?β-Unsaturated amides with various substitution pattems at the carbon-carbon double And and nitrogen atom can be reduced to the corresponding saturated amides with high selectivity and yields with NaBH4/BiCl3 system.
The Ru3(CO)12/PEDPA complex was firstly applied in the CO selective reduction of 4-propylthio-2-mitroaniline. The effects of reaction temperature, the pressure of CO and concentration of catalyst on the reduction were...The Ru3(CO)12/PEDPA complex was firstly applied in the CO selective reduction of 4-propylthio-2-mitroaniline. The effects of reaction temperature, the pressure of CO and concentration of catalyst on the reduction were investigated. Under the optimum conditions of T=140℃, Pco=5.0MPa and substrate/catalyst = 300 (molar ratio), the conversion and selectivity were 70% and 98%, respectively. After simple phase separation, the catalyst could be recycled.展开更多
A novel reduction system is reported here in which the compounds with terminal C-C triple bond and disubstituted C-C triple bond react with NaBH4/Pd(PPh3)(4) in a base condition and only terminal C-C triple bond is re...A novel reduction system is reported here in which the compounds with terminal C-C triple bond and disubstituted C-C triple bond react with NaBH4/Pd(PPh3)(4) in a base condition and only terminal C-C triple bond is reduced.展开更多
Three kinds of Ce-based catalysts(CePO_(4),CeVO_(4),Ce_(2)(SO_(4))_(3))were synthesized and used for the selective catalytic reduction(SCR)of NO by NH_(3).NH_(3)-SCR performances were conducted in the temperature rang...Three kinds of Ce-based catalysts(CePO_(4),CeVO_(4),Ce_(2)(SO_(4))_(3))were synthesized and used for the selective catalytic reduction(SCR)of NO by NH_(3).NH_(3)-SCR performances were conducted in the temperature range of 80 to 400°C.The catalytic efficiencies of the three catalysts are as follow:CePO_(4)>CeVO_(4)>Ce_(2)(SO_(4))_(3),which is in agreement with their abilities of NH_(3)adsorption capacities.The highest NO conversion rate of CePO_(4)could reach about 95%,and the catalyst had more than 90%NO conversion rate between 260 and 320°C.The effect of PO_(4)^(3–),VO_(4)^(3–)and SO_(4)^(2–)on NH_(3)-SCR performances of Ce-based catalysts was systematically investigated by the X-ray photoelectron spectroscopy analysis,NH_(3)temperature programmed desorption,H2 temperature programmed reduction and field emission scanning electron microscopy tests.The key factors that can enhance the SCR are the existence of Ce4+,large NH_(3)adsorption capacity,high and early H2 consumptions,and suitable microstructures for gas adsorption.Finally,CePO_(4)and CeVO_(4)catalysts also exhibited relatively strong tolerance of SO2,and the upward trend about 8%was detected due to the sulfation enhancement by SO2 for Ce_(2)(SO_(4))3.展开更多
Nitric oxide(NO_x), as one of the main pollutants, can contribute to a series of environmental problems, and to date the selective catalytic reduction(SCR) of NO_x with NH_3 in the presence of excess of O_2 over the c...Nitric oxide(NO_x), as one of the main pollutants, can contribute to a series of environmental problems, and to date the selective catalytic reduction(SCR) of NO_x with NH_3 in the presence of excess of O_2 over the catalysts has served as one of the most effective methods, in which Mn-based catalysts have been widely studied owing to their excellent low-temperature activity toward NH3-SCR. However, the related structure-activity relation was not satisfactorily explored at the atomic level. By virtue of DFT+U calculations together with microkinetic analysis, we systemically investigate the selective catalytic reduction process of NO with NH_3 over Mn_3 O_4(110), and identify the crucial thermodynamic and kinetic factors that limit the catalytic activity and selectivity.It is found that NH3 prefers to adsorb on the Lewis acid site and then dehydrogenates into NH_2~* assisted by either the two-or three-fold lattice oxygen; NH_2~* would then react with the gaseous NO to form an important intermediate NH_2 NO that prefers to convert into N_2 O rather than N_2 after the sequential dehydrogenation, while the residual H atoms interact with O_2 and left the surface in the form of H_2 O. The rate-determining step is proposed to be the coupling reaction between NH_2~* and gaseous NO.Regarding the complex surface structure of Mn_3 O_4(110),the main active sites are quantitatively revealed to be O_(3 c) and Mn_(4 c).展开更多
