Hollow CuO-CeO2-ZrO2nano-particles were prepared with supercritical anti-solvent apparatus by using methanol as sol-vent and supercritical carbon dioxide as anti-solvent. Two key factors (i.e., pressure and temperat...Hollow CuO-CeO2-ZrO2nano-particles were prepared with supercritical anti-solvent apparatus by using methanol as sol-vent and supercritical carbon dioxide as anti-solvent. Two key factors (i.e., pressure and temperature) were investigated to explore the effects of catalyst structure and physic-chemical properties (i.e., morphology, reducing property, oxygen storage capacity and specific surface area). The resulting materials were characterized with X-ray diffraction (XRD), high resolution transmission electron micros-copy (HRTEM), Brunauer-Emmett-Teller (BET),hydrogen temperature programmed reduction (H2-TPR) and oxygen storage capac-ity (OSC) measurement, respectively. The experimental results showed that lower temperatures promoted production of hollow struc-ture nano-particulates. The particle morphology also changed significantly, i.e. the solid construction was first transferred to hollow structure then back to solid construction. The optimal conditions for obtaining hollow nano-particles were determined at 45 °C, 18.0–24.0 MPa.展开更多
A novel solid superacid catalyst S2O8^2-/ZrO2-CeO2 was prepared by a coprecipitation method and characterized by means of XRD FTIR, BET, TEM and DSC/TG analysis methods. The results indicated that incorporation of app...A novel solid superacid catalyst S2O8^2-/ZrO2-CeO2 was prepared by a coprecipitation method and characterized by means of XRD FTIR, BET, TEM and DSC/TG analysis methods. The results indicated that incorporation of appropriate amounts of Ce into the catalyst was beneficial to the formation of sole tetragonal ZrO2 and effectively prevented from the formation of monoclinic ZrO〉 and restrained the loss of sulfated species. XRD revealed the presence of tetragonal Ce0.16Zr0.84O2phase in the case of S2O8^2-/ZrO2-CeO2 calcined above 500 ℃. Catalytic activities of S2O8^2-/ZrO2-CeO2 for the esterification of lactic acid with n-butanol was studied. The results showed that the optimum conditions were as follows: calcination temperature of the catalyst 600 ℃, n(lactic acid):n(n-butyl alcohol)=1.0:3.0, w(S2O8^2-/ZrO2- CeO2)=12.0%, reaction temperature 145 ℃, and reaction time 2 h. The esterification efficiency of lactic acid was about 96.6%.展开更多
In this paper,MCM-41 was synthesized by a soft template technique and MCM-41 supported CuO-CeO2 nano-sized catalysts with different Cu/Ce molar ratios were prepared by a deposition-precipitation method.N2 adsorption,H...In this paper,MCM-41 was synthesized by a soft template technique and MCM-41 supported CuO-CeO2 nano-sized catalysts with different Cu/Ce molar ratios were prepared by a deposition-precipitation method.N2 adsorption,HRTEM-EDS,H2-TPR,XPS characterization,as well as catalytic activity and durability tests for the catalytic combustion of chlorobenzene(CB)were conducted to explore the relationship between the structure and catalytic performance of the catalysts.It is revealed that cuCe(6:1)/MCM-41 has the highest activity and can completely catalyze the degradation of CB at 260℃.The reasons for the high activity of the catalysts are as follows:MCM-41,a type of mesoporous material which has large pore size and large specific surface area,is suitable as a catalyst carrier.The average diameter of nano-sized CuO and CeO2 particles is about 3-5 nm and adding CeO2 improves the dispersion of active component CuO,which are highly and evenly dispersed on the surface of MCM-41.Characterization results also explain why MCM-41 supported CuO-CeO2 with appropriate proportion can highly enhance the catalytic activity.The reason is that CeO2 acting as an oxygen-rich material can improve the mobility of oxygen species through continuous redox between Ce4^+and Ce3^+,and improve the catalytic performance of CuO for CB combustion.Besides,CuCe(6:1)/MCM-41 also displays good durability for CB combustion,both in the humid condition and in the presence of benzene,making it a promising catalytic material for the elimination of chlorinated VOCs.展开更多
