A modified rare-earth-metal catalyst system combined with quaternary ammonium salts（QASs） as cocatalysts was investigated in the alternating copolymerization of CO_2/propylene oxide（PO） to produce poly（propylene ...A modified rare-earth-metal catalyst system combined with quaternary ammonium salts（QASs） as cocatalysts was investigated in the alternating copolymerization of CO_2/propylene oxide（PO） to produce poly（propylene carbonate）（PPC）. In the presence of ZnO/SiO_2, the ZnEt_2-glycerine-Y（CCl_3OO）_3 catalyst presented higher activity for CO_2/PO copolymerization, as well as a higher molecular weight of polycarbonate, while maintaining the high carbonate content originating from the neat ZnEt_2-glycerine-Y（CCl_3OO）_3 catalyst. In the presence of QASs bearing different halide anions（F., Cl., and Br.）, the type of the halide anion had a strong influence on the activity of the catalyst for CO_2/PO alternating copolymerization. Only tetramethylammonium fluoride（TMAF） could promote the alternating copolymerization without increasing the by-product. Combined the ZnO/SiO_2 catalyst and TMAF, the catalytic activity for CO_2/PO polymerization increased dramatically compared to the basic ternary catalyst system. The improved catalyst system produced a polymer with a high carbonate unit level equivalent to that of the polycarbonate produced by the basic ZnEt_2-glycerine-Y（CCl_3OO）_3 catalyst system.展开更多
The study of the kinetics of gas phase polymerization of butadiene with heterogeneous catalyst based on neodymium(Nd) was carried out.The effects of reaction temperature,reaction pressure,dispersing medium, and types ...The study of the kinetics of gas phase polymerization of butadiene with heterogeneous catalyst based on neodymium(Nd) was carried out.The effects of reaction temperature,reaction pressure,dispersing medium, and types of catalyst on kinetics of polymerization were investigated .A kinetic model with two kinds of active sites was proposed.The results show that the effects of the reaction temperature and the types of dispersing medium and catalyst on the kinetic performance of polymerization are significant,and that the combined model of first and second order decay of active site of catalyst can be used to describe the phenomena.展开更多
The effects of adding rare earth(RE) metals,such as Ce,Yb and Pr to Ni-S_2O_8^(2-)/ZrO_2-Al_2O_3(Ni-SZA) on the structure of catalysts as well as their isomerization performance were studied.The prepared catalysts wer...The effects of adding rare earth(RE) metals,such as Ce,Yb and Pr to Ni-S_2O_8^(2-)/ZrO_2-Al_2O_3(Ni-SZA) on the structure of catalysts as well as their isomerization performance were studied.The prepared catalysts were characterized by XRD,BET,FT-IR,Py-IR,and H_2-TPR,The results showed that the addition of RE metals can increase the strength and amounts of the acid sites,improve the redox properties of catalysts.The Yb-Ni-SZA catalyst showed the best redox properties,which could provide enough metallic sites.In addition,it provided the largest amounts of weak and moderately strong acid sites.Among RE metals modified Ni-SZA catalyst,Yb-Ni-SZA exhibited the highest isopentane yield of 61.7%at 160 °C.The optimum isomerization catalytic performance of the catalysts decreased in the order of Yb-Ni-SZA > Pr-Ni-SZA > Ni-SZA > Ce-Ni-SZA.展开更多
A series of rare-earth metal amides supported by a cyclohexyl-linked bis（β-diketiminato） ligand were synthesized, and theft catalytic activities for hydrophosphonylation of aldehydes and ketones were developed. Rea...A series of rare-earth metal amides supported by a cyclohexyl-linked bis（β-diketiminato） ligand were synthesized, and theft catalytic activities for hydrophosphonylation of aldehydes and ketones were developed. Reaction of [（Me3Si）2N]3RE（ct- C1）Li（THF）3 with the cyclohexyl-linked bis（13-diketimine） H2L （1） （L = Cy[NC（Me）CHC（Me）NAr]2, Cy = cyclohexyl, Ar = 2, 6-i-Pr2C6H3） gave the rare-earth metal amides LREN（SiMe3）2 （RE = Nd（2）, Sin（3）, Dy（4）, Er（5）, Y（6））. All complexes were fully characterized by elemental, spectroscopic and single-crystal X-ray analyses. Investigation of the catalytic properties of the complexes reveals that these complexes exhibited a high catalytic activity towards the hydrophosphonylation of aldehydes and ketones in the presence of a very low loading of rare-earth metal amides （0.1-1 tool%） at room temperature in a short time.展开更多
