. The catalytic effects were studied, and it was found that the direct esterification reaction of terephthalate acid(TPA) with ethylene glycol(EG) can be accelerated by the addition of Ln 3+ containing compound, which acts as a promoter of the catalyst Sb 2O 3 in polycondensation of bis hydroxyethyl terephthalate(BHET).展开更多
The catalytic effectsof Ln3+ on synthesis of polyethyleneterephthalate and its copolyesterswere studied. The direct esterification reaction of terephthalate acidwith ethylene glycol can be accelerated hy addition of L...The catalytic effectsof Ln3+ on synthesis of polyethyleneterephthalate and its copolyesterswere studied. The direct esterification reaction of terephthalate acidwith ethylene glycol can be accelerated hy addition of Ln3+, and theLn3+, compound can be acted aspromoter of Sb2O3 in the stage ofpolycondensation. The mechanismof esterification and polycondensation by addition of Ln3+ was discussed. The thermal-stabilities ofpolyethylene terephthalate and itscopolyesters obtained by addihon ofLn3+ were also investigaed.展开更多
In order to analyze the influence of the addition of yttrium and manganese on the soot combustion performance and high temperature stability of CeO_(2) catalyst,a series of Y/Mn-modified CeO_(2) catalysts were prepare...In order to analyze the influence of the addition of yttrium and manganese on the soot combustion performance and high temperature stability of CeO_(2) catalyst,a series of Y/Mn-modified CeO_(2) catalysts were prepared.The effects of structural properties,textural properties,oxygen vacancies,Ce^(3+),surface adsorbed oxygen species,reduction properties and desorption properties of oxygen species on the activity were analyzed by various characterization methods.The results of the activity test show that the addition of manganese is beneficial to enhancement of the activity,while the addition of yttrium increases the amount of reactive oxygen species,but decreases the activity.After aging at 700℃,the activity of the CeMn catalyst decreases most sharply,while the catalytic activity of the CeY catalyst can be maintained to a certain extent.Interestingly,the addition of yttrium and manganese at the same time can stabilize the activity.The fundamental reason is that yttrium and manganese move to the surface of the solid solution after aging,which increases the reduction performance of the catalyst,thus contributing to the increase of activity.Although the activity of CeYMn catalyst decreases after aging at 800℃,it is still higher than that of other catalysts aged at 700℃.展开更多
C1 chemistry based on synthesis gas, methane, and carbon dioxide offers many routes to industrial chemicals. The reactions related to the synthesis of gas can be classified into direct and indirect approach for making...C1 chemistry based on synthesis gas, methane, and carbon dioxide offers many routes to industrial chemicals. The reactions related to the synthesis of gas can be classified into direct and indirect approach for making such products, such as acetic acid, dimethyl ether, and alcohol. Catalytic syngas processing is currently done at high temperatures and pressures, conditions that could be unfavorable for the life of the catalyst. Another issue of C1 chemistry is related to the methane-initiated process. It has been known that direct methane conversions are still suffering from low yields and selectivity of products resulting in unprofitable ways to produce products, such as higher hydrocarbons, methanol, and so on. However, many experts and researchers are still trying to find the best method to overcome these barriers, for example, by finding the best catalyst to reduce the high-energy barrier of the reactions and conduct only selective catalyst-surface reactions. The appli- cation of Yttria-Stabilized Zirconia (YSZ) and its combination with other metals for catalyzing purposes are increasing. The existence of an interesting site that acts as oxygen store could be the main reason for it. Moreover, formation of intermediate species on the surface of YSZ also contributes significantly in increasing the production of some specific products. Understanding the phenomena happening inside could be necessary. In this article, the use of YSZ for some C1 chemistry reactions was discussed and reviewed.展开更多
Al2O3 and La2O3 layers were coated respectively on a FeCrAl alloy foil by a dip-coating technique and used as the second support for the active LaMnAl11O19 hexaaluminate (HA) phase in a metallic monolithic catalyst....Al2O3 and La2O3 layers were coated respectively on a FeCrAl alloy foil by a dip-coating technique and used as the second support for the active LaMnAl11O19 hexaaluminate (HA) phase in a metallic monolithic catalyst. A sample without an intermediate layer was employed for comparison. The properties and performances of the catalyst were examined with X-ray diffraction (XRD), scanning electron microscopy (SEM), ultrasonic vibration and thermal shock techniques. Methane catalytic combustion was performed to evaluate the activity of the catalyst. The results showed that the activity and adhesion of the HA to the alloy foil could be improved with the introduction of the intermediate layer. Al2O3 provided a strong adhesion, while La2O3 weakened the interaction between the active component and alloy foil. For the activity, the catalysts made with the two different intermediate materials also showed difference.展开更多
