In the preparation of catalyst for propylene polymerization, the Mg(OEt) 2 support was activated with ethanol/CO 2 system followed by solidification, and treated with TiCl 4 in the presence of ethylbenzoate as an inte...In the preparation of catalyst for propylene polymerization, the Mg(OEt) 2 support was activated with ethanol/CO 2 system followed by solidification, and treated with TiCl 4 in the presence of ethylbenzoate as an internal donor(ID). The chemical compositions of the activated support and the prepared catalyst were examined in detail. During the dissolution of Mg(OEt) 2 support in ethanol medium with CO 2 bubbling, the structure of support changed to magnesium hydrocarbyl carbonate, (CH 3CH 2O) 2- x Mg(O (C O) OCH 2CH 3) x ( x = 1,2). The content of carbonated CO 2 in the activated support was dependent on the heat treatment in the solidification of support. In the preparation procedure of polymerization catalyst, the activated support was treated with TiCl 4 so that the structure of support was converted to MgCl 2 with the incorporation of ID. The polymerization behavior of the pre-pared catalyst was also studied in the presence of phenyltriethoxysilane as an external donor.展开更多
Hydrolysis of TiCl_(4)solution is capable of preparing microscale TiO_(2)particles.This research studied the synthesis of microscale spherical TiO_(2)powders and the hydrolysis kinetics.The effects of the flow field g...Hydrolysis of TiCl_(4)solution is capable of preparing microscale TiO_(2)particles.This research studied the synthesis of microscale spherical TiO_(2)powders and the hydrolysis kinetics.The effects of the flow field generated by different agitators and baffles in the crystallizer,the initial free acid concentration,the initial equivalent TiO_(2)concentration,and the temperature on the hydrolysis progress and powder morphology were systematically studied.The results show that the flow field in a crystallizer can significantly affect the morphology and particle size of the powders,and the axial flow can improve the sphericity of the powders.The increased free HCl and equivalent TiO_(2)concentrations in the pregnant solution inhibit the forward hydrolysis reaction,prolong the time to reach equilibrium,and reduce the yield.An appropriate temperature matching the compositions of the pregnant solution is crucial for the powder morphology and size.Powders with sizes ranging from around 5 um-40μm can be tuned under controlled flow field,solution compositions,and temperature conditions.In addition,the Cheng and Wunderlich modified Avrami equation was used for the crystallization kinetic modeling.The effects of the free HCl concentration,equivalent TiO_(2)concentration,and hydrolysis temperature are reflected in the reaction rate constant and active nuclei reduction index.Increasing the free HCl and equivalent TiO_(2)concentrations will reduce the reaction rate constant and accelerate the deactivation of the active nuclei,thus increasing the final powder size,while increasing the temperature will lead to the opposite results.展开更多
In a rational chiral molecular design of chalcogenides,optically active thiepin with C_(2)-symmetric chirality was synthesized from commercially available thiophene.Then enatioselective Chalcogeno-Baylis-Hillman react...In a rational chiral molecular design of chalcogenides,optically active thiepin with C_(2)-symmetric chirality was synthesized from commercially available thiophene.Then enatioselective Chalcogeno-Baylis-Hillman reactions of arylaldehydes with methyl vinyl ketone(MVK)and acrylates were investigated in the presence of thiepin-Lewis acid complex.Finally,up to 64%ee was achieved in the presence of 0.2 equiv.of(S)-thiepin at 20℃.展开更多
It is well known that electron transport layer(ETL)plays an indispensable role in the planar heterojunction perovskite solar cells(PSCs).TiO_(2) is widely used as an ETL material due to its excellent transport propert...It is well known that electron transport layer(ETL)plays an indispensable role in the planar heterojunction perovskite solar cells(PSCs).TiO_(2) is widely used as an ETL material due to its excellent transport properties,however,the presence of defects in the TiO_(2) layer diminishes the power conversion efficiency(PCE)of the devices.Herein,we introduce a method of low-temperature TiCl_(4) treatment to deposit a TiOx layer on the surface of TiO_(2) film,which can effectively passivate trap states at the TiO_(2) surface.Moreover,the treating process is optimized to be 30 min using a 40 mM TiCl_(4) aqueous solution.Benefiting from this,we obtain the champion device with the highest PCE of 18.47%,which is mainly due to the reduction of surface defects and the deposition of the well-crystallized perovskite films.Besides,the modified PSCs exhibit an average PCE of 17.59%,which is much better than the control devices.展开更多
文摘In the preparation of catalyst for propylene polymerization, the Mg(OEt) 2 support was activated with ethanol/CO 2 system followed by solidification, and treated with TiCl 4 in the presence of ethylbenzoate as an internal donor(ID). The chemical compositions of the activated support and the prepared catalyst were examined in detail. During the dissolution of Mg(OEt) 2 support in ethanol medium with CO 2 bubbling, the structure of support changed to magnesium hydrocarbyl carbonate, (CH 3CH 2O) 2- x Mg(O (C O) OCH 2CH 3) x ( x = 1,2). The content of carbonated CO 2 in the activated support was dependent on the heat treatment in the solidification of support. In the preparation procedure of polymerization catalyst, the activated support was treated with TiCl 4 so that the structure of support was converted to MgCl 2 with the incorporation of ID. The polymerization behavior of the pre-pared catalyst was also studied in the presence of phenyltriethoxysilane as an external donor.
