CuCl-based catalysts are the most commonly used catalysts for the“direct synthesis”of trimethoxysilane(M3).CuCl species are sensitive to air and water,and are prone to oxidation deactivation.When CuCl is directly us...CuCl-based catalysts are the most commonly used catalysts for the“direct synthesis”of trimethoxysilane(M3).CuCl species are sensitive to air and water,and are prone to oxidation deactivation.When CuCl is directly used as a catalyst,it needs to be purified before the utilization,and the operating conditions for the catalyst preparation are relatively harsh,requiring the inert gas environment.Considering a high-temperature activation step required for CuCl-based catalysts used for catalyzing synthesis of M3 to form active phase Cu–Si alloys(Cu_(x)Si)with Si powder,in this work,a series of catalysts for the“direct synthesis”of M3 were obtained by a one-step high-temperature activation of the mixture of stable CuCl_(2) precursors,activated carbon-reducing agent,and Si powder,simultaneously achieving the reduction of CuCl_(2) to CuCl and the formation of active phase Cu_(x)Si alloys of CuCl with Si powder.The prepared samples were characterized through various characterization techniques,and investigated for the catalytic performance for the“direct synthesis”of M3.Moreover,the operation conditions were optimized,including the activation temperature,catalyst dosage,Si powder particle size,and reaction temperature.The characterization results indicate that during the one-step activation process,the CuCl_(2) precursor is reduced to CuCl,and the resulting CuCl simultaneously reacts with Si powder to form active phases Cu3Si and Cu15Si4 alloys.The optimal catalyst Sacm(250,0.8:10)exhibits a good catalytic activity with selectivity of 95%and yield of 77%for M3,and shows a good universality for various alcohol substrates.Furthermore,the catalytic mechanism of the prepared catalyst for the“direct synthesis”of M3 was discussed.展开更多
Silane coupling regent （3-mercaptopropyl trimethoxysilane （MPTS）） was prepared on the single-crystal silicon substrate to form 2-dimensional self-assembled monolayers （SAMs）. The growth behavior of SAMs formed f...Silane coupling regent （3-mercaptopropyl trimethoxysilane （MPTS）） was prepared on the single-crystal silicon substrate to form 2-dimensional self-assembled monolayers （SAMs）. The growth behavior of SAMs formed from 3-MPTS was investigated using atomic force microscopy （AFM）, contact angle measurements, ellipsometry, and X-ray photoelectron spectroscopy （XPS）. The formation behavior of MPTS SAMs was investigated by a series of AFM images and the roughness of MPTS SAMs on silicon substrates with the assembling time from 1 min to 24 h. The water contact angle measurements indicated the growth behavior of MPTS that correlated with the AFM measurements at different immersion times, too. The chemical states of the typical elements in the MPTS SAMs were analyzed using X-ray photoelectron spectroscopy. The results show that MPTS is self-assembled on the substrate.展开更多
γ-(2,3-Epoxypropoxy)trimethoxysilane is a crucial silicone product synthesized by hydrosilylation.Its derived downstream silicone products have galvanized the development of silicone industry.However,the Speier's...γ-(2,3-Epoxypropoxy)trimethoxysilane is a crucial silicone product synthesized by hydrosilylation.Its derived downstream silicone products have galvanized the development of silicone industry.However,the Speier's or Karstedt's catalysts commonly utilized in its industrial process are homogeneous,leading to complications,such as low catalytic selectivity and recycling difficulty.Herein,a new heterogeneous platinum catalyst was developed by using a titanium-based metal organic framework(MIL-125)composite with polylactic acid(PAA)as the support.The as-synthesized Pt/PAA-2@MIL-125 catalyst exhibited impressive catalytic performance,producing a 97%yield inβ-product,and maintained recyclability for the synthesis ofγ-(2,3-epoxypropoxy)trimethoxysilane.Further characterization analyses revealed that the introduction of PAA resulted in the formation of a defective mesoporous MIL-125,which accelerated the transmission efficiency of reactants.Moreover,the abundant carboxylic acid groups in the MIL-125/PAA composite could interact strongly with Pt active species,thereby enhancing the catalytic performance and minimizing the loss of Pt,ultimately improving its cycling performance.The comprehensive experiments demonstrated the potential of this catalyst as an effective and versatile heterogeneous catalyst not only for the hydrosilylation of various olefins,but also for the hydrosilyation of silanes.展开更多