The activity and hydrothermal stability of the Rh/Ce_(x)Zr_(1-x)O_(2)(x=0,0.05,0.3,0.5) model three-way catalysts for gasoline vehicle emissions control were investigated in this work.Among the Rh/Ce_(x)Zr_(1-x)O_(2) ...The activity and hydrothermal stability of the Rh/Ce_(x)Zr_(1-x)O_(2)(x=0,0.05,0.3,0.5) model three-way catalysts for gasoline vehicle emissions control were investigated in this work.Among the Rh/Ce_(x)Zr_(1-x)O_(2) samples with different Ce/Zr ratios,the Rh/ZrO_(2) sample exhibits a significantly better activity and hydrothermal stability than the rest of the samples.The impacts of having more Ce components in the Rh/Ce_(x)Zr_(1-x)O_(2) catalysts are associated with the strong Rh-O-Ce interaction that tends to over stabilize the rhodium species.A significant amount of such rhodium atoms can be found in the bulk of the support oxides after a hydrothermal aging at 1050℃ with 10% H_(2)O in air for 12 h.Differently,the sintering of rhodium on the surface of Rh/ZrO_(2) catalysts is the main reason for the catalyst deactivation during the hydrothermal aging.These findings provide an example where high dispersion of supported metal induced by strong metal-support interactions does not necessarily lead to high catalytic activity.展开更多
To reveal how cerium stabilizes Cu/SAPO-34 at low-temperature hydrothermal aging,various amounts of cerium were introduced into Cu/SAPO-34 via impregnation method and treated at 70℃with RH 80%for 96 h.Cerium as Ce^(3...To reveal how cerium stabilizes Cu/SAPO-34 at low-temperature hydrothermal aging,various amounts of cerium were introduced into Cu/SAPO-34 via impregnation method and treated at 70℃with RH 80%for 96 h.Cerium as Ce^(3+)and CeO_(2)nanoparticle is located on the surface of Cu/SAPO-34,and Ce^(3+)plays a vital role on gradually decreasing surface acidity and blocking defect sites with an increase of Ce loading.After hydrothermal aging,Cu/SAPO-34 with high Ce loading shows the superior SCR activity comparable to fresh samples.It is proven that the surface acidity determines the stability of the structure during hydrothermal aging process,and lower surface acidity prevents the number of Cu(Ⅱ)ions from decreasing significantly.Furthermore,the structure's stability helps the recovery of Cu(Ⅱ)ions and renders an outstanding regene ration ability.Our finding paves the way for the design of new Cu/SAPO-34catalysts with good SCR activity and long-term stability in real application.展开更多
Rare earth-doped copper-manganese mixed oxide catalysts were prepared by coprecipitation and mechanical mixing using copper sulfate, manganese sulfate, and rare-earth oxides REO (REO indicates La2O3, CeO2, Y2O3, or P...Rare earth-doped copper-manganese mixed oxide catalysts were prepared by coprecipitation and mechanical mixing using copper sulfate, manganese sulfate, and rare-earth oxides REO (REO indicates La2O3, CeO2, Y2O3, or Pr6O11) as raw materials. The samples were characterized by X-ray diffraction (XRD), temperature-programmed reduction (TPR), temperature-programmed reduc-tion of oxidized surfaces (s-TPR), and temperature-programmed desorption (TPD). Catalytic activities were tested for a water-gas shift reaction. Doping rare earth oxides did not alter the crystal structure of the original copper-manganese mixed oxides but changed the interplanar spacing, adsorption performance and reaction performance. Doping with La2O3 enhanced the activity and stability of Cu-Mn mixed oxides because of high copper distribution and fine reduction. Doping with CeO2 and Y2O3 also decreased the reduc-tion temperatures of the samples to different degrees while improving the dispersion of Cu on the surface, thus, catalytic activity was better than that of undoped Cu-Mn sample. The Pr6O11-doped sample was difficult to reduce, the dispersion of surface coppers was lowered, resulting in poor activity.展开更多
Perovskite oxide LaMnO3 was prepared by sol-gel method and the nanosize Au/LaMnO3 catalyst was prepared by deposition-precipitation(DP) method in the paper.Characterization of the catalyst sample was made by X-ray d...Perovskite oxide LaMnO3 was prepared by sol-gel method and the nanosize Au/LaMnO3 catalyst was prepared by deposition-precipitation(DP) method in the paper.Characterization of the catalyst sample was made by X-ray diffractometer(XRD),atom absorption spectra(AAS) and X-ray photoelectron spectroscopy(XPS) instrumental methods.The activity,long-term stability and the reasons for deactivation of the gold catalyst in CO oxidation were investigated.The experiment results demonstrated that the Au/LaMnO3 catalyst exhibited high stability in the ambient storage process.However,the gradual decrease in initial activity during 100 h reaction was still observed,which could be ascribed to the aggregation of gold particles and the transfer from gold ion to the metal gold.展开更多