基金supported by the Key Research Program of the Chinese Academy of Sciences(grant number ZDRWCN-2021-3)the Youth Innovation Promotion Association CAS(grant number 2018065)+1 种基金the National Natural Science Foundation of China(grant number 51771179)the Beijing Natural Science Foundation(grant number 2192056).
文摘Hydrolysis of TiCl_(4)solution is capable of preparing microscale TiO_(2)particles.This research studied the synthesis of microscale spherical TiO_(2)powders and the hydrolysis kinetics.The effects of the flow field generated by different agitators and baffles in the crystallizer,the initial free acid concentration,the initial equivalent TiO_(2)concentration,and the temperature on the hydrolysis progress and powder morphology were systematically studied.The results show that the flow field in a crystallizer can significantly affect the morphology and particle size of the powders,and the axial flow can improve the sphericity of the powders.The increased free HCl and equivalent TiO_(2)concentrations in the pregnant solution inhibit the forward hydrolysis reaction,prolong the time to reach equilibrium,and reduce the yield.An appropriate temperature matching the compositions of the pregnant solution is crucial for the powder morphology and size.Powders with sizes ranging from around 5 um-40μm can be tuned under controlled flow field,solution compositions,and temperature conditions.In addition,the Cheng and Wunderlich modified Avrami equation was used for the crystallization kinetic modeling.The effects of the free HCl concentration,equivalent TiO_(2)concentration,and hydrolysis temperature are reflected in the reaction rate constant and active nuclei reduction index.Increasing the free HCl and equivalent TiO_(2)concentrations will reduce the reaction rate constant and accelerate the deactivation of the active nuclei,thus increasing the final powder size,while increasing the temperature will lead to the opposite results.
基金The work was partially supported by the Science and Technology Commission of Shanghai Municipality(No.12ZR1431100).Support from Prof.Gang Zhao was also greatly appreciated.
文摘In a rational chiral molecular design of chalcogenides,optically active thiepin with C_(2)-symmetric chirality was synthesized from commercially available thiophene.Then enatioselective Chalcogeno-Baylis-Hillman reactions of arylaldehydes with methyl vinyl ketone(MVK)and acrylates were investigated in the presence of thiepin-Lewis acid complex.Finally,up to 64%ee was achieved in the presence of 0.2 equiv.of(S)-thiepin at 20℃.
基金funded by China Postdoctoral Science Foundation under Grant No.2017T100751Natural Science Foundation of Shandong Province under Grant No.ZR2017MF007Shandong Science and Technology Plan Project of Higher Education Institutions under Grant No.J16LA02 and the 111 Project of China(B14040)。
文摘It is well known that electron transport layer(ETL)plays an indispensable role in the planar heterojunction perovskite solar cells(PSCs).TiO_(2) is widely used as an ETL material due to its excellent transport properties,however,the presence of defects in the TiO_(2) layer diminishes the power conversion efficiency(PCE)of the devices.Herein,we introduce a method of low-temperature TiCl_(4) treatment to deposit a TiOx layer on the surface of TiO_(2) film,which can effectively passivate trap states at the TiO_(2) surface.Moreover,the treating process is optimized to be 30 min using a 40 mM TiCl_(4) aqueous solution.Benefiting from this,we obtain the champion device with the highest PCE of 18.47%,which is mainly due to the reduction of surface defects and the deposition of the well-crystallized perovskite films.Besides,the modified PSCs exhibit an average PCE of 17.59%,which is much better than the control devices.
