研究了木素磺酸盐丙 乙氧基化改性产物的表面活性 ,指出了不同结构衍生物表面活性的差异。结果表明 ,LS PO结构的衍生物有较好的润湿性 ;LS PO EO结构产物有较好的乳化性和在水介质中的分散性 ;而LS PO EO PO结构的衍生物在非水介质中...研究了木素磺酸盐丙 乙氧基化改性产物的表面活性 ,指出了不同结构衍生物表面活性的差异。结果表明 ,LS PO结构的衍生物有较好的润湿性 ;LS PO EO结构产物有较好的乳化性和在水介质中的分散性 ;而LS PO EO PO结构的衍生物在非水介质中有很强的分散性能。展开更多
Aim Isolation and structural elucidation of the constituents from the aerialpart of Hypericum perforatum L. Methods Column chromatography and TLC were used to isolate chemicalconstituents. Physico-chemical characteriz...Aim Isolation and structural elucidation of the constituents from the aerialpart of Hypericum perforatum L. Methods Column chromatography and TLC were used to isolate chemicalconstituents. Physico-chemical characterization and spectroscopic analysis were employed forstructural identification. Results Three flavonols were isolated and identified. Conclusion Compound1 is a novel natural product and its structure has been characterized to be 3, 5, 7-trihydroxy-3',4'-isopropyldioxy-flavone.展开更多
Ag‐Cu‐Cl/BaCO3 catalysts with different Cl and Cu loadings, prepared by the reduction deposition impregnation method, were investigated for gas‐phase epoxidation of propylene by molecular oxygen and characterized b...Ag‐Cu‐Cl/BaCO3 catalysts with different Cl and Cu loadings, prepared by the reduction deposition impregnation method, were investigated for gas‐phase epoxidation of propylene by molecular oxygen and characterized by X‐ray diffraction, X‐ray photoelectron spectroscopy and O2 temperatureprogrammed desorption. Ag‐Cu‐Cl/BaCO3 catalyst with 0.036 wt% Cu and 0.060 wt% Cl exhibitedthe highest catalytic performance for gas‐phase epoxidation of propylene by molecular oxygen. Apropylene oxide selectivity of 83.7% and propylene conversion of 1.2% were achieved under thereaction conditions of 20% C3H6‐10% O2‐70% N2, 200 °C, 0.1 MPa and 3000 h?1. Increasing the Clloading allowed Ag to ensemble easier, whereas changing the Cu loading showed little effect on Agcrystallite size. The appropriate Cl loading of Ag‐Cu‐Cl/BaCO3 catalyst can reduce the dissociationadsorption of oxygen to atomic oxygen species leading to the combustion of propylene to CO2, whichbenefits epoxidation of propylene by molecular oxygen. Excessive Cl loading of Ag‐Cu‐Cl/BaCO3catalyst decreases propylene conversion and propylene oxide selectivity remarkably because of Clpoisoning. The appropriate Cu loading of Ag‐Cu‐Cl/BaCO3 catalyst is efficient for the epoxidation ofpropylene by molecular oxygen, and an excess Cu loading decreases propylene oxide selectivitybecause the aggregation of Cu species increases the exposed surfaces of Ag nanoparticles, whichwas shown by slight increases in atomic oxygen species adsorbed. The appropriate loadings of Cu and Cl of Ag‐Cu‐Cl/BaCO3 catalyst are important to strike the balance between molecular oxygen and atomic oxygen species to create a favorable epoxidation of propylene by molecular oxygen.展开更多
The selective hydrogenolysis of glycerol to 1,3-propanediol(1,3-PDO)is an attractive reaction due to the high demand for valorization of huge excess amounts of glycerol supply as well as the important application of 1...The selective hydrogenolysis of glycerol to 1,3-propanediol(1,3-PDO)is an attractive reaction due to the high demand for valorization of huge excess amounts of glycerol supply as well as the important application of 1,3-PDO in polyester industry.Nevertheless,the formation of 1,3-PDO is thermodynamically less favorable than 1,2-PDO,which necessitates the development of efficient catalysts to manipulate the reaction kinetics towards the 1,3-PDO formation.Among others,Pt-W based catalysts have shown promising activities and selectivities of 1,3-PDO although the reaction mechanism is not well addressed at the molecular level.In this short review,we have compared the performances of different Pt-W based catalysts and discussed the key factors influencing the activity and selectivity.Three possible reaction mechanisms have been discussed in terms of the synergy between Pt and WO_x and the origin of acid sites.Finally,the long-term stability of the Pt-W catalysts has been discussed.We hope this review will provide useful information for the development of more efficient catalysts for this important reaction.展开更多
The characteristics of N-propyl-N′-ethoxycarbonyl thiourea（PECTU） were studied in the flotation experiments of chalcopyrite and pyrite compared with butyl xanthate（BX）. The interaction mechanism between mineral a...The characteristics of N-propyl-N′-ethoxycarbonyl thiourea（PECTU） were studied in the flotation experiments of chalcopyrite and pyrite compared with butyl xanthate（BX）. The interaction mechanism between mineral and PECTU was investigated according to zeta potential and electrochemistry measurements in the presence of PECTU. The results proved that PECTU performed a stronger ability to capture chalcopyrite and a better selectivity against pyrite. The zeta potential of chalcopyrite was positively shifted after interacting with PECTU, which indicated that the collector PECTU was obviously adsorbed on chalcopyrite surface. The cyclic voltammetry and Tafel curves results indicated that the oxidation and corrosion rates of chalcopyrite surface were limited in the presence of PECTU, while the effect of PECTU on pyrite in weak alkaline solution can be neglected basically according to the results of zeta potential and electrochemical tests.展开更多
文摘Aim Isolation and structural elucidation of the constituents from the aerialpart of Hypericum perforatum L. Methods Column chromatography and TLC were used to isolate chemicalconstituents. Physico-chemical characterization and spectroscopic analysis were employed forstructural identification. Results Three flavonols were isolated and identified. Conclusion Compound1 is a novel natural product and its structure has been characterized to be 3, 5, 7-trihydroxy-3',4'-isopropyldioxy-flavone.
