Preparation of magnetic Au/MIL-101(Cr)@SiO2@Fe3O4 catalysts and N-methylation reaction mechanism of CO2 with aniline/H2
Preparation of magnetic Au/MIL-101(Cr)@SiO2@Fe3O4 catalysts and N-methylation reaction mechanism of CO2 with aniline/H2
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磁性Au/MIL-101(Cr)@SiO2@Fe3O4催化剂的制备及CO2与苯胺/H2的N-甲基化反应机理
DOI：
10.1016/j.cattod.2022.04.017
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发表时间：
2022-04
期刊：
影响因子：
5.3
通讯作者：
Shengfu Ji
中科院分区：
文献类型：
--
作者：
Zhenzhen Ran;Jianfang Liu;Muhammad Asim Mushtaq;Xinxin Shao;Haodong Liu;Xiaoqian Du;Shan Hou;Shengfu Ji
采用原位生长法制备了MIL-101（Cr）@SiO2@Fe3O4磁性催化载体，在SiO2@Fe3O4核的表面沉积了MIL-101（Cr）壳层。制备了一系列不同Au含量的Au/MIL-101（Cr）@SiO2@Fe3O4磁性核壳催化剂，并采用吸附-还原法将Au纳米粒子（Au NPs）修饰在磁性载体上。采用XRD、FTIR、HRTEM、XPS、N2吸附-脱附、NH3-TPD、CO2-TPD、VSM等手段对催化剂的结构进行了表征，并在高压微反装置上评价了催化剂的N-甲基化反应性能和循环使用性能。对N-甲基化反应的机理进行了深入的研究。结果表明，MIL-101（Cr）壳层的厚度约为120 nm，Au纳米粒子（约3 nm）分散在MIL-101（Cr）的表面和/或孔中。该催化剂对CO2和苯胺/H2的N-甲基化反应具有良好的催化性能。此外，实现了令人难以置信的可回收性能（外部磁体）和不同胺底物的适用性。在优化条件下，2%Au/MIL-101（Cr）@SiO2@Fe3O4催化剂表现出最佳性能，苯胺转化率接近44.0%，N-甲基苯胺和N，N-二甲基苯胺的选择性分别为71.8%和27.6%。反应机理研究表明，H2在Au NPs上吸附活化，CO2在MIL-101（Cr）笼的O2-刘易斯碱位上吸附活化。随后，活化的H原子与活化的CO2反应生成甲酸作为中间产物。最后，甲酸与吸附的苯胺反应，并在Cr 3+刘易斯酸中心上活化，生成N-甲基苯胺和N，N-二甲基苯胺。MIL-101（Cr）催化剂的核壳结构、高比表面积、丰富的活性中心以及Au NPs与酸碱中心之间的协同作用是提高反应选择性的主要原因。
MIL-101(Cr)@SiO2@Fe3O4magnetic catalytic supports were synthesized by the in-situ growth method, where a MIL-101(Cr) shell was deposited on the surface of the SiO2@Fe3O4core. A series of Au/MIL-101(Cr)@SiO2@Fe3O4magnetic core-shell catalysts with different Au contents were prepared and Au nanoparticles (Au NPs) were decorated on the magnetic supports by the impregnation-reduction method. The structure of the as-synthesized catalysts was characterized by XRD, FTIR, HRTEM, XPS, N2adsorption-desorption, NH3-TPD, CO2-TPD, and VSM, etc. The N-methylation reaction performance and recyclability performance of the catalysts were evaluated in a high-pressure microreactor. The mechanism of the N-methylation reaction had been deeply studied. The results indicated that the thickness of the MIL-101(Cr) shell was about 120 nm, and the Au NPs (~3 nm) were dispersed on the surface and/or in the pores of MIL-101(Cr). The catalytic performance for N-methylation of CO2and aniline/H2to N-methylaniline and N,N-dimethylaniline was satisfactory. Moreover, the incredible recyclability performance (external magnet) and applicability of different amine substrates were achieved. Under the optimized conditions, the 2%Au/MIL-101(Cr)@SiO2@Fe3O4catalyst demonstrated the best performance, the aniline conversion nearly 44.0%, the selectivity of N-methylaniline and N,N-dimethylaniline were 71.8% and 27.6%, respectively. The reaction mechanism investigation indicated that, firstly, H2was adsorbed and activated on the Au NPs, and CO2was adsorbed and activated on the O2-Lewis base sites of MIL-101(Cr) cages. Later, the activated H-atoms reacted with the activated CO2to generate the formic acid as an intermediate product. Finally, the formic acid reacted with the adsorbed aniline and activated on the Cr3+Lewis acid sites to produce N-methylaniline and N,N-dimethylaniline. The enhanced selectivity of the reaction might be attributed to the core-shell architecture, high surface area, plentiful active sites, and synergistic interactions between Au NPs and acid-base sites of the MIL-101(Cr) catalyst.
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影响因子：
62.1
作者：
Álvarez A;Bansode A;Urakawa A;Bavykina AV;Wezendonk TA;Makkee M;Gascon J;Kapteijn F
通讯作者：
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影响因子：
3.9
作者：
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作者：
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影响因子：
3.3
作者：
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通讯作者：
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影响因子：
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作者：
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