文摘CuCl-based catalysts are the most commonly used catalysts for the“direct synthesis”of trimethoxysilane(M3).CuCl species are sensitive to air and water,and are prone to oxidation deactivation.When CuCl is directly used as a catalyst,it needs to be purified before the utilization,and the operating conditions for the catalyst preparation are relatively harsh,requiring the inert gas environment.Considering a high-temperature activation step required for CuCl-based catalysts used for catalyzing synthesis of M3 to form active phase Cu–Si alloys(Cu_(x)Si)with Si powder,in this work,a series of catalysts for the“direct synthesis”of M3 were obtained by a one-step high-temperature activation of the mixture of stable CuCl_(2) precursors,activated carbon-reducing agent,and Si powder,simultaneously achieving the reduction of CuCl_(2) to CuCl and the formation of active phase Cu_(x)Si alloys of CuCl with Si powder.The prepared samples were characterized through various characterization techniques,and investigated for the catalytic performance for the“direct synthesis”of M3.Moreover,the operation conditions were optimized,including the activation temperature,catalyst dosage,Si powder particle size,and reaction temperature.The characterization results indicate that during the one-step activation process,the CuCl_(2) precursor is reduced to CuCl,and the resulting CuCl simultaneously reacts with Si powder to form active phases Cu3Si and Cu15Si4 alloys.The optimal catalyst Sacm(250,0.8:10)exhibits a good catalytic activity with selectivity of 95%and yield of 77%for M3,and shows a good universality for various alcohol substrates.Furthermore,the catalytic mechanism of the prepared catalyst for the“direct synthesis”of M3 was discussed.
基金This work was financially supported by the National Natural Science Foundation of China (No.50475023)the Nano Foundation of Shanghai Technology Committee (No.0252nm014)the State Key Laboratory Fund (No.0102) in State Key Laboratory for Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Science
文摘Silane coupling regent （3-mercaptopropyl trimethoxysilane （MPTS）） was prepared on the single-crystal silicon substrate to form 2-dimensional self-assembled monolayers （SAMs）. The growth behavior of SAMs formed from 3-MPTS was investigated using atomic force microscopy （AFM）, contact angle measurements, ellipsometry, and X-ray photoelectron spectroscopy （XPS）. The formation behavior of MPTS SAMs was investigated by a series of AFM images and the roughness of MPTS SAMs on silicon substrates with the assembling time from 1 min to 24 h. The water contact angle measurements indicated the growth behavior of MPTS that correlated with the AFM measurements at different immersion times, too. The chemical states of the typical elements in the MPTS SAMs were analyzed using X-ray photoelectron spectroscopy. The results show that MPTS is self-assembled on the substrate.
基金supported by the National Natural Science Foundation of China(Nos.22262023,22261032,21961021)the Natural Science Foundation of Jiangxi Province,China(No.20202ACB203001)the Fund of Key Laboratory of Nanchang City,China(No.2021NCZDSY-005).
文摘γ-(2,3-Epoxypropoxy)trimethoxysilane is a crucial silicone product synthesized by hydrosilylation.Its derived downstream silicone products have galvanized the development of silicone industry.However,the Speier's or Karstedt's catalysts commonly utilized in its industrial process are homogeneous,leading to complications,such as low catalytic selectivity and recycling difficulty.Herein,a new heterogeneous platinum catalyst was developed by using a titanium-based metal organic framework(MIL-125)composite with polylactic acid(PAA)as the support.The as-synthesized Pt/PAA-2@MIL-125 catalyst exhibited impressive catalytic performance,producing a 97%yield inβ-product,and maintained recyclability for the synthesis ofγ-(2,3-epoxypropoxy)trimethoxysilane.Further characterization analyses revealed that the introduction of PAA resulted in the formation of a defective mesoporous MIL-125,which accelerated the transmission efficiency of reactants.Moreover,the abundant carboxylic acid groups in the MIL-125/PAA composite could interact strongly with Pt active species,thereby enhancing the catalytic performance and minimizing the loss of Pt,ultimately improving its cycling performance.The comprehensive experiments demonstrated the potential of this catalyst as an effective and versatile heterogeneous catalyst not only for the hydrosilylation of various olefins,but also for the hydrosilyation of silanes.