The CeO2‐TiO2(CeTi)and CeO2/WO3‐TiO2(CeWTi)catalysts were prepared by a sol‐gel precipitation method and their NH3‐NO/NO2 selective catalytic reduction(SCR)performance was studied.N2O formation and effect of oxyge...The CeO2‐TiO2(CeTi)and CeO2/WO3‐TiO2(CeWTi)catalysts were prepared by a sol‐gel precipitation method and their NH3‐NO/NO2 selective catalytic reduction(SCR)performance was studied.N2O formation and effect of oxygen concentration on SCR performance over CeWTi catalyst were also investigated while varying the NO2/NOx ratio.Results indicate that fast SCR behavior of CeWTi catalyst has the best NH3‐NO/NO2 SCR performance due to the catalyst reoxidation rate by NO2 higher than by O2.Compared with CeTi catalyst,CeWTi catalyst exhibits higher de‐NOx performance under NH3‐NO/NO2 SCR conditions.As the CeTi and CeWTi catalysts exhibit similar redox property,addition of WO3 provides more acid sites which accelerate the reaction between NH4NO3 and NO to get a superior low‐temperature activity.Amount of N2O formation shows a peak at 250 oC mainly derived from NH4NO3 decomposition.展开更多
CdS/graphtic carbon nitride （CdS/g-C3N4） hybrid materials were fabricated by thermal polymerization and hy- drothermal methods using Cd（CH3COO）2-2H2O, thioacetamide, and melamine as precursors. The structural and ...CdS/graphtic carbon nitride （CdS/g-C3N4） hybrid materials were fabricated by thermal polymerization and hy- drothermal methods using Cd（CH3COO）2-2H2O, thioacetamide, and melamine as precursors. The structural and op- tical properties of the as-synthesized samples were investigated by X-ray powder diffraction, UV-Vis diffuse reflec- tance spectroscopy, scanning electron microscopy, transmission electron microscopy, etc. A coupled system toward the selective oxidation of benzyl alcohol to benzaldehyde and the reduction of nitrobenzene into aniline was used to estimate the photocatalytic performance of CdS/g-C3N4 composite photocatalysts under visible light illumination. Results indicate that the CdS/g-C3N4 sample exhibits an outstanding photocatalytic performance for selective oxida- tion of benzyl alcohol and reduction of nitrobenzene. Meanwhile, benzotrifluoride is the best reaction medium among the screened solvents. Further research demonstrates that the selective oxidation of benzyl alcohol to ben- zaldehyde is induced by the photoexcited holes and the reduction of nitrobenzene into aniline is triggered by the photoexcited electrons. Additionally, the catalyst can be recycled several times without noticeable deactivation.展开更多
文摘?β-Unsaturated amides with various substitution pattems at the carbon-carbon double And and nitrogen atom can be reduced to the corresponding saturated amides with high selectivity and yields with NaBH4/BiCl3 system.
文摘The Ru3(CO)12/PEDPA complex was firstly applied in the CO selective reduction of 4-propylthio-2-mitroaniline. The effects of reaction temperature, the pressure of CO and concentration of catalyst on the reduction were investigated. Under the optimum conditions of T=140℃, Pco=5.0MPa and substrate/catalyst = 300 (molar ratio), the conversion and selectivity were 70% and 98%, respectively. After simple phase separation, the catalyst could be recycled.
基金the National Natural Science Foundation of China (No. 29772012)
文摘A novel reduction system is reported here in which the compounds with terminal C-C triple bond and disubstituted C-C triple bond react with NaBH4/Pd(PPh3)(4) in a base condition and only terminal C-C triple bond is reduced.
基金This work was financially supported by the National Natural Science Foundation of China(Grant No.52102367)And the tests of XRD and XPS were supported by Research and Test Center of Materials,Wuhan University of TechnologyDRIFTS,TPD and TPR tests were supported by State Key Laboratory of Silicate Materials for Architectures,Wuhan University of Technology.
文摘Three kinds of Ce-based catalysts(CePO_(4),CeVO_(4),Ce_(2)(SO_(4))_(3))were synthesized and used for the selective catalytic reduction(SCR)of NO by NH_(3).NH_(3)-SCR performances were conducted in the temperature range of 80 to 400°C.The catalytic efficiencies of the three catalysts are as follow:CePO_(4)>CeVO_(4)>Ce_(2)(SO_(4))_(3),which is in agreement with their abilities of NH_(3)adsorption capacities.The highest NO conversion rate of CePO_(4)could reach about 95%,and the catalyst had more than 90%NO conversion rate between 260 and 320°C.The effect of PO_(4)^(3–),VO_(4)^(3–)and SO_(4)^(2–)on NH_(3)-SCR performances of Ce-based catalysts was systematically investigated by the X-ray photoelectron spectroscopy analysis,NH_(3)temperature programmed desorption,H2 temperature programmed reduction and field emission scanning electron microscopy tests.The key factors that can enhance the SCR are the existence of Ce4+,large NH_(3)adsorption capacity,high and early H2 consumptions,and suitable microstructures for gas adsorption.Finally,CePO_(4)and CeVO_(4)catalysts also exhibited relatively strong tolerance of SO2,and the upward trend about 8%was detected due to the sulfation enhancement by SO2 for Ce_(2)(SO_(4))3.
