Combined Catalytic Action of Supported Cu and Au in Imine Production from Coupled Benzyl Alcohol and Nitrobenzene Reactions
Combined Catalytic Action of Supported Cu and Au in Imine Production from Coupled Benzyl Alcohol and Nitrobenzene Reactions
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DOI：
10.1016/j.apcata.2018.03.024
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发表时间：
2018-05
影响因子：
5.5
通讯作者：
Maoshuai Li;F. Cárdenas-Lizana;M. Keane
中科院分区：
文献类型：
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作者：
Maoshuai Li;F. Cárdenas-Lizana;M. Keane
已经建立了在 Cu/SiO2 和 (TiO2, MgO) 负载的 Au 催化剂混合物上连续气相耦合苯甲醇脱氢与硝基苯加氢合成亚胺 (N-亚苄基苯胺) 的可行性。通过比表面积、孔体积、TPR、H2化学吸附、STEM、XPS和TGA-DSC分析对催化剂进行了表征。通过沉积-沉淀法制备的Au/TiO2比通过浸渍法制备的Au/MgO（1-15nm，平均值=7.7nm）具有更窄的粒径分布（1-6nm）和更小的平均值（3.2nm）。苯甲醇在 Cu/SiO2 上脱氢（生成苯甲醛）的速率比负载的 Au 高（十倍），并且 Au/TiO2 表现出比 Cu/SiO2 和 Au/MgO 更高的 H2 化学吸附能力和更高（十倍）的硝基苯氢化速率。单独的 Cu/SiO2 上的交叉偶联反应证明氢利用效率低下，并且暂时的活性损失与碳质（苯甲酸盐）沉积有关（基于 XPS 和 TGA-DSC 分析）。 Au/TiO2（和Au/MgO）与Cu/SiO2 的结合提高了亚胺的形成速率和H2 的利用效率。 Au/TiO2 与 Cu/SiO2 的组合可以避免 Cu/SiO2 失活，从而提高了稳定性，在 Cu/Au=10 时亚胺产量增加了四倍，并且氢气得到充分利用。
The feasibility of continuous gas phase coupling of benzyl alcohol dehydrogenation with nitrobenzene hydrogenation for imine (N-benzylideneaniline) synthesis over mixtures of Cu/SiO2and (TiO2, MgO) supported Au catalysts has been established. The catalysts were characterised in terms of specific surface area, pore volume, TPR, H2chemisorption, STEM, XPS and TGA-DSC analysis. Au/TiO2prepared by deposition-precipitation exhibited a narrower particle size distribution (1–6 nm) and smaller mean (3.2 nm) than Au/MgO (1–15 nm, mean = 7.7 nm) prepared by impregnation. Dehydrogenation of benzyl alcohol (to benzaldehyde) over Cu/SiO2delivered a (ten-fold) higher rate than supported Au and Au/TiO2exhibited a higher H2chemisorption capacity and greater (by a factor of ten) nitrobenzene hydrogenation rate than Cu/SiO2and Au/MgO. Inefficient hydrogen utilisation is demonstrated for the cross-coupling reaction over Cu/SiO2alone and a temporal activity loss is linked to carbonaceous (benzoate) deposition (on the basis of XPS and TGA-DSC analysis). Incorporation of Au/TiO2(and Au/MgO) with Cu/SiO2increased the imine formation rate and H2utilisation efficiency. The combination of Au/TiO2with Cu/SiO2served to circumvent Cu/SiO2deactivation, resulting in enhanced stability with a four-fold increase in imine production and full H2utilisation at Cu/Au = 10.