In many sources of volatile organic compounds (VOCs), large amounts of water vapor come from the air and the reactors. The relative humidity (RH) of exhaust gas is normally >60% and is supersaturated. Maintaining t...In many sources of volatile organic compounds (VOCs), large amounts of water vapor come from the air and the reactors. The relative humidity (RH) of exhaust gas is normally >60% and is supersaturated. Maintaining the property of adsorbent on VOCs in a highly humid gas stream is a serious industrial problem. In this study, the adsorption/desorption behavior of toluene in a micro-mesoporous polymeric resin was investigated in a highly humid environment to explore the influence of abound water vapor on resin adsorption and regeneration. This resin could selectively adsorb toluene at an RH of 80%, and its adsorption property was unaffected by the presence of water vapor. In the case of humidity saturation, the resin displayed a high adsorption capacity at a moisture content of <30%. Therefore, the polymer resin is an excellent water-resistant adsorbent of VOCs. In the regenerative experiment, the resin maintained its original adsorption capability after four adsorption/ desorption cycles of toluene purging with nitrogen gas at 120℃. The resin exhibited excellent regeneration performance at high humidity.展开更多
Volatile organic compounds(VOCs)are difficult to be eliminated safely and effectively because of their large concentration fluctuations.Thus,maintaining a stable concentration of VOCs is a significant study.In this re...Volatile organic compounds(VOCs)are difficult to be eliminated safely and effectively because of their large concentration fluctuations.Thus,maintaining a stable concentration of VOCs is a significant study.In this research,H2O,Tween-80,[Emim]BF4,[Emim]PF6,and[Hnmp]HSO4 were applied to absorb and desorb simulated VOCs.The ionic liquid[Emim]BF4 demonstrated the best performance and was thus selected for further experiments.As the ionic liquid acted as a buffer,the toluene concentration with a fluctuation of 2000–20000 mg·m-3 was stabilized at 6000–12000 mg·m-3.Heating distillation(90°C)was highly efficient to recover[Emim]BF4 from toluene.The regenerated[Emim]BF4 could retain its initial absorption capacity even after multiple cycles.Moreover,[Emim]BF4 had the same buffer function on various aromatic hydrocarbons.展开更多
CeO_(2),La_(2)O_(3),and CeO_(2)-Y_(2)O_(3) oxides were coated on the surface of spherical granular AI_(2)O_(3)(3-5 mm)through impregnation method,and proved as better supports of Pd and Pt catalysts.The influences of ...CeO_(2),La_(2)O_(3),and CeO_(2)-Y_(2)O_(3) oxides were coated on the surface of spherical granular AI_(2)O_(3)(3-5 mm)through impregnation method,and proved as better supports of Pd and Pt catalysts.The influences of rare earth metal doping on the adsorption rates of Pd and Pt ions,as well as the catalytic performance,were investigated.Results show that the H_(2)PtCl_(6)·6H_(2)O adsorption rates of the Al_(2)O_(3) carriers modified by Ce,La,and CeY increase significantly.These rare earth coatings can adsorb almost all H2PtCl_(6)·6H_(2)O in the solution.Compared with Pt/Al_(2)O_(3) catalyst,Pt/Ce-AI_(2)O_(3) and Pt/CeY-AI_(2)O_(3) catalysts have better degradation performance for toluene,and the T_(90) temperatures are both about 147℃.According to X-ray photoelectron spectroscopy(XPS)characterization,Pt^(0)is an important active species for catalytic oxidation reaction of toluene.After CeO_(2)modification to the conventional Pt/Al_(2)O_(3)catalyst,the proportion of Pt^(0)increases from 74.5%to 82.1%.When the Pt^(0)content in the metal state is improved,the redox activity of the catalyst is promoted correspondingly.展开更多
The metal oxides CuMnCe and CeY washcoats on cordierite were prepared using an impregnation method, and then used as support for the active Pt component to prepare the Pt/CuMnCe and Pt/CeY monolithic catalysts for the...The metal oxides CuMnCe and CeY washcoats on cordierite were prepared using an impregnation method, and then used as support for the active Pt component to prepare the Pt/CuMnCe and Pt/CeY monolithic catalysts for the deep oxidation of VOCs. In comparison with the Pt/CeY, CuMnCe, and CeY monolithic catalysts, the Pt/CuMnCe monolithic catalyst shows an excellent performance for toluene,ethyl acetate,and n-hexane oxidation and the Tis low to 216, 200 and 260 ℃,respectively. The active components Pt/PtO and CuMnCe result in a better synergetic interaction, which promote the catalyst reducibility, increase the oxygen mobility, and enhance the adsorption and activation of organic molecules.展开更多
