咪唑基双功能PMO纳米空间中支持的钯纳米颗粒：塞子在酒精好氧氧化中选择性转化中的作用,ACS Catalysis

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咪唑基双功能PMO纳米空间中支持的钯纳米颗粒：塞子在酒精好氧氧化中选择性转化中的作用
ACS Catalysis ( IF 11.3 ) Pub Date : 2015-06-12 00:00:00 , DOI: 10.1021/acscatal.5b00237
Babak Karimi ₁ , Mojtaba Khorasani ₁ , Hojatollah Vali ₂ , Carolina Vargas ₃ , Rafael Luque ₄

Affiliation

已经描述了由钯纳米颗粒组成的新型非均相催化剂体系，该钯纳米颗粒固定在咪唑基双功能插入和未插入的周期性介孔有机二氧化硅（BFPMO）的纳米空间中，用于选择性好氧氧化水中的醇。BFPMO的特征在于N ₂吸附-解吸分析，透射电子显微镜（TEM），粉末X射线衍射（PXRD），热重分析（TGA），²⁹ Si和¹³C交叉极化魔角旋转（CP MAS）NMR光谱，漫反射红外傅里叶变换光谱（DRIFT），元素分析，扫描电子显微镜（SEM）和X射线光电子能谱（XPS）。通过强调不同的理化性质以及塞子对反应选择性的影响，研究了在苯甲醇的好氧氧化过程中所有堵塞和未堵塞催化剂的催化活性。尽管未封端的催化剂表现出更好的苄醇选择性氧化为苯甲醛的活性，但在完全相同的反应条件下，在存在封端催化剂的情况下，选择性模式以高收率和选择性转移至苯甲酸。研究首次表明，改变疏水-亲水平衡，并伴随控制所述催化剂的介孔内部的塞子，可以通过协同机制调节催化剂性能和反应选择性。已经提出了可能的模型来解释这种空前的观察。

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Palladium Nanoparticles Supported in the Nanospaces of Imidazolium-Based Bifunctional PMOs: The Role of Plugs in Selectivity Changeover in Aerobic Oxidation of Alcohols

Novel heterogeneous catalyst systems comprised of palladium nanoparticles immobilized into the nanospaces of imidazolium-based bifunctional plugged and unplugged periodic mesoporous organosilicas (BFPMO) have been described for the selective aerobic oxidation of alcohols in water. BFPMOs were characterized by N₂ adsorption–desorption analysis, transmission electron microscopy (TEM), powder X-ray diffraction (PXRD), thermal gravimetric analysis (TGA), ²⁹Si and ¹³C cross-polarization magic angle spinning (CP MAS) NMR spectroscopy, diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), elemental analysis, scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The catalytic activity of all plugged and unplugged catalysts was investigated in the aerobic oxidation of benzylic alcohols by emphasizing the effect of different physiochemical properties as well as the plugs on the reaction selectivity. While unplugged catalysts exhibited much better activity for the selective oxidation of benzyl alcohol to benzaldehyde, the selectivity pattern shifts to the benzoic acid in high yield and selectivity in the presence of plugged catalyst under the exact same reaction conditions. The studies showed for the first time that varying the hydrophobic–hydrophilic balance with concomitant control of plugs in the interior of the mesochannels of the described catalyst enabled tuning of both the catalyst performance and the reaction selectivity, possibly through a cooperative mechanism. A possible model has been proposed to explain this unprecedented observation.

更新日期：2015-06-12

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