A series of 3DOM CeMnO3 perovskite catalysts were prepared by poly(methyl methacrylate)hardtemplating-excessive impregnation method at calcination temperature of x℃(x=600,700,800)and the heating rate of y℃/min(y=1,2...A series of 3DOM CeMnO3 perovskite catalysts were prepared by poly(methyl methacrylate)hardtemplating-excessive impregnation method at calcination temperature of x℃(x=600,700,800)and the heating rate of y℃/min(y=1,2,5,10).The samples were characterized by Brunauer-Emmett-Teller method,scanning electron microscopy,transmission electron microscopy,H2-temperature programmed reduction,X-ray photoelectron spectroscopy,X-ray diffraction,moreover,the effect of the calcination process on the catalytic activity of the samples were discussed by the catalytic combustion of toluene.The results show that the 3DOM CeMnO3 catalysts calcined at 600℃promote the formation of a perovskite structure,inhibit the reduction of the Mn4+species in the catalyst with high temperature.The catalyst expresses the complete macroporous structure,large specific surface area(38.8 m^(2)/g),higher adsorption oxygen concentration and Mn4+substance concentration,with a low T90%=172℃.By preparing the catalysts at different calcination heating rates,it can be concluded that the catalyst possesses a high concentration of adsorbed oxygen and a low reduction temperature and a large specific surface area(40.42 m^(2)/g)greatly promotes adsorption stage catalytic oxidation reaction and catalytic combustion of toluene at low temperature under the heating rate of 5℃/min.When the heating rate is 1℃/min,the catalyst has a complete macroporous structure(>250 nm),which is beneficial to the exchange of macromolecular substances during the catalytic reaction and the catalyst has a high concentration of lattice oxygen suitable for the catalysis of toluene in high temperature flue gas combustion.展开更多
A series of Pd/La-Al2O3(PLA) catalysts with La-Al2O3(LA) support calcined at different temperatures(500, 700, 900 and 1050 oC) were prepared using an incipient wetness impregnation method. The activity of the fr...A series of Pd/La-Al2O3(PLA) catalysts with La-Al2O3(LA) support calcined at different temperatures(500, 700, 900 and 1050 oC) were prepared using an incipient wetness impregnation method. The activity of the fresh and hydrothermally aged PLA catalysts were tested for total oxidation of CO and C3H8. The activity of the fresh PLA catalysts for CO and C3H8 oxidation increased with increasing calcination temperature of the support, while the activities of the aged catalysts declined and became essentially the same. CO chemisorption results revealed that the suppressed activities of the aged catalysts were mainly due to the decline of palladium dispersion. The turnover frequency(TOF) of CO oxidation increased with increasing reduction ability of the catalysts, with a fresh catalyst calcined at 1050 oC having the highest value(0.048 s–1). However, the TOF of C3H8 total oxidation was affected by not only the redox properties of catalysts but also the size of Pd particle, and large Pd particles possessed higher TOF value of C3H8 oxidation, with the highest value(0.125 s–1) being obtained on an aged catalyst calcined at 500 oC.展开更多
CeO2-ZeO2 solid solutions are extensively used as oxygen storage promoters in the current automotive three-way catalysts. High thermal stability of the textural properties is one of the most important requirements for...CeO2-ZeO2 solid solutions are extensively used as oxygen storage promoters in the current automotive three-way catalysts. High thermal stability of the textural properties is one of the most important requirements for practical application since temperatures up to 1273 K are easily experienced by these materials under real working conditions. In the present paper, we investigated how hydrothermal treatments applied to cakes of doped and undoped ZrO2-rich CeO2-ZrO2 precursors might improve the thermal stability of the final CeO2-ZrO2 solid solution. A rationale was developed that allowed to correlate the morphology of the hydrothermaUy treated cake with the thermal stability at 1273 K of the final product, which did not depend on the composition of the mixed oxides.展开更多
文摘Teroolymerization of enichlorohydrin(ECH)-maleic anhydride(MAn)-carbon dioxide(CO;) was carried out by using Y(P;);-Al(i-Bu);as catalyst for the first time.The terpolymersobtained were characterized by IR and;H-NMR.It was foundthat the composition of the teroolymer was influenced by theaddition mode,initial monomer charge ratio,etc.
