A highly active sulfided NiPMo/MCM-41(NiPMo-S/M41)hydrodesulfurization(HDS)catalyst was successfully synthesized using Keggin-type phosphomolybdic acid as the phosphorus and molybdenum source and thioacetamide as the ...A highly active sulfided NiPMo/MCM-41(NiPMo-S/M41)hydrodesulfurization(HDS)catalyst was successfully synthesized using Keggin-type phosphomolybdic acid as the phosphorus and molybdenum source and thioacetamide as the sulfur source.The supported catalysts NiPMo/M41,Ni_(2)P-Mo/M41,and Ni_(2)P/M41 were also prepared to investigate the effects of Mo,S,and the Keggin structure on the HDS performance.The HDS activities of NiPMo/M41 and NiPMo-S/M41 toward dibenzothiophene were much higher than that of Ni_(2)P-Mo/M41,demonstrating that the active phases in the Keggin-structured catalysts were significantly superior to the Mo-modified Ni_(2)P phase.The HDS activities of the catalysts followed the order NiPMo-S/M41(96.7%)>NiPMo/M41(89.9%)>Ni_(2)P-Mo/M41(53.5%)>Ni_(2)P/M41(48.9%).For Ni_(2)P/M41,Ni_(2)P-Mo/M41,and NiPMo/M41,cyclohexylbenzene(CHB)was formed in low concentrations(<21.0%),indicating that direct desulfurization was the favored reaction route and that this did not change for Keggin-structured NiPMo/M41.By contrast,the CHB selectivity of NiPMo-S/M41 increased to 44.6%,much higher than that of NiPMo/M41(17.6%),demonstrating that sulfidation enhanced the hydrogenation ability,which was ascribed to a metal-acid synergistic effect.展开更多
Four polyoxometalate complexes, (CPFX·HCl)_3H_4SiW_~12 O_~40 , (CPFX·HCl)_3H_3PW_~12 O_~40 , (CPFX·HCl)_3H_3PMo_~12 O_~40 and (CPFX·HCl)_4H_4SiMo_~12 O_~40 , were prepared from ciprofloxacin hydroc...Four polyoxometalate complexes, (CPFX·HCl)_3H_4SiW_~12 O_~40 , (CPFX·HCl)_3H_3PW_~12 O_~40 , (CPFX·HCl)_3H_3PMo_~12 O_~40 and (CPFX·HCl)_4H_4SiMo_~12 O_~40 , were prepared from ciprofloxacin hydrochloride(CPFX·HCl) reacting with H_nXM_~12 O_~40 ·nH_2O(X=P,Si; M=W,Mo) in an aqueous solution, and characterized by elemental analysis, IR spectrometry and TG-DTA. The IR spectrum confirms the presence of Keggin-type anions of heteropoly acids and the characteristic functional groups of ciprofloxacin. The TG/DTA curves show that their thermal decomposition is a multi-step process including simultaneous collapse of the Keggin-type structure. At first, these compounds had a mass loss of water molecules, then several other mass losses occured due to the decomposition of ciprofloxacin hydrochloride and its fragments with the degradation of Keggin anions. The end product of decomposition is the mixture of WO_3(or MoO_3) and SiO_2(or P_2O_5), identified by X-ray diffraction and IR spectroscopy. The possible thermal decomposition mechanisms of these complexes are proposed. This study exemplified that the thermal stability of the complexes containing tungsten is much better than that of the complexes containing molybdenum.展开更多
Two unusual complexes [Cda（Do）4（H2O）2CI]（PW12O4O）＇2H2O （1） and [Aga（Do）6（PW12O40）][Ag（Do）2]2（PW12O4O）＇2H2O （2） were hydrothermally synthesized by the combination of two different metallic salts, Ke...Two unusual complexes [Cda（Do）4（H2O）2CI]（PW12O4O）＇2H2O （1） and [Aga（Do）6（PW12O40）][Ag（Do）2]2（PW12O4O）＇2H2O （2） were hydrothermally synthesized by the combination of two different metallic salts, Keggin-type polyoxometalate and 1,10-phen-5,6-dione （Do）, and characterized by elemental analyses, inductively coupled plasma analyses, infrared spectra, X-ray photoelectron spectroscopy, thermal gravimetry, photoluminescent spectra and single-crystal X-ray diffraction analyses. Crystal 1 is of monoclinic, space group P21/n with a = 12.383（3）, b = 18.326（4）, c = 16.437（3） A, β = 90.29（3）°, V = 