To stabilize Ru nanoparticles against sintering is an urgent problem in the utilization of Ru-based catalysts for NH3 synthesis.In the present study,we used Ru-containing ZSM-5 as seeds to crystallize ZSM-5,and the re...To stabilize Ru nanoparticles against sintering is an urgent problem in the utilization of Ru-based catalysts for NH3 synthesis.In the present study,we used Ru-containing ZSM-5 as seeds to crystallize ZSM-5,and the resulted Ru@ZSM-5 catalyst is highly resistant against Ru sintering.According to the results of diffuse reflectance infrared fourier transform spectroscopy(DRIFTS)and transmission electron microscopy(TEM)analyses,the average size of Ru nanoparticles is around 3.6 nm,which is smaller than that of Ru/ZSM-5-IWI prepared by incipient wetness impregnation.In NH3 synthesis(N2:H2=1:3)at 400℃and 1 MPa,Ru@ZSM-5 displays a formation rate of 5.84 mmolNH3 gcat^-1 h^-1,which is much higher than that of Ru/ZSM-5-IWI(2.13 mmolNH3 gcat^-1 h^-1).According to the results of TEM,N2-temperatureprogrammed desorption(N2-TPD),X-ray photoelectron spectroscopy(XPS)and X-ray absorption fine structure(XAFS)studies,it is deduced that the superior performance of Ru@ZSM-5 is attributable to the small particle size and the ample existence of metallic Ru0 sites.This method of zeolite encapsulation is a feasible way to stabilize Ru nanoparticles for NH3 synthesis.展开更多
The carbonization process of a sucrose‐RuCl3/SBA‐15composite towards a Ru‐containing ordered mesoporous carbon(Ru‐OMC)catalyst was studied by in situ temperature‐programmed infrared spectroscopy to identify the s...The carbonization process of a sucrose‐RuCl3/SBA‐15composite towards a Ru‐containing ordered mesoporous carbon(Ru‐OMC)catalyst was studied by in situ temperature‐programmed infrared spectroscopy to identify the stabilization role of organic carbon precursors during the formation of highly dispersed Ru nanoparticles.The results show that the formation of metal carbonyl species results in the formation of homogeneously distributed Ru nanoparticles,and the rigid silica support and carbon matrix around the Ru(CO)x complex can significantly avoid the sintering and agglomeration of Ru metal particles during elevated temperature thermal treatment.These results ultimately demonstrate that sucrose plays important roles in the formation of homogeneously distributed Ru nanoparticles in a porous carbon matrix.?2018,Dalian Institute of Chemical Physics,Chinese Academy of Sciences.Published by Elsevier B.V.All rights reserved.展开更多
Construction of two Ru^(Ⅲ)cations and six lacunary Keggin fragments resulted in a novel Ru_(2)W_(12)-cluster{(RuO_(6))_(2)(WO_(3))_(12)(H_(2)O)_(12)}bridged polyoxometalate,NaH_(11)[(RuO_(6))(AsW_(9)O_(33))_(3){(W_(6...Construction of two Ru^(Ⅲ)cations and six lacunary Keggin fragments resulted in a novel Ru_(2)W_(12)-cluster{(RuO_(6))_(2)(WO_(3))_(12)(H_(2)O)_(12)}bridged polyoxometalate,NaH_(11)[(RuO_(6))(AsW_(9)O_(33))_(3){(W_(6)O_(3))(H_(2)O)_(6)}]_(2)53H_(2)O(NaH_(11)·1·53H_(2)O),which represent the largest cluster in all the Ru-containing polyoxometalates.The most interesting characteristic is that the symmetry-related Ru_(2)W_(12)-cluster-based hexamers contain two windmill-shaped[(RuO_(6))(AsW_(9)O_(33))_(3){(W_(6)O_(3))(H_(2)O)_(6)}]trimers or the Ru_(2)W_(12) cluster was tightly wrapped by six segments of B-β-AsW_(9)O_(33).The other remarkable feature is that there have one intriguing cubane structure:which is composed of the Ru(1,2)and W(1,28,50,51,52,53)atoms.The oxygenation reactions of anilines to azoxybenzenes was evaluated when NaH_(11)·1·53H_(2)O served as effective catalyst by probing various reaction.The inherent redox property of oxygen-rich polyoxometalate surfaces and high photocatalytic activity of the Ru-containing metal cluster imbedded in NaH_(11)·1·53H_(2)O provide sufficient driving force for the photocatalytic transformation from anilines to azoxybenzenes.The oxidation of anilines can be realized with higher selectivity to afford various azoxybenzene compounds.The durability test shows that Ru-doping catalyst displays excellent chemical stability during the photocatalytic process.展开更多
基金supported by the National Science Fund for Distinguished Young Scholars of China(21825801)the National Natural Science Foundation of China(21972019,21978051).