A series of praseodymium added CeO2(ZrO2)/TiO2 catalysts separately prepared by methods of sol-gel and impregnation were tested for selective catalytic reduction of NO, and characterized by X-ray diffraction (XRD)...A series of praseodymium added CeO2(ZrO2)/TiO2 catalysts separately prepared by methods of sol-gel and impregnation were tested for selective catalytic reduction of NO, and characterized by X-ray diffraction (XRD), N2-brumauer-emmett-teller (N2-BET), NH3-temperature programmed desorption (NH3-TPD), H2-temperature programmed reduction (H2-TPR), PL spectra, Ra-man spectra, electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS), respectively. Influence of prepara-tion method on catalytic performance was studied. Results showed that the influence of Pr addition on catalytic performance of the CeO2(ZrO2)/TiO2 catalysts was different between the sol-gel method and the impregnation method. The Pr addition tended to interact with TiO2 and formed the structure of Ti-O-Pr in the sol-gel method while it was more likely to interact with CeO2 forming the struc-ture of Ce-O-Pr in the impregnation method. The total acid amount and redox properties of the catalysts prepared by sol-gel method decreased with the addition of Pr element, which resulted in decrease of catalytic activity. In contrast, the Pr-added catalyst prepared by impregnation method was found to possess easier reducibility, more total acid amount and higher proportion of Ce3+ species, which was favourable for higher catalytic activity.展开更多
Zr-doped CuO-CeO2 catalysts for CO selective oxidation were designed and prepared by the hydrothermal method and coprecipitation. The experimental samples were characterized by means of N2 adsorption-desorption isothe...Zr-doped CuO-CeO2 catalysts for CO selective oxidation were designed and prepared by the hydrothermal method and coprecipitation. The experimental samples were characterized by means of N2 adsorption-desorption isotherms, powder X-ray diffraction, temperature-programmed reduction and Xray photoelectron spectroscopy. It is observed that the catalyst prepared by hydrothermal method exhibits larger specific surface area, smaller crystalline size and higher dispersion of active components compared with those of the catalyst obtained by coprecipitation. Meanwhile, redox properties of copper oxide are improved significantly and highly dispersed copper species providing CO oxidation sites are present on the surface. Furthermore, adsorptive centers of CO and active oxygen species increase on the copper-ceria interfaces. The Zr-doped CuO-CeO2 catalyst prepared by hydrothermal method possesses superior catalytic activity and selectivity for selective oxidation of CO at low temperature compared with those of the sample prepared by coprecipitation. The temperature corresponding to 50% CO conversion is only 73 ℃ and the temperature span of total CO conversion is expanded from 120 to 160 ℃.展开更多
A series CeO2(ZrO2)/TiO2 catalysts were modified with Er using a sol-gel method.The catalytic activity of the obtained catalysts in the selective catalytic reduction(SCR) of NO with NH3 was investigated to determi...A series CeO2(ZrO2)/TiO2 catalysts were modified with Er using a sol-gel method.The catalytic activity of the obtained catalysts in the selective catalytic reduction(SCR) of NO with NH3 was investigated to determine the appropriate Er dosage.The catalysts were characterized using X-ray diffraction,N2 adsorption,NH3 temperature-programmed desorption,H2 temperature-programmed reduction,photoluminescence spectroscopy,electron paramagnetic resonance spectroscopy,and X-ray photoelectron spectroscopy.The results showed that the optimum Er/Ce molar ratio was 0.10;this catalyst had excellent resistance to catalyst poisoning caused by vapor and sulfur and gave more than 90% NO conversion at 220–395 ℃ and a gas hourly space velocity of 71 400 h^-1.Er incorporation increased the Ti^3+ concentrations,oxygen storage capacities,and oxygen vacancy concentrations of the catalysts,resulting in excellent catalytic performance.Er incorporation also decreased the acid strength and inhibited growth of TiO2 and CeO2 crystal particles,which increased the catalytic activity.The results show that high oxygen vacancy concentrations and oxygen storage capacities,large amounts of Ti^3+,and low acid strengths give excellent SCR activity.展开更多
基金supported by the National Natural Science Foundation of China(20976120)Natural Science Foundation of Tianjin(09JCYBJC06200)
摘要Hollow CuO-CeO2-ZrO2nano-particles were prepared with supercritical anti-solvent apparatus by using methanol as sol-vent and supercritical carbon dioxide as anti-solvent. Two key factors (i.e., pressure and temperature) were investigated to explore the effects of catalyst structure and physic-chemical properties (i.e., morphology, reducing property, oxygen storage capacity and specific surface area). The resulting materials were characterized with X-ray diffraction (XRD), high resolution transmission electron micros-copy (HRTEM), Brunauer-Emmett-Teller (BET),hydrogen temperature programmed reduction (H2-TPR) and oxygen storage capac-ity (OSC) measurement, respectively. The experimental results showed that lower temperatures promoted production of hollow struc-ture nano-particulates. The particle morphology also changed significantly, i.e. the solid construction was first transferred to hollow structure then back to solid construction. The optimal conditions for obtaining hollow nano-particles were determined at 45 °C, 18.0–24.0 MPa.