文摘A new catalyst system was used in the synthesis of polyethylene terephthalate(PET) and its copolymers, which involved a Ln 3+ containing compound. The catalytic effects were studied, and it was found that the direct esterification reaction of terephthalate acid(TPA) with ethylene glycol(EG) can be accelerated by the addition of Ln 3+ containing compound, which acts as a promoter of the catalyst Sb 2O 3 in polycondensation of bis hydroxyethyl terephthalate(BHET).
文摘The catalytic effectsof Ln3+ on synthesis of polyethyleneterephthalate and its copolyesterswere studied. The direct esterification reaction of terephthalate acidwith ethylene glycol can be accelerated hy addition of Ln3+, and theLn3+, compound can be acted aspromoter of Sb2O3 in the stage ofpolycondensation. The mechanismof esterification and polycondensation by addition of Ln3+ was discussed. The thermal-stabilities ofpolyethylene terephthalate and itscopolyesters obtained by addihon ofLn3+ were also investigaed.
基金Project supported by the National Natural Science Foundation of China(21962021)the Yunnan Fundamental Research Projects(202001AU070121)+1 种基金the National Natural Science Foundation of China(51908091)the Special Basic Cooperative Research Programs of Yunnan Provincial Undergraduate Universities'Association(202101BA070001-084)。
文摘In order to analyze the influence of the addition of yttrium and manganese on the soot combustion performance and high temperature stability of CeO_(2) catalyst,a series of Y/Mn-modified CeO_(2) catalysts were prepared.The effects of structural properties,textural properties,oxygen vacancies,Ce^(3+),surface adsorbed oxygen species,reduction properties and desorption properties of oxygen species on the activity were analyzed by various characterization methods.The results of the activity test show that the addition of manganese is beneficial to enhancement of the activity,while the addition of yttrium increases the amount of reactive oxygen species,but decreases the activity.After aging at 700℃,the activity of the CeMn catalyst decreases most sharply,while the catalytic activity of the CeY catalyst can be maintained to a certain extent.Interestingly,the addition of yttrium and manganese at the same time can stabilize the activity.The fundamental reason is that yttrium and manganese move to the surface of the solid solution after aging,which increases the reduction performance of the catalyst,thus contributing to the increase of activity.Although the activity of CeYMn catalyst decreases after aging at 800℃,it is still higher than that of other catalysts aged at 700℃.
基金Project supported by the Global R&D Program of the Korea Foundation for International Cooperation of Science and Technology (KICOS)
文摘C1 chemistry based on synthesis gas, methane, and carbon dioxide offers many routes to industrial chemicals. The reactions related to the synthesis of gas can be classified into direct and indirect approach for making such products, such as acetic acid, dimethyl ether, and alcohol. Catalytic syngas processing is currently done at high temperatures and pressures, conditions that could be unfavorable for the life of the catalyst. Another issue of C1 chemistry is related to the methane-initiated process. It has been known that direct methane conversions are still suffering from low yields and selectivity of products resulting in unprofitable ways to produce products, such as higher hydrocarbons, methanol, and so on. However, many experts and researchers are still trying to find the best method to overcome these barriers, for example, by finding the best catalyst to reduce the high-energy barrier of the reactions and conduct only selective catalyst-surface reactions. The appli- cation of Yttria-Stabilized Zirconia (YSZ) and its combination with other metals for catalyzing purposes are increasing. The existence of an interesting site that acts as oxygen store could be the main reason for it. Moreover, formation of intermediate species on the surface of YSZ also contributes significantly in increasing the production of some specific products. Understanding the phenomena happening inside could be necessary. In this article, the use of YSZ for some C1 chemistry reactions was discussed and reviewed.