3730.1（13） A3, Z = 2, CdzCasH32NsC1052PW12, Mr. = 4050.24, Dc = 3.604 g＇cm-3,μ（MoKa） = 19.145 mm1, F（000） = 3608, GOOF = 1.168, the final R = 0.0569 and wR = 0.0745 for 5715 observed reflections （1 〉 2σ（I））. Crystal 2 is of triclinic, space group Pi with a = 13.959（5）, b = 16.972（5）, c = 17.647（5）A, α = 85.970（5）, β = 81.353（5）, γ = 86.316（5）°, V = 4117（2） A3 Z = 1, Ag6C120H64N200102P2W24, Mr. = 8539.47, Dc = 3.444 g-cm-3,μ（MoKa） = 17.511 mm-1, F（000） = 3828, GOOF = 1.033, the final R = 0.0981 and wR = 0.1658 for 9906 observed reflections （I 〉 2σ（I））. Structural analyses show that complex 1 has a zero dimensional structure, which is further assembled into a one-dimensional ladder-like structure through hydrogen bonds. Complex 2 possesses a one-dimensional chain structure. Furthermore, solid-state luminescent spectra of complexes 1 and 2 indicate red and green fluorescent emission, respectively.展开更多
Four rare earth inorganic-organic hybrid compounds based on Keggin-type polyoxometalate {SiW_(12)}with general formula [{RE(DMF)_(4)(H_(2)O)_4RE(DMF)_(6)}_(2){SiW_(12)O_(40)}_(3)](RE = La(1),Pr(2),Sm(3),Eu(4),DMF=N,N-...Four rare earth inorganic-organic hybrid compounds based on Keggin-type polyoxometalate {SiW_(12)}with general formula [{RE(DMF)_(4)(H_(2)O)_4RE(DMF)_(6)}_(2){SiW_(12)O_(40)}_(3)](RE = La(1),Pr(2),Sm(3),Eu(4),DMF=N,N-dimethylformamide) were synthesized by the conventional solution method.Structure analyses indicate that four compounds are isostructural and are all built from three [SiW_(12)O_(40)]^(4-) polyoxoanions and DMF ligands linked by RE^(3+).Compounds 1-4 are extremely sensitive to UV light and present excellent photochromic properties,in which the coloring and fading time of samples are both no more than 2 min,and the reversible coloring-fading process can be repeated for at least 10 cycles with little fatigue,suggesting that compounds 1-4 can be a series of fast-responsive and durable photochromic materials.Moreover,the solid-state photoluminescence spectra of compounds 3(Sm) and 4(Eu)display strong characteristic emissions of rare earth ions based on f-f transitions.Meanwhile,compound4(Eu) has a longer fluorescence lifetime up to 566.74 μs.Notably,co mpounds 3(Sm) and 4(Eu) exhibit the switchable luminescence behavior induced by photochromism,which allows them to be used as potential molecular switches.展开更多
A series of NH_4Cs_(1.5)Fe_(0.08)H_xPVMo_(11)As_aO_y heteropolycompoundcatalysts for the selective oxidation of isobutane, having Keggin structure, were synthesized byusing co-precipitation method. The catalysts were ...A series of NH_4Cs_(1.5)Fe_(0.08)H_xPVMo_(11)As_aO_y heteropolycompoundcatalysts for the selective oxidation of isobutane, having Keggin structure, were synthesized byusing co-precipitation method. The catalysts were characterized by FT-IR, H_2-TPR, TG-DTA, SEM andXRD. Effects of the As content, reaction time, reaction temperature and molar ratio of isobutane tooxygen in feedstock on the activity and selectivity of the catalyst were investigated. Theactivation energy of the catalysts was measured by kinetics researches. Results showed theintroduction of Cs^+ into the catalysts shortened the stable period of them and enhanced theircatalytic activity for the selective oxidation of isobutane. The highest conversion of isobutane andthe total selectivity to liquid products were 18.6% and 81.2%, respectively, which were obtained at380℃ with a space velocity of 975 h^(-1) over the NH_4Cs_(1.5)Fe_(0.08)H_xPVMo_(11) As_(0.3)O_yheteropolycompound catalyst. It is confirmed that completely oxidized products were controlled well.展开更多