基金supported by the Science and Technique Foundation of Shaaxi Province of China (2008K07-32)the Foundation of Shaanxi Educa- tional Committee of China (08JK228)the Graduate Innovation Fund of Shaanxi University of Science and Technology
摘要A novel solid superacid catalyst S2O8^2-/ZrO2-CeO2 was prepared by a coprecipitation method and characterized by means of XRD FTIR, BET, TEM and DSC/TG analysis methods. The results indicated that incorporation of appropriate amounts of Ce into the catalyst was beneficial to the formation of sole tetragonal ZrO2 and effectively prevented from the formation of monoclinic ZrO〉 and restrained the loss of sulfated species. XRD revealed the presence of tetragonal Ce0.16Zr0.84O2phase in the case of S2O8^2-/ZrO2-CeO2 calcined above 500 ℃. Catalytic activities of S2O8^2-/ZrO2-CeO2 for the esterification of lactic acid with n-butanol was studied. The results showed that the optimum conditions were as follows: calcination temperature of the catalyst 600 ℃, n(lactic acid):n(n-butyl alcohol)=1.0:3.0, w(S2O8^2-/ZrO2- CeO2)=12.0%, reaction temperature 145 ℃, and reaction time 2 h. The esterification efficiency of lactic acid was about 96.6%.
基金Project supported by the National Natural Science Foundation of China(21577094)Zhejiang Public Welfare Technology Research Project(LGG19B070003)the Foundation of Science and Technology of Shaoxing City(2018C10019)。
摘要In this paper,MCM-41 was synthesized by a soft template technique and MCM-41 supported CuO-CeO2 nano-sized catalysts with different Cu/Ce molar ratios were prepared by a deposition-precipitation method.N2 adsorption,HRTEM-EDS,H2-TPR,XPS characterization,as well as catalytic activity and durability tests for the catalytic combustion of chlorobenzene(CB)were conducted to explore the relationship between the structure and catalytic performance of the catalysts.It is revealed that cuCe(6:1)/MCM-41 has the highest activity and can completely catalyze the degradation of CB at 260℃.The reasons for the high activity of the catalysts are as follows:MCM-41,a type of mesoporous material which has large pore size and large specific surface area,is suitable as a catalyst carrier.The average diameter of nano-sized CuO and CeO2 particles is about 3-5 nm and adding CeO2 improves the dispersion of active component CuO,which are highly and evenly dispersed on the surface of MCM-41.Characterization results also explain why MCM-41 supported CuO-CeO2 with appropriate proportion can highly enhance the catalytic activity.The reason is that CeO2 acting as an oxygen-rich material can improve the mobility of oxygen species through continuous redox between Ce4^+and Ce3^+,and improve the catalytic performance of CuO for CB combustion.Besides,CuCe(6:1)/MCM-41 also displays good durability for CB combustion,both in the humid condition and in the presence of benzene,making it a promising catalytic material for the elimination of chlorinated VOCs.