文摘To stabilize Ru nanoparticles against sintering is an urgent problem in the utilization of Ru-based catalysts for NH3 synthesis.In the present study,we used Ru-containing ZSM-5 as seeds to crystallize ZSM-5,and the resulted Ru@ZSM-5 catalyst is highly resistant against Ru sintering.According to the results of diffuse reflectance infrared fourier transform spectroscopy(DRIFTS)and transmission electron microscopy(TEM)analyses,the average size of Ru nanoparticles is around 3.6 nm,which is smaller than that of Ru/ZSM-5-IWI prepared by incipient wetness impregnation.In NH3 synthesis(N2:H2=1:3)at 400℃and 1 MPa,Ru@ZSM-5 displays a formation rate of 5.84 mmolNH3 gcat^-1 h^-1,which is much higher than that of Ru/ZSM-5-IWI(2.13 mmolNH3 gcat^-1 h^-1).According to the results of TEM,N2-temperatureprogrammed desorption(N2-TPD),X-ray photoelectron spectroscopy(XPS)and X-ray absorption fine structure(XAFS)studies,it is deduced that the superior performance of Ru@ZSM-5 is attributable to the small particle size and the ample existence of metallic Ru0 sites.This method of zeolite encapsulation is a feasible way to stabilize Ru nanoparticles for NH3 synthesis.
基金supported by the Natural Science Foundation of Zhejiang Province(LY17B030010)~~
文摘The carbonization process of a sucrose‐RuCl3/SBA‐15composite towards a Ru‐containing ordered mesoporous carbon(Ru‐OMC)catalyst was studied by in situ temperature‐programmed infrared spectroscopy to identify the stabilization role of organic carbon precursors during the formation of highly dispersed Ru nanoparticles.The results show that the formation of metal carbonyl species results in the formation of homogeneously distributed Ru nanoparticles,and the rigid silica support and carbon matrix around the Ru(CO)x complex can significantly avoid the sintering and agglomeration of Ru metal particles during elevated temperature thermal treatment.These results ultimately demonstrate that sucrose plays important roles in the formation of homogeneously distributed Ru nanoparticles in a porous carbon matrix.?2018,Dalian Institute of Chemical Physics,Chinese Academy of Sciences.Published by Elsevier B.V.All rights reserved.
基金supported bythe National Natural Science Foundationof China(Nos.22171071,22071044,21771054,21571050)。
文摘Construction of two Ru^(Ⅲ)cations and six lacunary Keggin fragments resulted in a novel Ru_(2)W_(12)-cluster{(RuO_(6))_(2)(WO_(3))_(12)(H_(2)O)_(12)}bridged polyoxometalate,NaH_(11)[(RuO_(6))(AsW_(9)O_(33))_(3){(W_(6)O_(3))(H_(2)O)_(6)}]_(2)53H_(2)O(NaH_(11)·1·53H_(2)O),which represent the largest cluster in all the Ru-containing polyoxometalates.The most interesting characteristic is that the symmetry-related Ru_(2)W_(12)-cluster-based hexamers contain two windmill-shaped[(RuO_(6))(AsW_(9)O_(33))_(3){(W_(6)O_(3))(H_(2)O)_(6)}]trimers or the Ru_(2)W_(12) cluster was tightly wrapped by six segments of B-β-AsW_(9)O_(33).The other remarkable feature is that there have one intriguing cubane structure:which is composed of the Ru(1,2)and W(1,28,50,51,52,53)atoms.The oxygenation reactions of anilines to azoxybenzenes was evaluated when NaH_(11)·1·53H_(2)O served as effective catalyst by probing various reaction.The inherent redox property of oxygen-rich polyoxometalate surfaces and high photocatalytic activity of the Ru-containing metal cluster imbedded in NaH_(11)·1·53H_(2)O provide sufficient driving force for the photocatalytic transformation from anilines to azoxybenzenes.The oxidation of anilines can be realized with higher selectivity to afford various azoxybenzene compounds.The durability test shows that Ru-doping catalyst displays excellent chemical stability during the photocatalytic process.