A series of Pt-V/Ce-Zr-O diesel oxidation catalysts was prepared using the impregnation method. The catalytic activity and sulfur resistance of Pt-V/Ce-Zr-O were investigated in the presence of simulated diesel exhaus...A series of Pt-V/Ce-Zr-O diesel oxidation catalysts was prepared using the impregnation method. The catalytic activity and sulfur resistance of Pt-V/Ce-Zr-O were investigated in the presence of simulated diesel exhaust. The effect of vanadium on the structure and redox properties of the catalysts was also investigated using the Brunauer-Emmett-Teller method,X-ray diffraction, H2temperature-programmed reduction, CO temperature-programmed desorption, X-ray photoelectron spectroscopy, and Energy Dispersive Spectroscopy. Results showed that the Pt particles were well dispersed on the Ce-Zr-O carrier through the vanadium isolation effect, which significantly improved the oxidation activity toward CO and hydrocarbons. An electron-withdrawing phenomenon occurred from V to Pt, resulting in an increase in the metallic nature of platinum, which was beneficial to hydrocarbon molecular activation.展开更多
Ce-modified Mn-Fe mixed-oxide catalysts were prepared by a citric acid sol-gel method and characterized by X-ray diffraction,Raman,N2 adsorption-desorption,infrared spectra H2 temperature-programmed reduction and ther...Ce-modified Mn-Fe mixed-oxide catalysts were prepared by a citric acid sol-gel method and characterized by X-ray diffraction,Raman,N2 adsorption-desorption,infrared spectra H2 temperature-programmed reduction and thermogravimetric analyses.Their catalytic properties were investigated in ozone(O3)decomposition reaction.Results show that the small amount of rare earth metal Ce added during Mn-Fe(FM) mixed-oxide synthesis greatly improves the catalytic performance in O3 decomposition.Among the prepared catalysts.the C0.04(FM)0.96 mixed-oxide catalyst exhibits the highest catalytic activity and stability.The O3 conversion over C0.04(FM)0.96 is 98% after 24 h reaction at 25℃ under dry condition,and that over FM decreases to 90% after 16 h reaction.At 0℃,the O3 conversion over C0.04(FM)0.96 is 95% after 7 h reaction under dry condition.and that over FM slows down to 70%.Under humid condition(RH 65%),the O3 conversion over C0.04(FM)0.96 is 63% after 6.5 h reaction at 25℃.while that over FM decreases to 55%.When Ce is doped into Mn-Fe mixed oxides,the small amount of Ce enters the crystal lattice of MnO2.and partial Fe is separated to form Fe2O3.This changes cause lattice distortion and increase defects and enable the as-synthesized Ce-Fe-Mn ternary mixed-oxide catalysts to acquire additional oxygen vacancies and increase their specific surface area,thereby increasing the number of reaction sites and enhancing the catalytic performance of the catalysts for O3 decomposition.展开更多
A catalyst based on mixed V-Ni oxides supported on TiO2(Ni-V/TiO2)was obtained using the sol-gel method.Its catalytic performance relative to dichloromethane(DCM)degradation was investigated.Characterization and analy...A catalyst based on mixed V-Ni oxides supported on TiO2(Ni-V/TiO2)was obtained using the sol-gel method.Its catalytic performance relative to dichloromethane(DCM)degradation was investigated.Characterization and analysis were conducted using transmission electron microscopy,H2 temperature-programmed reduction,pyridine-Fourier transform infrared spectroscopy(FTIR)characterization,and X-ray diffraction.Results showed that the original hollow anatase structure of pure TiO2 was well-maintained after Ni-V loading.The loading of NiO-VOx not only significantly improved the stability of pure TiO2 but also inhibited the formation of the by-product monochloromethane(MCM).Among the series of Ni-V/TiO2 catalysts,4%Ni-V/TiO2 possessed the highest catalytic activity,with 90%DCM conversion at only 203℃.No by-products and no significant changes in the catalytic activity were observed during combustion of DCM after 100 hr of a continuous stability test.Furthermore,thermogravimetric analysis(O2-TG)and energy dispersive spectrometer(EDS)characterization of the used 4%Ni-V/TiO2 catalyst revealed that no coke deposition or chlorine species could be detected on the catalyst surface.展开更多