Seven transition metal molybdovanadoarsenic heteropoly compounds have been synthesized and characterize d using IR,UV,TG-DTA,pH potential ti tration techniques￡(r)The molecular f ormulae of these compounds are pro-po...Seven transition metal molybdovanadoarsenic heteropoly compounds have been synthesized and characterize d using IR,UV,TG-DTA,pH potential ti tration techniques￡(r)The molecular f ormulae of these compounds are pro-posed to be HxMyAsMO10V2O40·zH2 O￡¨x￡1/21?￡3￡?y￡1/2￡±￡?￡2￡?M￡1/2Cr￡?Mn￡?Fe￡?Co￡?Ni￡?Cu￡?Zn￡(c)￡(r)They are all keggin structure￡(r)Surface nature of these compounds have been investigated by temperature programmed desorption and temperature programmed reducti on techniques￡(r)NH 3 -TPD results show that in TPD profile s of the compounds there are two desorption peaks corre sponding to weak acid sites of desorp tion,respectively￡(r)Desorbing activativon energy and preexponential factor of weak acid site of desorption for comp ounds have been calculated￡(r)H2 -TPR re-sults show that introducting transtion metal to molybdovanarsenic acid,the reduction peak temperatures of H2 -TPR shift regularly with increasing d electron numbers of transition metals￡(r)In addition,Zn and Cu heteropoly com-pounds have yet apparent effect of hydrogen spill over￡(r)展开更多
The Cs0.1Cu0.2HXPVAs0.2Mo10Oy and Fe0.12HXPVAs0.3Mo11Oy catalysts were prepared by impregnation method and characterized by FT-IR and TPR.The propane oxidation on the catalysts were carried out in a continuous flow fi...The Cs0.1Cu0.2HXPVAs0.2Mo10Oy and Fe0.12HXPVAs0.3Mo11Oy catalysts were prepared by impregnation method and characterized by FT-IR and TPR.The propane oxidation on the catalysts were carried out in a continuous flow fixed-bed reactor.The result indicated that,under the conditions:V（N2）∶V（O2）∶V（C3H8）=2.2∶3.6∶1.2 θ=440℃,the catalysts performed in activity to a certain extent:over the catalyst of Cs0.1Cu0.2HXPVAs0.2Mo10Oy,the conversion for propane reach 72.92%,with a selectivity of 6.01% to acrylic acid and 2.91% to acetic acid;over Fe0.12HXPVAs0.3Mo11Oy catalyst,the conversion for propane was only 35.56%,but the selectivity for acrylic was as high as 12.15%,and acetic acid was 18.62%.The result showes that Cu could improve the conversion of propane,but could not inhibit the total oxidation product effectively,while Fe could enhance the selectivity for acrylic and acetic acid,but could not improve the conversion for propane.展开更多
基金National Natural Science Foundation of China(Grant No.52006225).
文摘A highly active sulfided NiPMo/MCM-41(NiPMo-S/M41)hydrodesulfurization(HDS)catalyst was successfully synthesized using Keggin-type phosphomolybdic acid as the phosphorus and molybdenum source and thioacetamide as the sulfur source.The supported catalysts NiPMo/M41,Ni_(2)P-Mo/M41,and Ni_(2)P/M41 were also prepared to investigate the effects of Mo,S,and the Keggin structure on the HDS performance.The HDS activities of NiPMo/M41 and NiPMo-S/M41 toward dibenzothiophene were much higher than that of Ni_(2)P-Mo/M41,demonstrating that the active phases in the Keggin-structured catalysts were significantly superior to the Mo-modified Ni_(2)P phase.The HDS activities of the catalysts followed the order NiPMo-S/M41(96.7%)>NiPMo/M41(89.9%)>Ni_(2)P-Mo/M41(53.5%)>Ni_(2)P/M41(48.9%).For Ni_(2)P/M41,Ni_(2)P-Mo/M41,and NiPMo/M41,cyclohexylbenzene(CHB)was formed in low concentrations(<21.0%),indicating that direct desulfurization was the favored reaction route and that this did not change for Keggin-structured NiPMo/M41.By contrast,the CHB selectivity of NiPMo-S/M41 increased to 44.6%,much higher than that of NiPMo/M41(17.6%),demonstrating that sulfidation enhanced the hydrogenation ability,which was ascribed to a metal-acid synergistic effect.
