In the presence of room temperature ionic liquids based on 1 butyl 3 methylimidazolium salt and butylpyridinium salt, cycloaddition of propylene oxide and carbon dioxide without any additional organic solvents was inv...In the presence of room temperature ionic liquids based on 1 butyl 3 methylimidazolium salt and butylpyridinium salt, cycloaddition of propylene oxide and carbon dioxide without any additional organic solvents was investigated. It was found that both cations and anions of the room temperature ionic liquids have strong influence on the catalytic activity. The better catalytic performance was achieved with 1 butyl 3 methylimidazolium tetrafluoroborate as a catalyst. A suitable CO 2/propylene oxide molar ratio is needed for the reaction, and the conversion of propylene oxide increases with the increase of reaction temperature. The ionic liquid as a catalyst for such reaction can be recycled.展开更多
分别采用尿素法和滴定共沉淀法(包括高过饱和法和低过饱和法)制备了镁铝水滑石,利用 X 射线衍射、傅里叶变换红外光谱、热重-差热分析和扫描电子显微镜等方法对镁铝水滑石进行表征,并考察了不同方法制备的镁铝水滑石催化环氧丙烷与甲醇...分别采用尿素法和滴定共沉淀法(包括高过饱和法和低过饱和法)制备了镁铝水滑石,利用 X 射线衍射、傅里叶变换红外光谱、热重-差热分析和扫描电子显微镜等方法对镁铝水滑石进行表征,并考察了不同方法制备的镁铝水滑石催化环氧丙烷与甲醇进行醚化反应合成丙二醇单甲醚的性能。表征结果显示,尿素法制备的镁铝水滑石结晶度高、晶粒规整均匀。实验结果表明,尿素法制备的镁铝水滑石的催化活性明显好于高过饱和法制备的镁铝水滑石的催化活性,前者在500℃下煅烧6～7 h 后制得的镁铝复合金属氧化物的催化活性更高,可使环氧丙烷转化率达93.8%,丙二醇单甲醚选择性达97.2%,其中丙二醇单甲伯醚的选择性达100.0%。该催化剂使用后无需处理即可重复使用,是一种稳定性好、选择性高的环境友好催化剂。展开更多
In the presence of Dawson-type polyoxotungstate, α 2-[(n-C 4H 9) 4] (11-n)P 2W 17O 61(M n+·Br)[abbreviated as P 2W 17M·Br, M=Co(Ⅱ), Mn(Ⅲ), Cu(Ⅱ)] and saturated [(n-C 4H 9) 4N] 6P 2W 18O 62(abbreviated as...In the presence of Dawson-type polyoxotungstate, α 2-[(n-C 4H 9) 4] (11-n)P 2W 17O 61(M n+·Br)[abbreviated as P 2W 17M·Br, M=Co(Ⅱ), Mn(Ⅲ), Cu(Ⅱ)] and saturated [(n-C 4H 9) 4N] 6P 2W 18O 62(abbreviated as P 2W 18), cycloaddition reaction of carbon dioxide to propylene oxide were studied under moderate reaction conditions without any additional organic solvents. The experimental results indicated that the synthesis of propylene carbonate was completed in 98% yield and 100% selectivity by using {P 2W 17Co·Br} as the catalyst, while the P 2W 18 complex showed the lowest catalytic activity with less than 1% yield of propylene carbonate. The dependency of the catalytic activity on transition metal of mono-substituted polyoxometalate, P 2W 17M·Br, as well as the nucleophilicity of the bromide ion was concluded from the process analysis.展开更多
文摘In the presence of room temperature ionic liquids based on 1 butyl 3 methylimidazolium salt and butylpyridinium salt, cycloaddition of propylene oxide and carbon dioxide without any additional organic solvents was investigated. It was found that both cations and anions of the room temperature ionic liquids have strong influence on the catalytic activity. The better catalytic performance was achieved with 1 butyl 3 methylimidazolium tetrafluoroborate as a catalyst. A suitable CO 2/propylene oxide molar ratio is needed for the reaction, and the conversion of propylene oxide increases with the increase of reaction temperature. The ionic liquid as a catalyst for such reaction can be recycled.
文摘分别采用尿素法和滴定共沉淀法(包括高过饱和法和低过饱和法)制备了镁铝水滑石,利用 X 射线衍射、傅里叶变换红外光谱、热重-差热分析和扫描电子显微镜等方法对镁铝水滑石进行表征,并考察了不同方法制备的镁铝水滑石催化环氧丙烷与甲醇进行醚化反应合成丙二醇单甲醚的性能。表征结果显示,尿素法制备的镁铝水滑石结晶度高、晶粒规整均匀。实验结果表明,尿素法制备的镁铝水滑石的催化活性明显好于高过饱和法制备的镁铝水滑石的催化活性,前者在500℃下煅烧6～7 h 后制得的镁铝复合金属氧化物的催化活性更高,可使环氧丙烷转化率达93.8%,丙二醇单甲醚选择性达97.2%,其中丙二醇单甲伯醚的选择性达100.0%。该催化剂使用后无需处理即可重复使用,是一种稳定性好、选择性高的环境友好催化剂。
文摘In the presence of Dawson-type polyoxotungstate, α 2-[(n-C 4H 9) 4] (11-n)P 2W 17O 61(M n+·Br)[abbreviated as P 2W 17M·Br, M=Co(Ⅱ), Mn(Ⅲ), Cu(Ⅱ)] and saturated [(n-C 4H 9) 4N] 6P 2W 18O 62(abbreviated as P 2W 18), cycloaddition reaction of carbon dioxide to propylene oxide were studied under moderate reaction conditions without any additional organic solvents. The experimental results indicated that the synthesis of propylene carbonate was completed in 98% yield and 100% selectivity by using {P 2W 17Co·Br} as the catalyst, while the P 2W 18 complex showed the lowest catalytic activity with less than 1% yield of propylene carbonate. The dependency of the catalytic activity on transition metal of mono-substituted polyoxometalate, P 2W 17M·Br, as well as the nucleophilicity of the bromide ion was concluded from the process analysis.