Cu-Mn, Cu-Mn-Ce, and Cu-Ce mixed-oxide catalysts were prepared by a citric acid sol-gel method and then characterized by XRD, BET, H_2-TPR and XPS analyses. Their catalytic properties were investigated in the toluene ...Cu-Mn, Cu-Mn-Ce, and Cu-Ce mixed-oxide catalysts were prepared by a citric acid sol-gel method and then characterized by XRD, BET, H_2-TPR and XPS analyses. Their catalytic properties were investigated in the toluene combustion reaction. Results showed that the Cu-Mn-Ce ternary mixed-oxide catalyst with 1：2：4 mole ratios had the highest catalytic activity, and 99% toluene conversion was achieved at temperatures below 220°C. In the Cu-Mn-Ce catalyst, a portion of Cu and Mn species entered into the Ce O2 fluorite lattice, which led to the formation of a ceria-based solid solution. Excess Cu and Mn oxides existed on the surface of the ceria-based solid solution. The coexistence of Cu-Mn mixed oxides and the ceria-based solid solution resulted in a better synergetic interaction than the Cu-Mn and Cu-Ce catalysts, which promoted catalyst reducibility, increased oxygen mobility, and enhanced the formation of abundant active oxygen species.展开更多
The catalytic oxidation performance toward ethylene oxide(EO)and the consequent mechanism were investigated on the Pt-Ru/CuCeO_(x)bimetallic catalyst,which was prepared by a distinct method combining stepwise adsorpti...The catalytic oxidation performance toward ethylene oxide(EO)and the consequent mechanism were investigated on the Pt-Ru/CuCeO_(x)bimetallic catalyst,which was prepared by a distinct method combining stepwise adsorption and subsequent impregnation.The catalytic tests show that the introduction of Ru into the Pt catalyst,so as to form Pt-Ru bimetallic active sites,can greatly increase the oxidation activity of the catalyst,as evidenced by the extremely lower full oxidation temperature(120℃)when compared with that of the Pt/CeO_(2) catalyst(160℃).The XPS spectra show that the Ru species(mainly RuO_(x))have strong interaction with the CuCeO_(x) support,which can therefore affect the electron transfer between the Pt species and the support.As a result,the oxygen activation on Pt species is obviously facilitated and catalytic activity is enhanced.Finally,in situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTs)was used to track the reaction mechanism.It is found that the catalytic oxidation process follows the MvK catalytic mechanism at low temperature and the L-H catalytic mechanism when the temperature moves to higher range.展开更多
The interaction between Pt and its various supports can regulate the intrinsic electronic structure of Pt particles and their catalytic performance.Herein,Pt/CeO2 and Pt/SiC catalysts were successfully prepared via a ...The interaction between Pt and its various supports can regulate the intrinsic electronic structure of Pt particles and their catalytic performance.Herein,Pt/CeO2 and Pt/SiC catalysts were successfully prepared via a facile Pt colloidal particle deposition method,and their catalytic performance in CO oxidation was investigated.XRD,TEM,XPS and H2-TPR were used to identify the states of Pt particles on the support surface,as well as their effect on the performance of the catalysts.Formation of the Pt-O-Ce interaction is one of the factors controlling catalyst activity.Under the oxidative treatment at low temperature,the Pt-O-Ce interaction plays an important role in improving the catalytic activity.After calcining at high temperature,enhanced Pt-O-Ce interaction results in the absence of metallic Pt0 on the support surface,as evidenced by the appearance of Pt2+species.It is consistent with the XPS data of Pt/CeO2,and is the main reason behind the deactivation of the catalyst.By contrast,either no interaction is formed between Pt and SiC or Pt nanoparticles remain in the metallic Pt0 state on the SiC surface even after aging at 800℃in an oxidizing atmosphere.Thus,the Pt/SiC shows better thermal stability than Pt/CeO2.The interaction between Pt and the active support may be concluded to be essential for CO oxidation at low temperature,but strong interactions may induce serious deactivation of catalytic activity.展开更多
