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
Partial oxidation of methane to formaldehyde and methanol was studied at atmospheric pressure in the temperature range of 700-750 °C using heteropolycompound catalysts （NH4）6HSiMo11FeO40, （NH4）4PMo11FeO39, an...Partial oxidation of methane to formaldehyde and methanol was studied at atmospheric pressure in the temperature range of 700-750 °C using heteropolycompound catalysts （NH4）6HSiMo11FeO40, （NH4）4PMo11FeO39, and H4PMo11VO40, which were prepared and characterized by various analysis techniques such as infrared, visible UV, XRD and DTA. O2 or N2O was used as the oxidizing agent, and the principal products of the reaction were CH3OH, CH2O, CO, CO2, and water. The conversion and the selectivity of products depend strongly on the reaction temperature, the nature of oxidizing agent, and the composition of catalyst.展开更多
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.
文摘Partial oxidation of methane to formaldehyde and methanol was studied at atmospheric pressure in the temperature range of 700-750 °C using heteropolycompound catalysts （NH4）6HSiMo11FeO40, （NH4）4PMo11FeO39, and H4PMo11VO40, which were prepared and characterized by various analysis techniques such as infrared, visible UV, XRD and DTA. O2 or N2O was used as the oxidizing agent, and the principal products of the reaction were CH3OH, CH2O, CO, CO2, and water. The conversion and the selectivity of products depend strongly on the reaction temperature, the nature of oxidizing agent, and the composition of catalyst.