基金Project supported by the National Natural Science Foundation of China (20901056)the Natural Science Foundation of Tianjin (11JCYBJC04000)+2 种基金the Program of Introducing Talents to the University Disciplines (B06006)the Program for Changjiang Scholars and Innovative Research Teams in Universities (IRT 0641)Seed Foundation of Tianjin University
文摘Al2O3 and La2O3 layers were coated respectively on a FeCrAl alloy foil by a dip-coating technique and used as the second support for the active LaMnAl11O19 hexaaluminate (HA) phase in a metallic monolithic catalyst. A sample without an intermediate layer was employed for comparison. The properties and performances of the catalyst were examined with X-ray diffraction (XRD), scanning electron microscopy (SEM), ultrasonic vibration and thermal shock techniques. Methane catalytic combustion was performed to evaluate the activity of the catalyst. The results showed that the activity and adhesion of the HA to the alloy foil could be improved with the introduction of the intermediate layer. Al2O3 provided a strong adhesion, while La2O3 weakened the interaction between the active component and alloy foil. For the activity, the catalysts made with the two different intermediate materials also showed difference.
基金Project supported by the National Key Research and Development Program(2017YFC0211003)GM Global Research and Development(GAC 2696)。
文摘The activity and hydrothermal stability of the Rh/Ce_(x)Zr_(1-x)O_(2)(x=0,0.05,0.3,0.5) model three-way catalysts for gasoline vehicle emissions control were investigated in this work.Among the Rh/Ce_(x)Zr_(1-x)O_(2) samples with different Ce/Zr ratios,the Rh/ZrO_(2) sample exhibits a significantly better activity and hydrothermal stability than the rest of the samples.The impacts of having more Ce components in the Rh/Ce_(x)Zr_(1-x)O_(2) catalysts are associated with the strong Rh-O-Ce interaction that tends to over stabilize the rhodium species.A significant amount of such rhodium atoms can be found in the bulk of the support oxides after a hydrothermal aging at 1050℃ with 10% H_(2)O in air for 12 h.Differently,the sintering of rhodium on the surface of Rh/ZrO_(2) catalysts is the main reason for the catalyst deactivation during the hydrothermal aging.These findings provide an example where high dispersion of supported metal induced by strong metal-support interactions does not necessarily lead to high catalytic activity.
基金the National Natural Science Foundation of China for Youths(21908207)National Key R&D Program of China(2021YFB3503200)+3 种基金the Key R&D project of Shandong Province(2021CXGC010703)China Postdoctoral Science Foundation(2020M670659)Shanxi Province Science Foundation for Youths(201901D211224)Scientific and Technological Innovation Programs of Higher Education Institutions in Shanxi(2019L0575)。
文摘To reveal how cerium stabilizes Cu/SAPO-34 at low-temperature hydrothermal aging,various amounts of cerium were introduced into Cu/SAPO-34 via impregnation method and treated at 70℃with RH 80%for 96 h.Cerium as Ce^(3+)and CeO_(2)nanoparticle is located on the surface of Cu/SAPO-34,and Ce^(3+)plays a vital role on gradually decreasing surface acidity and blocking defect sites with an increase of Ce loading.After hydrothermal aging,Cu/SAPO-34 with high Ce loading shows the superior SCR activity comparable to fresh samples.It is proven that the surface acidity determines the stability of the structure during hydrothermal aging process,and lower surface acidity prevents the number of Cu(Ⅱ)ions from decreasing significantly.Furthermore,the structure's stability helps the recovery of Cu(Ⅱ)ions and renders an outstanding regene ration ability.Our finding paves the way for the design of new Cu/SAPO-34catalysts with good SCR activity and long-term stability in real application.
基金Project supported by National Natural Science Foundation of China(21066008,21266017)Inner Mongolia Science and Technology Plan Project(20101502)
文摘Rare earth-doped copper-manganese mixed oxide catalysts were prepared by coprecipitation and mechanical mixing using copper sulfate, manganese sulfate, and rare-earth oxides REO (REO indicates La2O3, CeO2, Y2O3, or Pr6O11) as raw materials. The samples were characterized by X-ray diffraction (XRD), temperature-programmed reduction (TPR), temperature-programmed reduc-tion of oxidized surfaces (s-TPR), and temperature-programmed desorption (TPD). Catalytic activities were tested for a water-gas shift reaction. Doping rare earth oxides did not alter the crystal structure of the original copper-manganese mixed oxides but changed the interplanar spacing, adsorption performance and reaction performance. Doping with La2O3 enhanced the activity and stability of Cu-Mn mixed oxides because of high copper distribution and fine reduction. Doping with CeO2 and Y2O3 also decreased the reduc-tion temperatures of the samples to different degrees while improving the dispersion of Cu on the surface, thus, catalytic activity was better than that of undoped Cu-Mn sample. The Pr6O11-doped sample was difficult to reduce, the dispersion of surface coppers was lowered, resulting in poor activity.