基金supported by the National Natural Science Foundation of China(21333003,21622305)Young Elite Scientist Sponsorship Program by China Association for Science and Technology(YESS20150131)+1 种基金"Shu Guang"project supported by Shanghai Municipal Education Commission and Shanghai Education Development Foundation(13SG30)the Fundamental Research Funds for the Central Universities(WJ616007)
文摘Nitric oxide(NO_x), as one of the main pollutants, can contribute to a series of environmental problems, and to date the selective catalytic reduction(SCR) of NO_x with NH_3 in the presence of excess of O_2 over the catalysts has served as one of the most effective methods, in which Mn-based catalysts have been widely studied owing to their excellent low-temperature activity toward NH3-SCR. However, the related structure-activity relation was not satisfactorily explored at the atomic level. By virtue of DFT+U calculations together with microkinetic analysis, we systemically investigate the selective catalytic reduction process of NO with NH_3 over Mn_3 O_4(110), and identify the crucial thermodynamic and kinetic factors that limit the catalytic activity and selectivity.It is found that NH3 prefers to adsorb on the Lewis acid site and then dehydrogenates into NH_2~* assisted by either the two-or three-fold lattice oxygen; NH_2~* would then react with the gaseous NO to form an important intermediate NH_2 NO that prefers to convert into N_2 O rather than N_2 after the sequential dehydrogenation, while the residual H atoms interact with O_2 and left the surface in the form of H_2 O. The rate-determining step is proposed to be the coupling reaction between NH_2~* and gaseous NO.Regarding the complex surface structure of Mn_3 O_4(110),the main active sites are quantitatively revealed to be O_(3 c) and Mn_(4 c).
基金supported by the National Natural Science Foundation of China(51775296,51375253)~~
文摘The CeO2‐TiO2(CeTi)and CeO2/WO3‐TiO2(CeWTi)catalysts were prepared by a sol‐gel precipitation method and their NH3‐NO/NO2 selective catalytic reduction(SCR)performance was studied.N2O formation and effect of oxygen concentration on SCR performance over CeWTi catalyst were also investigated while varying the NO2/NOx ratio.Results indicate that fast SCR behavior of CeWTi catalyst has the best NH3‐NO/NO2 SCR performance due to the catalyst reoxidation rate by NO2 higher than by O2.Compared with CeTi catalyst,CeWTi catalyst exhibits higher de‐NOx performance under NH3‐NO/NO2 SCR conditions.As the CeTi and CeWTi catalysts exhibit similar redox property,addition of WO3 provides more acid sites which accelerate the reaction between NH4NO3 and NO to get a superior low‐temperature activity.Amount of N2O formation shows a peak at 250 oC mainly derived from NH4NO3 decomposition.
文摘CdS/graphtic carbon nitride （CdS/g-C3N4） hybrid materials were fabricated by thermal polymerization and hy- drothermal methods using Cd（CH3COO）2-2H2O, thioacetamide, and melamine as precursors. The structural and op- tical properties of the as-synthesized samples were investigated by X-ray powder diffraction, UV-Vis diffuse reflec- tance spectroscopy, scanning electron microscopy, transmission electron microscopy, etc. A coupled system toward the selective oxidation of benzyl alcohol to benzaldehyde and the reduction of nitrobenzene into aniline was used to estimate the photocatalytic performance of CdS/g-C3N4 composite photocatalysts under visible light illumination. Results indicate that the CdS/g-C3N4 sample exhibits an outstanding photocatalytic performance for selective oxida- tion of benzyl alcohol and reduction of nitrobenzene. Meanwhile, benzotrifluoride is the best reaction medium among the screened solvents. Further research demonstrates that the selective oxidation of benzyl alcohol to ben- zaldehyde is induced by the photoexcited holes and the reduction of nitrobenzene into aniline is triggered by the photoexcited electrons. Additionally, the catalyst can be recycled several times without noticeable deactivation.