文摘Four polyoxometalate complexes, (CPFX·HCl)_3H_4SiW_~12 O_~40 , (CPFX·HCl)_3H_3PW_~12 O_~40 , (CPFX·HCl)_3H_3PMo_~12 O_~40 and (CPFX·HCl)_4H_4SiMo_~12 O_~40 , were prepared from ciprofloxacin hydrochloride(CPFX·HCl) reacting with H_nXM_~12 O_~40 ·nH_2O(X=P,Si; M=W,Mo) in an aqueous solution, and characterized by elemental analysis, IR spectrometry and TG-DTA. The IR spectrum confirms the presence of Keggin-type anions of heteropoly acids and the characteristic functional groups of ciprofloxacin. The TG/DTA curves show that their thermal decomposition is a multi-step process including simultaneous collapse of the Keggin-type structure. At first, these compounds had a mass loss of water molecules, then several other mass losses occured due to the decomposition of ciprofloxacin hydrochloride and its fragments with the degradation of Keggin anions. The end product of decomposition is the mixture of WO_3(or MoO_3) and SiO_2(or P_2O_5), identified by X-ray diffraction and IR spectroscopy. The possible thermal decomposition mechanisms of these complexes are proposed. This study exemplified that the thermal stability of the complexes containing tungsten is much better than that of the complexes containing molybdenum.
基金Program for New Century Excellent Talents in University(NCET-10-0176)of ChinaNatural Science Foundation Project of Jiangsu University(No.09JDG001,No.11jdg104 and BK2011528)
文摘Two unusual complexes [Cda（Do）4（H2O）2CI]（PW12O4O）＇2H2O （1） and [Aga（Do）6（PW12O40）][Ag（Do）2]2（PW12O4O）＇2H2O （2） were hydrothermally synthesized by the combination of two different metallic salts, Keggin-type polyoxometalate and 1,10-phen-5,6-dione （Do）, and characterized by elemental analyses, inductively coupled plasma analyses, infrared spectra, X-ray photoelectron spectroscopy, thermal gravimetry, photoluminescent spectra and single-crystal X-ray diffraction analyses. Crystal 1 is of monoclinic, space group P21/n with a = 12.383（3）, b = 18.326（4）, c = 16.437（3） A, β = 90.29（3）°, V = 3730.1（13） A3, Z = 2, CdzCasH32NsC1052PW12, Mr. = 4050.24, Dc = 3.604 g＇cm-3,μ（MoKa） = 19.145 mm1, F（000） = 3608, GOOF = 1.168, the final R = 0.0569 and wR = 0.0745 for 5715 observed reflections （1 〉 2σ（I））. Crystal 2 is of triclinic, space group Pi with a = 13.959（5）, b = 16.972（5）, c = 17.647（5）A, α = 85.970（5）, β = 81.353（5）, γ = 86.316（5）°, V = 4117（2） A3 Z = 1, Ag6C120H64N200102P2W24, Mr. = 8539.47, Dc = 3.444 g-cm-3,μ（MoKa） = 17.511 mm-1, F（000） = 3828, GOOF = 1.033, the final R = 0.0981 and wR = 0.1658 for 9906 observed reflections （I 〉 2σ（I））. Structural analyses show that complex 1 has a zero dimensional structure, which is further assembled into a one-dimensional ladder-like structure through hydrogen bonds. Complex 2 possesses a one-dimensional chain structure. Furthermore, solid-state luminescent spectra of complexes 1 and 2 indicate red and green fluorescent emission, respectively.