基金supported by National Key Research and Development Program of China(2016YFC0205500)National Natural Science Foundation of China(51272105)+1 种基金Jiangsu Provincial Science and Technology Supporting Program(BE2013718)the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
摘要A series of praseodymium added CeO2(ZrO2)/TiO2 catalysts separately prepared by methods of sol-gel and impregnation were tested for selective catalytic reduction of NO, and characterized by X-ray diffraction (XRD), N2-brumauer-emmett-teller (N2-BET), NH3-temperature programmed desorption (NH3-TPD), H2-temperature programmed reduction (H2-TPR), PL spectra, Ra-man spectra, electron paramagnetic resonance (EPR) and X-ray photoelectron spectroscopy (XPS), respectively. Influence of prepara-tion method on catalytic performance was studied. Results showed that the influence of Pr addition on catalytic performance of the CeO2(ZrO2)/TiO2 catalysts was different between the sol-gel method and the impregnation method. The Pr addition tended to interact with TiO2 and formed the structure of Ti-O-Pr in the sol-gel method while it was more likely to interact with CeO2 forming the struc-ture of Ce-O-Pr in the impregnation method. The total acid amount and redox properties of the catalysts prepared by sol-gel method decreased with the addition of Pr element, which resulted in decrease of catalytic activity. In contrast, the Pr-added catalyst prepared by impregnation method was found to possess easier reducibility, more total acid amount and higher proportion of Ce3+ species, which was favourable for higher catalytic activity.
基金Project supported by the National Natural Science Foundation of China(21406174 and 51508435)
摘要Zr-doped CuO-CeO2 catalysts for CO selective oxidation were designed and prepared by the hydrothermal method and coprecipitation. The experimental samples were characterized by means of N2 adsorption-desorption isotherms, powder X-ray diffraction, temperature-programmed reduction and Xray photoelectron spectroscopy. It is observed that the catalyst prepared by hydrothermal method exhibits larger specific surface area, smaller crystalline size and higher dispersion of active components compared with those of the catalyst obtained by coprecipitation. Meanwhile, redox properties of copper oxide are improved significantly and highly dispersed copper species providing CO oxidation sites are present on the surface. Furthermore, adsorptive centers of CO and active oxygen species increase on the copper-ceria interfaces. The Zr-doped CuO-CeO2 catalyst prepared by hydrothermal method possesses superior catalytic activity and selectivity for selective oxidation of CO at low temperature compared with those of the sample prepared by coprecipitation. The temperature corresponding to 50% CO conversion is only 73 ℃ and the temperature span of total CO conversion is expanded from 120 to 160 ℃.
基金supported by the National Natural Science Foundation of China(51272105)Jiangsu Provincial Science and Technology Supporting Program(BE2013718)+1 种基金Research Subject of Environmental Protection Department of Jiangsu Province of China(2013006)Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)~~
摘要A series CeO2(ZrO2)/TiO2 catalysts were modified with Er using a sol-gel method.The catalytic activity of the obtained catalysts in the selective catalytic reduction(SCR) of NO with NH3 was investigated to determine the appropriate Er dosage.The catalysts were characterized using X-ray diffraction,N2 adsorption,NH3 temperature-programmed desorption,H2 temperature-programmed reduction,photoluminescence spectroscopy,electron paramagnetic resonance spectroscopy,and X-ray photoelectron spectroscopy.The results showed that the optimum Er/Ce molar ratio was 0.10;this catalyst had excellent resistance to catalyst poisoning caused by vapor and sulfur and gave more than 90% NO conversion at 220–395 ℃ and a gas hourly space velocity of 71 400 h^-1.Er incorporation increased the Ti^3+ concentrations,oxygen storage capacities,and oxygen vacancy concentrations of the catalysts,resulting in excellent catalytic performance.Er incorporation also decreased the acid strength and inhibited growth of TiO2 and CeO2 crystal particles,which increased the catalytic activity.The results show that high oxygen vacancy concentrations and oxygen storage capacities,large amounts of Ti^3+,and low acid strengths give excellent SCR activity.