Carbon–silica materials with hierarchical pores consisting of micropores and mesopores were prepared by introducing nanocarbon microspheres derived from biomass sugar into silica gel channels in a hydrothermal enviro...Carbon–silica materials with hierarchical pores consisting of micropores and mesopores were prepared by introducing nanocarbon microspheres derived from biomass sugar into silica gel channels in a hydrothermal environment.The physicochemical properties of the materials were characterized by nitrogen physical adsorption(BET),scanning electron microscopy(SEM),and thermogravimetric(TG),and the adsorption properties of various organic waste gases were investigated.The results showed that microporous carbon materials were introduced successfully into the silica gel channels,thus showing the high adsorption capacity of activated carbon in high humidity organic waste gas,and the high stability and mechanical strength of the silica gel.The dynamic adsorption behavior confirmed that the carbon–silica material had excellent adsorption capacity for different volatile organic compounds(VOCs).Furthermore,the carbon–silica material exhibited excellent desorption characteristics:adsorbed toluene was completely desorbed at 150℃,thereby showing superior regeneration characteristics.Both features were attributed to the formation of hierarchical pores.展开更多
The preparation of highly active supported noble metal catalysts with a low noble metal loading has always been the ultimate goal of researchers working on catalysis.Hydrothermally treated Pt/Al_(2)O_(3)(Pt/Al_(2)O_(3...The preparation of highly active supported noble metal catalysts with a low noble metal loading has always been the ultimate goal of researchers working on catalysis.Hydrothermally treated Pt/Al_(2)O_(3)(Pt/Al_(2)O_(3)-H)exhibits better catalytic activity than that(Pt/Al_(2)O_(3)-C)treated via the conventional calcination approach.At the high space velocity of100,000 m L/(g·hr),the temperature that correspond to 50%toluene conversion(T50)of Pt/Al_(2)O_(3)-H is 115℃ lower than that of Pt/Al_(2)O_(3)-C,and the turnover frequency(TOF)value can reach 0.0756 sec-1.The mechanism by which the hydrothermal approach enhances Pt/Al_(2)O_(3) activity has been investigated.The structure associated with the high catalytic activity of Pt nanoparticles(NPs)can be retained via hydrothermal treatment.Furthermore,the support is transformed to AlO(OH)with numerous surface hydroxyl groups,which in turn can facilitate the adsorption of toluene.And the synergistic effects of Pt NPs and AlO(OH)increases the contents of Pt in oxidation state and active oxygen,which are beneficial for toluene oxidation.展开更多
文摘In many sources of volatile organic compounds (VOCs), large amounts of water vapor come from the air and the reactors. The relative humidity (RH) of exhaust gas is normally >60% and is supersaturated. Maintaining the property of adsorbent on VOCs in a highly humid gas stream is a serious industrial problem. In this study, the adsorption/desorption behavior of toluene in a micro-mesoporous polymeric resin was investigated in a highly humid environment to explore the influence of abound water vapor on resin adsorption and regeneration. This resin could selectively adsorb toluene at an RH of 80%, and its adsorption property was unaffected by the presence of water vapor. In the case of humidity saturation, the resin displayed a high adsorption capacity at a moisture content of <30%. Therefore, the polymer resin is an excellent water-resistant adsorbent of VOCs. In the regenerative experiment, the resin maintained its original adsorption capability after four adsorption/ desorption cycles of toluene purging with nitrogen gas at 120℃. The resin exhibited excellent regeneration performance at high humidity.
基金Supported by the Zhejiang University Students Science and Technology Innovation Activity Plan Funding(No.2018R403078).
文摘Volatile organic compounds(VOCs)are difficult to be eliminated safely and effectively because of their large concentration fluctuations.Thus,maintaining a stable concentration of VOCs is a significant study.In this research,H2O,Tween-80,[Emim]BF4,[Emim]PF6,and[Hnmp]HSO4 were applied to absorb and desorb simulated VOCs.The ionic liquid[Emim]BF4 demonstrated the best performance and was thus selected for further experiments.As the ionic liquid acted as a buffer,the toluene concentration with a fluctuation of 2000–20000 mg·m-3 was stabilized at 6000–12000 mg·m-3.Heating distillation(90°C)was highly efficient to recover[Emim]BF4 from toluene.The regenerated[Emim]BF4 could retain its initial absorption capacity even after multiple cycles.Moreover,[Emim]BF4 had the same buffer function on various aromatic hydrocarbons.