基金Project supported by the National Natural Science Foundation of China(22172022,21872021,21671033,21901135)。
文摘Four rare earth inorganic-organic hybrid compounds based on Keggin-type polyoxometalate {SiW_(12)}with general formula [{RE(DMF)_(4)(H_(2)O)_4RE(DMF)_(6)}_(2){SiW_(12)O_(40)}_(3)](RE = La(1),Pr(2),Sm(3),Eu(4),DMF=N,N-dimethylformamide) were synthesized by the conventional solution method.Structure analyses indicate that four compounds are isostructural and are all built from three [SiW_(12)O_(40)]^(4-) polyoxoanions and DMF ligands linked by RE^(3+).Compounds 1-4 are extremely sensitive to UV light and present excellent photochromic properties,in which the coloring and fading time of samples are both no more than 2 min,and the reversible coloring-fading process can be repeated for at least 10 cycles with little fatigue,suggesting that compounds 1-4 can be a series of fast-responsive and durable photochromic materials.Moreover,the solid-state photoluminescence spectra of compounds 3(Sm) and 4(Eu)display strong characteristic emissions of rare earth ions based on f-f transitions.Meanwhile,compound4(Eu) has a longer fluorescence lifetime up to 566.74 μs.Notably,co mpounds 3(Sm) and 4(Eu) exhibit the switchable luminescence behavior induced by photochromism,which allows them to be used as potential molecular switches.
基金Supported by Scientific Research Fund of Hunnan Provincial Education Department (03C515) Hunan Provincial Natural Science Foundation of China (04jj6003)
文摘A series of NH_4Cs_(1.5)Fe_(0.08)H_xPVMo_(11)As_aO_y heteropolycompoundcatalysts for the selective oxidation of isobutane, having Keggin structure, were synthesized byusing co-precipitation method. The catalysts were characterized by FT-IR, H_2-TPR, TG-DTA, SEM andXRD. Effects of the As content, reaction time, reaction temperature and molar ratio of isobutane tooxygen in feedstock on the activity and selectivity of the catalyst were investigated. Theactivation energy of the catalysts was measured by kinetics researches. Results showed theintroduction of Cs^+ into the catalysts shortened the stable period of them and enhanced theircatalytic activity for the selective oxidation of isobutane. The highest conversion of isobutane andthe total selectivity to liquid products were 18.6% and 81.2%, respectively, which were obtained at380℃ with a space velocity of 975 h^(-1) over the NH_4Cs_(1.5)Fe_(0.08)H_xPVMo_(11) As_(0.3)O_yheteropolycompound catalyst. It is confirmed that completely oxidized products were controlled well.
文摘Seven transition metal molybdovanadoarsenic heteropoly compounds have been synthesized and characterize d using IR,UV,TG-DTA,pH potential ti tration techniques￡(r)The molecular f ormulae of these compounds are pro-posed to be HxMyAsMO10V2O40·zH2 O￡¨x￡1/21?￡3￡?y￡1/2￡±￡?￡2￡?M￡1/2Cr￡?Mn￡?Fe￡?Co￡?Ni￡?Cu￡?Zn￡(c)￡(r)They are all keggin structure￡(r)Surface nature of these compounds have been investigated by temperature programmed desorption and temperature programmed reducti on techniques￡(r)NH 3 -TPD results show that in TPD profile s of the compounds there are two desorption peaks corre sponding to weak acid sites of desorp tion,respectively￡(r)Desorbing activativon energy and preexponential factor of weak acid site of desorption for comp ounds have been calculated￡(r)H2 -TPR re-sults show that introducting transtion metal to molybdovanarsenic acid,the reduction peak temperatures of H2 -TPR shift regularly with increasing d electron numbers of transition metals￡(r)In addition,Zn and Cu heteropoly com-pounds have yet apparent effect of hydrogen spill over￡(r)
文摘The Cs0.1Cu0.2HXPVAs0.2Mo10Oy and Fe0.12HXPVAs0.3Mo11Oy catalysts were prepared by impregnation method and characterized by FT-IR and TPR.The propane oxidation on the catalysts were carried out in a continuous flow fixed-bed reactor.The result indicated that,under the conditions:V（N2）∶V（O2）∶V（C3H8）=2.2∶3.6∶1.2 θ=440℃,the catalysts performed in activity to a certain extent:over the catalyst of Cs0.1Cu0.2HXPVAs0.2Mo10Oy,the conversion for propane reach 72.92%,with a selectivity of 6.01% to acrylic acid and 2.91% to acetic acid;over Fe0.12HXPVAs0.3Mo11Oy catalyst,the conversion for propane was only 35.56%,but the selectivity for acrylic was as high as 12.15%,and acetic acid was 18.62%.The result showes that Cu could improve the conversion of propane,but could not inhibit the total oxidation product effectively,while Fe could enhance the selectivity for acrylic and acetic acid,but could not improve the conversion for propane.
