Ionic liquids tailored and confined by one-step assembly with mesoporous silica for boosting the catalytic conversion of CO2 into cyclic carbonates
Ionic liquids tailored and confined by one-step assembly with mesoporous silica for boosting the catalytic conversion of CO2 into cyclic carbonates
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通过与介孔二氧化硅一步组装定制和限制的离子液体，用于促进二氧化碳催化转化为环状碳酸酯
DOI：
10.1039/c8gc01038b
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发表时间：
2018-07
期刊：
影响因子：
9.8
通讯作者：
Zhang Suojiang
中科院分区：
文献类型：
--
作者：
Su Qian;Qi Yaqiong;Yao Xiaoqian;Cheng Weiguo;Dong Li;Chen Songsong;Zhang Suojiang
在经济和节能的基础上，采用约束法首次探索了离子液体催化CO2转化为环状碳酸盐的最小有效剂量。以一定量的硅源和不同数量的il为模板一步组装介孔二氧化硅（mSiO2），将一定量的1-乙基-3-甲基咪唑溴化物（EmimBr）裁剪并限定在mSiO2中。在相同的反应条件下，约束型ILs （EmimBr@mSiO2）保留了同相和非均相催化剂的优点，表现出比本体EmimBr更高的性能。在所有制备的材料中，EmimBr添加量最低（6.9 wt%）的EmimBr@mSiO2的催化活性提高最大，TOF达到112.6 h−1，几乎是体相的1.7倍，具有良好的可回收性。催化活性的提高可能是由于介孔比例较大，EmimBr的分散性较好（Si/Br = 25），以及结构中暴露较多的硅醇基团（Si - oh /Br = 8）的协同作用。通过XPS分析和密度泛函理论（DFT）计算，证实了Si-OH的压缩效应可以增强阳离子和阴离子的相互作用，从而在限制较少的il时更牢固地稳定空间中的il。
On the basis of economic and energy-saving criteria, the minimum effective dose of ionic liquids (ILs) for the catalytic conversion of CO2 into cyclic carbonates was first explored by confinement. With one-step assembly of mesoporous silica (mSiO2) by using a fixed amount of silicon source with varying amounts of ILs as templates, certain amounts of 1-ethyl-3-methyl imidazolium bromides (EmimBr) were tailored and confined in mSiO2. The confined ILs (EmimBr@mSiO2) retained the advantages of homo- and heterogeneous catalysts, exhibiting higher performance than bulk EmimBr under identical reaction conditions. Amongst all the prepared materials, EmimBr@mSiO2 with the lowest amount of EmimBr (6.9 wt%) exhibited the biggest improvement in catalytic activity, achieving a TOF of 112.6 h−1 which is almost 1.7 times the bulk phase with good recyclability. The boosted catalytic activity could be attributed to the larger proportion of mesopores, the better dispersity of EmimBr (Si/Br = 25) and the synergistic effect from more exposed silanol groups (Si–OH/Br = 8) in the structure. The good recyclability was then explained by the XPS analysis and density functional theory (DFT) calculation, which confirmed that the compressing effect from Si–OH could enhance the cation and anion interaction to stabilize ILs in the space more firmly when less ILs were confined.