基金supported by National Basic Research Program of China (2013CB933200)Commission of Science and Technology of Shanghai Municipality (15DZ1205305)~~
文摘Ag‐Cu‐Cl/BaCO3 catalysts with different Cl and Cu loadings, prepared by the reduction deposition impregnation method, were investigated for gas‐phase epoxidation of propylene by molecular oxygen and characterized by X‐ray diffraction, X‐ray photoelectron spectroscopy and O2 temperatureprogrammed desorption. Ag‐Cu‐Cl/BaCO3 catalyst with 0.036 wt% Cu and 0.060 wt% Cl exhibitedthe highest catalytic performance for gas‐phase epoxidation of propylene by molecular oxygen. Apropylene oxide selectivity of 83.7% and propylene conversion of 1.2% were achieved under thereaction conditions of 20% C3H6‐10% O2‐70% N2, 200 °C, 0.1 MPa and 3000 h?1. Increasing the Clloading allowed Ag to ensemble easier, whereas changing the Cu loading showed little effect on Agcrystallite size. The appropriate Cl loading of Ag‐Cu‐Cl/BaCO3 catalyst can reduce the dissociationadsorption of oxygen to atomic oxygen species leading to the combustion of propylene to CO2, whichbenefits epoxidation of propylene by molecular oxygen. Excessive Cl loading of Ag‐Cu‐Cl/BaCO3catalyst decreases propylene conversion and propylene oxide selectivity remarkably because of Clpoisoning. The appropriate Cu loading of Ag‐Cu‐Cl/BaCO3 catalyst is efficient for the epoxidation ofpropylene by molecular oxygen, and an excess Cu loading decreases propylene oxide selectivitybecause the aggregation of Cu species increases the exposed surfaces of Ag nanoparticles, whichwas shown by slight increases in atomic oxygen species adsorbed. The appropriate loadings of Cu and Cl of Ag‐Cu‐Cl/BaCO3 catalyst are important to strike the balance between molecular oxygen and atomic oxygen species to create a favorable epoxidation of propylene by molecular oxygen.
文摘The selective hydrogenolysis of glycerol to 1,3-propanediol(1,3-PDO)is an attractive reaction due to the high demand for valorization of huge excess amounts of glycerol supply as well as the important application of 1,3-PDO in polyester industry.Nevertheless,the formation of 1,3-PDO is thermodynamically less favorable than 1,2-PDO,which necessitates the development of efficient catalysts to manipulate the reaction kinetics towards the 1,3-PDO formation.Among others,Pt-W based catalysts have shown promising activities and selectivities of 1,3-PDO although the reaction mechanism is not well addressed at the molecular level.In this short review,we have compared the performances of different Pt-W based catalysts and discussed the key factors influencing the activity and selectivity.Three possible reaction mechanisms have been discussed in terms of the synergy between Pt and WO_x and the origin of acid sites.Finally,the long-term stability of the Pt-W catalysts has been discussed.We hope this review will provide useful information for the development of more efficient catalysts for this important reaction.
基金Project(51374249)supported by the National Natural Science Foundation of China
文摘The characteristics of N-propyl-N′-ethoxycarbonyl thiourea（PECTU） were studied in the flotation experiments of chalcopyrite and pyrite compared with butyl xanthate（BX）. The interaction mechanism between mineral and PECTU was investigated according to zeta potential and electrochemistry measurements in the presence of PECTU. The results proved that PECTU performed a stronger ability to capture chalcopyrite and a better selectivity against pyrite. The zeta potential of chalcopyrite was positively shifted after interacting with PECTU, which indicated that the collector PECTU was obviously adsorbed on chalcopyrite surface. The cyclic voltammetry and Tafel curves results indicated that the oxidation and corrosion rates of chalcopyrite surface were limited in the presence of PECTU, while the effect of PECTU on pyrite in weak alkaline solution can be neglected basically according to the results of zeta potential and electrochemical tests.