基金supported by the Scientific Research Fund of Zhejiang Provincial Education Department(Y202043197)the National Natural Science Foundation of China(22078294)+1 种基金the Natural Science Foundation of Zhejiang Province(LZ21E080001,LGF20E080018)the Key Laboratory of Environmental Pollution Control Technology Research of Zhejiang Province(2021ZEKL04)。
文摘CeO_(2),La_(2)O_(3),and CeO_(2)-Y_(2)O_(3) oxides were coated on the surface of spherical granular AI_(2)O_(3)(3-5 mm)through impregnation method,and proved as better supports of Pd and Pt catalysts.The influences of rare earth metal doping on the adsorption rates of Pd and Pt ions,as well as the catalytic performance,were investigated.Results show that the H_(2)PtCl_(6)·6H_(2)O adsorption rates of the Al_(2)O_(3) carriers modified by Ce,La,and CeY increase significantly.These rare earth coatings can adsorb almost all H2PtCl_(6)·6H_(2)O in the solution.Compared with Pt/Al_(2)O_(3) catalyst,Pt/Ce-AI_(2)O_(3) and Pt/CeY-AI_(2)O_(3) catalysts have better degradation performance for toluene,and the T_(90) temperatures are both about 147℃.According to X-ray photoelectron spectroscopy(XPS)characterization,Pt^(0)is an important active species for catalytic oxidation reaction of toluene.After CeO_(2)modification to the conventional Pt/Al_(2)O_(3)catalyst,the proportion of Pt^(0)increases from 74.5%to 82.1%.When the Pt^(0)content in the metal state is improved,the redox activity of the catalyst is promoted correspondingly.
基金Project supported by the National Natural Science Foundation of China(21506194,21676255)the Natural Science Foundation of Zhejiang Province(Y16B070011)the Commission of Science and Technology of Zhejiang Province(2017C03007,2017C33106)
文摘The metal oxides CuMnCe and CeY washcoats on cordierite were prepared using an impregnation method, and then used as support for the active Pt component to prepare the Pt/CuMnCe and Pt/CeY monolithic catalysts for the deep oxidation of VOCs. In comparison with the Pt/CeY, CuMnCe, and CeY monolithic catalysts, the Pt/CuMnCe monolithic catalyst shows an excellent performance for toluene,ethyl acetate,and n-hexane oxidation and the Tis low to 216, 200 and 260 ℃,respectively. The active components Pt/PtO and CuMnCe result in a better synergetic interaction, which promote the catalyst reducibility, increase the oxygen mobility, and enhance the adsorption and activation of organic molecules.
基金financial support from the Natural Science Foundation of China (No. 21107096)the Zhejiang Provincial Natural Science Foundation of China (No. Y14E080035)the Commission of Science and Technology of Zhejiang province (No. 2013C03021)
文摘A series of Pt-V/Ce-Zr-O diesel oxidation catalysts was prepared using the impregnation method. The catalytic activity and sulfur resistance of Pt-V/Ce-Zr-O were investigated in the presence of simulated diesel exhaust. The effect of vanadium on the structure and redox properties of the catalysts was also investigated using the Brunauer-Emmett-Teller method,X-ray diffraction, H2temperature-programmed reduction, CO temperature-programmed desorption, X-ray photoelectron spectroscopy, and Energy Dispersive Spectroscopy. Results showed that the Pt particles were well dispersed on the Ce-Zr-O carrier through the vanadium isolation effect, which significantly improved the oxidation activity toward CO and hydrocarbons. An electron-withdrawing phenomenon occurred from V to Pt, resulting in an increase in the metallic nature of platinum, which was beneficial to hydrocarbon molecular activation.
基金supported by the National Natural Science Foundation of China(21506194,21676255)the Natural Science Foundation of Zhejiang Province(Y16B070011)the Commission of Science and Technology of Zhejiang province(2017C03007,2017C33106).