基金supported by the Program for New Century Excellent Talents in University(NCET-06-0268)Natural Science Foundation of Inner Mongolia(2010ZD03)
文摘Perovskite oxide LaMnO3 was prepared by sol-gel method and the nanosize Au/LaMnO3 catalyst was prepared by deposition-precipitation(DP) method in the paper.Characterization of the catalyst sample was made by X-ray diffractometer(XRD),atom absorption spectra(AAS) and X-ray photoelectron spectroscopy(XPS) instrumental methods.The activity,long-term stability and the reasons for deactivation of the gold catalyst in CO oxidation were investigated.The experiment results demonstrated that the Au/LaMnO3 catalyst exhibited high stability in the ambient storage process.However,the gradual decrease in initial activity during 100 h reaction was still observed,which could be ascribed to the aggregation of gold particles and the transfer from gold ion to the metal gold.
基金Project supported by Natural Science Foundation of Shandong Province(ZR2019MEE112)。
文摘A series of 3DOM CeMnO3 perovskite catalysts were prepared by poly(methyl methacrylate)hardtemplating-excessive impregnation method at calcination temperature of x℃(x=600,700,800)and the heating rate of y℃/min(y=1,2,5,10).The samples were characterized by Brunauer-Emmett-Teller method,scanning electron microscopy,transmission electron microscopy,H2-temperature programmed reduction,X-ray photoelectron spectroscopy,X-ray diffraction,moreover,the effect of the calcination process on the catalytic activity of the samples were discussed by the catalytic combustion of toluene.The results show that the 3DOM CeMnO3 catalysts calcined at 600℃promote the formation of a perovskite structure,inhibit the reduction of the Mn4+species in the catalyst with high temperature.The catalyst expresses the complete macroporous structure,large specific surface area(38.8 m^(2)/g),higher adsorption oxygen concentration and Mn4+substance concentration,with a low T90%=172℃.By preparing the catalysts at different calcination heating rates,it can be concluded that the catalyst possesses a high concentration of adsorbed oxygen and a low reduction temperature and a large specific surface area(40.42 m^(2)/g)greatly promotes adsorption stage catalytic oxidation reaction and catalytic combustion of toluene at low temperature under the heating rate of 5℃/min.When the heating rate is 1℃/min,the catalyst has a complete macroporous structure(>250 nm),which is beneficial to the exchange of macromolecular substances during the catalytic reaction and the catalyst has a high concentration of lattice oxygen suitable for the catalysis of toluene in high temperature flue gas combustion.
基金Project supported by National Natural Science Foundation of China(21173195,21203167)
文摘A series of Pd/La-Al2O3(PLA) catalysts with La-Al2O3(LA) support calcined at different temperatures(500, 700, 900 and 1050 oC) were prepared using an incipient wetness impregnation method. The activity of the fresh and hydrothermally aged PLA catalysts were tested for total oxidation of CO and C3H8. The activity of the fresh PLA catalysts for CO and C3H8 oxidation increased with increasing calcination temperature of the support, while the activities of the aged catalysts declined and became essentially the same. CO chemisorption results revealed that the suppressed activities of the aged catalysts were mainly due to the decline of palladium dispersion. The turnover frequency(TOF) of CO oxidation increased with increasing reduction ability of the catalysts, with a fresh catalyst calcined at 1050 oC having the highest value(0.048 s–1). However, the TOF of C3H8 total oxidation was affected by not only the redox properties of catalysts but also the size of Pd particle, and large Pd particles possessed higher TOF value of C3H8 oxidation, with the highest value(0.125 s–1) being obtained on an aged catalyst calcined at 500 oC.
基金PRIN 2006, "Caratterizzazione spettroscopica e morfologica di Me-POSS eterogeneizzati", MEL Chemicals
文摘CeO2-ZeO2 solid solutions are extensively used as oxygen storage promoters in the current automotive three-way catalysts. High thermal stability of the textural properties is one of the most important requirements for practical application since temperatures up to 1273 K are easily experienced by these materials under real working conditions. In the present paper, we investigated how hydrothermal treatments applied to cakes of doped and undoped ZrO2-rich CeO2-ZrO2 precursors might improve the thermal stability of the final CeO2-ZrO2 solid solution. A rationale was developed that allowed to correlate the morphology of the hydrothermaUy treated cake with the thermal stability at 1273 K of the final product, which did not depend on the composition of the mixed oxides.