基金supported by the Pujiang Talent Projects(16PJD016)~~
文摘A modified rare-earth-metal catalyst system combined with quaternary ammonium salts（QASs） as cocatalysts was investigated in the alternating copolymerization of CO_2/propylene oxide（PO） to produce poly（propylene carbonate）（PPC）. In the presence of ZnO/SiO_2, the ZnEt_2-glycerine-Y（CCl_3OO）_3 catalyst presented higher activity for CO_2/PO copolymerization, as well as a higher molecular weight of polycarbonate, while maintaining the high carbonate content originating from the neat ZnEt_2-glycerine-Y（CCl_3OO）_3 catalyst. In the presence of QASs bearing different halide anions（F., Cl., and Br.）, the type of the halide anion had a strong influence on the activity of the catalyst for CO_2/PO alternating copolymerization. Only tetramethylammonium fluoride（TMAF） could promote the alternating copolymerization without increasing the by-product. Combined the ZnO/SiO_2 catalyst and TMAF, the catalytic activity for CO_2/PO polymerization increased dramatically compared to the basic ternary catalyst system. The improved catalyst system produced a polymer with a high carbonate unit level equivalent to that of the polycarbonate produced by the basic ZnEt_2-glycerine-Y（CCl_3OO）_3 catalyst system.
文摘The study of the kinetics of gas phase polymerization of butadiene with heterogeneous catalyst based on neodymium(Nd) was carried out.The effects of reaction temperature,reaction pressure,dispersing medium, and types of catalyst on kinetics of polymerization were investigated .A kinetic model with two kinds of active sites was proposed.The results show that the effects of the reaction temperature and the types of dispersing medium and catalyst on the kinetic performance of polymerization are significant,and that the combined model of first and second order decay of active site of catalyst can be used to describe the phenomena.
基金Supported by the Technology Risk Innovation Foundation of China National Petroleum Corporation(07-06D-01-04-03-02)
文摘The effects of adding rare earth(RE) metals,such as Ce,Yb and Pr to Ni-S_2O_8^(2-)/ZrO_2-Al_2O_3(Ni-SZA) on the structure of catalysts as well as their isomerization performance were studied.The prepared catalysts were characterized by XRD,BET,FT-IR,Py-IR,and H_2-TPR,The results showed that the addition of RE metals can increase the strength and amounts of the acid sites,improve the redox properties of catalysts.The Yb-Ni-SZA catalyst showed the best redox properties,which could provide enough metallic sites.In addition,it provided the largest amounts of weak and moderately strong acid sites.Among RE metals modified Ni-SZA catalyst,Yb-Ni-SZA exhibited the highest isopentane yield of 61.7%at 160 °C.The optimum isomerization catalytic performance of the catalysts decreased in the order of Yb-Ni-SZA > Pr-Ni-SZA > Ni-SZA > Ce-Ni-SZA.
文摘A series of rare-earth metal amides supported by a cyclohexyl-linked bis（β-diketiminato） ligand were synthesized, and theft catalytic activities for hydrophosphonylation of aldehydes and ketones were developed. Reaction of [（Me3Si）2N]3RE（ct- C1）Li（THF）3 with the cyclohexyl-linked bis（13-diketimine） H2L （1） （L = Cy[NC（Me）CHC（Me）NAr]2, Cy = cyclohexyl, Ar = 2, 6-i-Pr2C6H3） gave the rare-earth metal amides LREN（SiMe3）2 （RE = Nd（2）, Sin（3）, Dy（4）, Er（5）, Y（6））. All complexes were fully characterized by elemental, spectroscopic and single-crystal X-ray analyses. Investigation of the catalytic properties of the complexes reveals that these complexes exhibited a high catalytic activity towards the hydrophosphonylation of aldehydes and ketones in the presence of a very low loading of rare-earth metal amides （0.1-1 tool%） at room temperature in a short time.