文摘Ce-modified Mn-Fe mixed-oxide catalysts were prepared by a citric acid sol-gel method and characterized by X-ray diffraction,Raman,N2 adsorption-desorption,infrared spectra H2 temperature-programmed reduction and thermogravimetric analyses.Their catalytic properties were investigated in ozone(O3)decomposition reaction.Results show that the small amount of rare earth metal Ce added during Mn-Fe(FM) mixed-oxide synthesis greatly improves the catalytic performance in O3 decomposition.Among the prepared catalysts.the C0.04(FM)0.96 mixed-oxide catalyst exhibits the highest catalytic activity and stability.The O3 conversion over C0.04(FM)0.96 is 98% after 24 h reaction at 25℃ under dry condition,and that over FM decreases to 90% after 16 h reaction.At 0℃,the O3 conversion over C0.04(FM)0.96 is 95% after 7 h reaction under dry condition.and that over FM slows down to 70%.Under humid condition(RH 65%),the O3 conversion over C0.04(FM)0.96 is 63% after 6.5 h reaction at 25℃.while that over FM decreases to 55%.When Ce is doped into Mn-Fe mixed oxides,the small amount of Ce enters the crystal lattice of MnO2.and partial Fe is separated to form Fe2O3.This changes cause lattice distortion and increase defects and enable the as-synthesized Ce-Fe-Mn ternary mixed-oxide catalysts to acquire additional oxygen vacancies and increase their specific surface area,thereby increasing the number of reaction sites and enhancing the catalytic performance of the catalysts for O3 decomposition.
基金supported by the National Natural Science Foundation of China (Nos. 21506194 and 21676255)the Provincial Natural Science Foundation of Zhejiang Province (No. Y16B070025)the Commission of Science and Technology of Zhejiang Province (Nos. 2017C03007 and 2017C33106)
文摘A catalyst based on mixed V-Ni oxides supported on TiO2(Ni-V/TiO2)was obtained using the sol-gel method.Its catalytic performance relative to dichloromethane(DCM)degradation was investigated.Characterization and analysis were conducted using transmission electron microscopy,H2 temperature-programmed reduction,pyridine-Fourier transform infrared spectroscopy(FTIR)characterization,and X-ray diffraction.Results showed that the original hollow anatase structure of pure TiO2 was well-maintained after Ni-V loading.The loading of NiO-VOx not only significantly improved the stability of pure TiO2 but also inhibited the formation of the by-product monochloromethane(MCM).Among the series of Ni-V/TiO2 catalysts,4%Ni-V/TiO2 possessed the highest catalytic activity,with 90%DCM conversion at only 203℃.No by-products and no significant changes in the catalytic activity were observed during combustion of DCM after 100 hr of a continuous stability test.Furthermore,thermogravimetric analysis(O2-TG)and energy dispersive spectrometer(EDS)characterization of the used 4%Ni-V/TiO2 catalyst revealed that no coke deposition or chlorine species could be detected on the catalyst surface.
基金the financial support from the Natural Science Foundation of China (No. 21107096)Zhejiang Provincial Natural Science Foundation of China (No. Y14E080008)+1 种基金the Commission of Science and Technology of Zhejiang province (No. 2013C03021)the Specialized Research Fund for the Doctoral Program of Higher Education (No. 20133317110004)
文摘Cu-Mn, Cu-Mn-Ce, and Cu-Ce mixed-oxide catalysts were prepared by a citric acid sol-gel method and then characterized by XRD, BET, H_2-TPR and XPS analyses. Their catalytic properties were investigated in the toluene combustion reaction. Results showed that the Cu-Mn-Ce ternary mixed-oxide catalyst with 1：2：4 mole ratios had the highest catalytic activity, and 99% toluene conversion was achieved at temperatures below 220°C. In the Cu-Mn-Ce catalyst, a portion of Cu and Mn species entered into the Ce O2 fluorite lattice, which led to the formation of a ceria-based solid solution. Excess Cu and Mn oxides existed on the surface of the ceria-based solid solution. The coexistence of Cu-Mn mixed oxides and the ceria-based solid solution resulted in a better synergetic interaction than the Cu-Mn and Cu-Ce catalysts, which promoted catalyst reducibility, increased oxygen mobility, and enhanced the formation of abundant active oxygen species.
基金Project supported by the National Natural Science Foundation of China(22208300,22078294,21922607)Natural Science Foundation of Zhejiang Province(LZ21E080001,LGF20E080018).
文摘The catalytic oxidation performance toward ethylene oxide(EO)and the consequent mechanism were investigated on the Pt-Ru/CuCeO_(x)bimetallic catalyst,which was prepared by a distinct method combining stepwise adsorption and subsequent impregnation.The catalytic tests show that the introduction of Ru into the Pt catalyst,so as to form Pt-Ru bimetallic active sites,can greatly increase the oxidation activity of the catalyst,as evidenced by the extremely lower full oxidation temperature(120℃)when compared with that of the Pt/CeO_(2) catalyst(160℃).The XPS spectra show that the Ru species(mainly RuO_(x))have strong interaction with the CuCeO_(x) support,which can therefore affect the electron transfer between the Pt species and the support.As a result,the oxygen activation on Pt species is obviously facilitated and catalytic activity is enhanced.Finally,in situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTs)was used to track the reaction mechanism.It is found that the catalytic oxidation process follows the MvK catalytic mechanism at low temperature and the L-H catalytic mechanism when the temperature moves to higher range.
