(CH_3C_5H_4)Zr(S_2CNBz_2)_3, Mr=987.55, space group P1, a=13.002(4), b=13.659(3), c=29.685(8); α=100.72(2)~o,β=97.23(2)~o, γ=105.36(2)~o; V=4909(2)~3, Z=4, Dc=1.34gcm^(-3), Mo-K(λ=0.71073A) radiation, μ=5.0cm^(-1...(CH_3C_5H_4)Zr(S_2CNBz_2)_3, Mr=987.55, space group P1, a=13.002(4), b=13.659(3), c=29.685(8); α=100.72(2)~o,β=97.23(2)~o, γ=105.36(2)~o; V=4909(2)~3, Z=4, Dc=1.34gcm^(-3), Mo-K(λ=0.71073A) radiation, μ=5.0cm^(-1), R=0.069, Rw=0.078 for 6100 reflections. The title complex has pentagonal bipyramid configuration in which the zirconium atom is coordinated by one CH_3C_5H_4 group and three bidentate dibenzyldithiocarbamate ligands.展开更多
The liquid phase ring-opening of octamethylcy-clotetrasiloxane （D4） was investigated over Pt-H2SO4/Zr- montmorillonite catalyst. Montmorillonite （Mt）, Zr-Mt, H2SO4/Mt, H2SO4/Zr-Mt and Pt-H2SO4/Zr-Mt were also dete...The liquid phase ring-opening of octamethylcy-clotetrasiloxane （D4） was investigated over Pt-H2SO4/Zr- montmorillonite catalyst. Montmorillonite （Mt）, Zr-Mt, H2SO4/Mt, H2SO4/Zr-Mt and Pt-H2SO4/Zr-Mt were also detected for evaluation. The catalysts were characterized by X-ray fluorescence, X-ray diffraction, nitrogen adsorption-desorption, NH3-TPD and pyridine-FTIR measurements. In comparison to activate clay which is used in the industry of catalyst, Zr-Mt catalyst displayed stronger acidity and more excellent catalytic activity in the polymerization of D4, polymethylhydrosiloxane （DH） and hexamethyldisiloxane （MM） to low-hydro sili- cone oil. Relative to Zr-Mt, the acidity of H2SO4/Zr-Mt was noticeably improved and the catalyst exhibited a higher capability of ring-opening of D4 conversion and yield of low-hydro silicone oil. To enhance the stability of H2SO4/Zr-Mt catalyst, a small amount of metals （Pt） was doped. The nitrogen adsorption-desorption results indicated that pore textural parameters of the Pt-H2SO4/Zr-Mt had not changed with larger specific surface area. Compared with H2SO4/Zr-Mt, the total acidity of Pt-H2SO4-Zr/Mt catalyst retained, but the content of the Bransted acid increased and the content of the Lewis acid decreased. The Pt-H2SO4-Zr/Mt catalyst displayed higher catalyst reproducibility. After 40 h reaction of polymerization, the yield of low-hydro silicone oil decreased from 93% to 42% over H2SO4/Zr-Mt catalyst, while the yield of low-hydro silicone oil reduced from 93% to 78% over Pt-H2SO4/Zr-Mt catalyst. A sharp decrease in catalytic activity after 35 h of Pt-H2SO4/Zr-Mt catalyst was detected. Furthermore, Pt-H2SO4/Zr-Mt was completely regenerated under appropriate condition and appeared good repeatability in the D4, DH and MM to low-hydro silicone oil.展开更多
文摘采用光学显微镜和蠕变实验机研究Mg-9Gd-4Y-1Zn-0.5Zr合金在不同温度和应力下的高温蠕变行为。结果表明：在应力为70～130 MPa范围内,200℃时Mg-9Gd-4Y-1Zn-0.5Zr合金的蠕变应力指数n=1.63,蠕变机制为晶界滑动,250℃时蠕变应力指数n=2.63,蠕变机制为位错滑移;在蠕变温度为200～250℃范围内,应力分别为70、90、110和130 MPa时,合金的蠕变激活能Qc分别为108.5、118.9、127.6和134.3 k J/mol;随着温度和应力的增加,合金晶粒长大,合金的蠕变机制由晶界滑动控制转变为位错滑移控制。
文摘(CH_3C_5H_4)Zr(S_2CNBz_2)_3, Mr=987.55, space group P1, a=13.002(4), b=13.659(3), c=29.685(8); α=100.72(2)~o,β=97.23(2)~o, γ=105.36(2)~o; V=4909(2)~3, Z=4, Dc=1.34gcm^(-3), Mo-K(λ=0.71073A) radiation, μ=5.0cm^(-1), R=0.069, Rw=0.078 for 6100 reflections. The title complex has pentagonal bipyramid configuration in which the zirconium atom is coordinated by one CH_3C_5H_4 group and three bidentate dibenzyldithiocarbamate ligands.
基金Supported by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘The liquid phase ring-opening of octamethylcy-clotetrasiloxane （D4） was investigated over Pt-H2SO4/Zr- montmorillonite catalyst. Montmorillonite （Mt）, Zr-Mt, H2SO4/Mt, H2SO4/Zr-Mt and Pt-H2SO4/Zr-Mt were also detected for evaluation. The catalysts were characterized by X-ray fluorescence, X-ray diffraction, nitrogen adsorption-desorption, NH3-TPD and pyridine-FTIR measurements. In comparison to activate clay which is used in the industry of catalyst, Zr-Mt catalyst displayed stronger acidity and more excellent catalytic activity in the polymerization of D4, polymethylhydrosiloxane （DH） and hexamethyldisiloxane （MM） to low-hydro sili- cone oil. Relative to Zr-Mt, the acidity of H2SO4/Zr-Mt was noticeably improved and the catalyst exhibited a higher capability of ring-opening of D4 conversion and yield of low-hydro silicone oil. To enhance the stability of H2SO4/Zr-Mt catalyst, a small amount of metals （Pt） was doped. The nitrogen adsorption-desorption results indicated that pore textural parameters of the Pt-H2SO4/Zr-Mt had not changed with larger specific surface area. Compared with H2SO4/Zr-Mt, the total acidity of Pt-H2SO4-Zr/Mt catalyst retained, but the content of the Bransted acid increased and the content of the Lewis acid decreased. The Pt-H2SO4-Zr/Mt catalyst displayed higher catalyst reproducibility. After 40 h reaction of polymerization, the yield of low-hydro silicone oil decreased from 93% to 42% over H2SO4/Zr-Mt catalyst, while the yield of low-hydro silicone oil reduced from 93% to 78% over Pt-H2SO4/Zr-Mt catalyst. A sharp decrease in catalytic activity after 35 h of Pt-H2SO4/Zr-Mt catalyst was detected. Furthermore, Pt-H2SO4/Zr-Mt was completely regenerated under appropriate condition and appeared good repeatability in the D4, DH and MM to low-hydro silicone oil.