基金Project supported by the National Natural Science Foundation of China(21506194,21676255)the Natural Science Foundation of Zhejiang Province,China(Y16B070025).
文摘The interaction between Pt and its various supports can regulate the intrinsic electronic structure of Pt particles and their catalytic performance.Herein,Pt/CeO2 and Pt/SiC catalysts were successfully prepared via a facile Pt colloidal particle deposition method,and their catalytic performance in CO oxidation was investigated.XRD,TEM,XPS and H2-TPR were used to identify the states of Pt particles on the support surface,as well as their effect on the performance of the catalysts.Formation of the Pt-O-Ce interaction is one of the factors controlling catalyst activity.Under the oxidative treatment at low temperature,the Pt-O-Ce interaction plays an important role in improving the catalytic activity.After calcining at high temperature,enhanced Pt-O-Ce interaction results in the absence of metallic Pt0 on the support surface,as evidenced by the appearance of Pt2+species.It is consistent with the XPS data of Pt/CeO2,and is the main reason behind the deactivation of the catalyst.By contrast,either no interaction is formed between Pt and SiC or Pt nanoparticles remain in the metallic Pt0 state on the SiC surface even after aging at 800℃in an oxidizing atmosphere.Thus,the Pt/SiC shows better thermal stability than Pt/CeO2.The interaction between Pt and the active support may be concluded to be essential for CO oxidation at low temperature,but strong interactions may induce serious deactivation of catalytic activity.
基金supported by the Natural Science Foundation of China(Nos.21506194 and 21676255)Zhejiang Provincial Natural Science Foundation of China(Nos.Y14E080008and Y16B070025)
文摘Carbon–silica materials with hierarchical pores consisting of micropores and mesopores were prepared by introducing nanocarbon microspheres derived from biomass sugar into silica gel channels in a hydrothermal environment.The physicochemical properties of the materials were characterized by nitrogen physical adsorption(BET),scanning electron microscopy(SEM),and thermogravimetric(TG),and the adsorption properties of various organic waste gases were investigated.The results showed that microporous carbon materials were introduced successfully into the silica gel channels,thus showing the high adsorption capacity of activated carbon in high humidity organic waste gas,and the high stability and mechanical strength of the silica gel.The dynamic adsorption behavior confirmed that the carbon–silica material had excellent adsorption capacity for different volatile organic compounds(VOCs).Furthermore,the carbon–silica material exhibited excellent desorption characteristics:adsorbed toluene was completely desorbed at 150℃,thereby showing superior regeneration characteristics.Both features were attributed to the formation of hierarchical pores.
基金supported by the National Natural Science Foundation of China(Nos.21506194,21676255)the Zhejiang Provincial Natural Science Foundation of China(Nos.LZ21E080001,2017C03007,2017C33106)。
文摘The preparation of highly active supported noble metal catalysts with a low noble metal loading has always been the ultimate goal of researchers working on catalysis.Hydrothermally treated Pt/Al_(2)O_(3)(Pt/Al_(2)O_(3)-H)exhibits better catalytic activity than that(Pt/Al_(2)O_(3)-C)treated via the conventional calcination approach.At the high space velocity of100,000 m L/(g·hr),the temperature that correspond to 50%toluene conversion(T50)of Pt/Al_(2)O_(3)-H is 115℃ lower than that of Pt/Al_(2)O_(3)-C,and the turnover frequency(TOF)value can reach 0.0756 sec-1.The mechanism by which the hydrothermal approach enhances Pt/Al_(2)O_(3) activity has been investigated.The structure associated with the high catalytic activity of Pt nanoparticles(NPs)can be retained via hydrothermal treatment.Furthermore,the support is transformed to AlO(OH)with numerous surface hydroxyl groups,which in turn can facilitate the adsorption of toluene.And the synergistic effects of Pt NPs and AlO(OH)increases the contents of Pt in oxidation state and active oxygen,which are beneficial for toluene oxidation.
