从生物质衍生的活性炭开发多相催化剂是一项具有挑战性的任务。生物质活性炭具有较大的比表面积、高度多孔的结构和良好的热/化学稳定性。基于生物质活性炭的磁性铜催化剂在无碱 Chan-Lam 偶联和氧化反应中表现出良好的催化活性。在此,通过将印楝枯叶(大量废生物质)碳化,然后用 KOH 进行化学活化来制备生物质衍生的活性炭。这种多孔碳材料被用作低成本、高效的载体材料,用于制备廉价且环境友好的磁性催化剂[Cu@KF-C/MFe 2 O 4 ,M = Co、Cu、Ni和Zn]。此外,还进行了 KF 改性,赋予催化剂碱性特征,使其能够在无碱条件下进行 C-N 偶联。最初,对合成的催化剂进行了Brunauer-Emmett-Teller (BET)分析,结果表明Cu@KF-C/CoFe 2 O 4具有更大的表面积和孔体积,因此在其中具有最高的活性。其他合成催化剂。此外,进行了X射线光电子能谱(XPS)分析,推断Cu@KF-C/CoFe 2 O 4含有大部分还原形式的铜,即Cu(0),它是负责对 Chan-Lam 偶联反应以及醇和碳氢化合物的氧化具有更好的催化活性。 通过BET、XPS、傅里叶变换红外光谱(FTIR)、热重分析(TGA)、场发射枪扫描电子显微镜(FEG- SEM)、高分辨率透射电子显微镜 (HR-TEM)、能量色散 X 射线 (EDX) 测绘、能量色散 X 射线 (EDX)、电感耦合等离子体原子发射光谱 (ICP-AES)、粉末 X 射线衍射 (XRD) 和振动样品磁力测定 (VSM)。此外,Cu@KF-C/CoFe 2 O 4表现出优异的稳定性和可重复使用性,并且可以借助外部磁铁轻松分离。
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Biomass-Derived Activated Carbon-Supported Copper Catalyst: An Efficient Heterogeneous Magnetic Catalyst for Base-Free Chan–Lam Coupling and Oxidations
Development of heterogeneous catalysts from biomass-derived activated carbon is a challenging task. Biomass-derived activated carbon possesses a large specific surface area, highly porous structure, and good thermal/chemical stability. Magnetic copper catalysts based on biomass-derived activated carbon exhibited good catalytic activity in base-free Chan–Lam coupling and oxidations. Herein, biomass-derived activated carbon was prepared by the carbonization of neem dead leaves (abundant waste biomass) followed by chemical activation with KOH. Such a porous carbon material was used as a low cost and highly efficient support material for the preparation of inexpensive and environmentally benign magnetic catalysts [Cu@KF-C/MFe2O4, M = Co, Cu, Ni, and Zn]. In addition, KF modification was done to impart basic character to the catalyst that can perform C–N coupling under base-free conditions. Initially, Brunauer–Emmett–Teller (BET) analysis of the synthesized catalysts was carried out, which indicated that Cu@KF-C/CoFe2O4 possess more surface area as well as pore volume, and so accounting for the highest activity among the other synthesized catalysts. Further, X-ray photoelectron spectroscopy (XPS) analysis was performed, which inferred that Cu@KF-C/CoFe2O4 contains most of the copper in reduced form, i.e., Cu(0), which is the active species responsible for better catalytic activity toward Chan–Lam coupling reactions as well as oxidation of alcohols and hydrocarbons. The physiochemical properties of the most active catalyst, Cu@KF-C/CoFe2O4, was examined by BET, XPS, Fourier transform infrared Spectroscopy (FTIR), thermogravimetric analysis (TGA), field emission gun scanning electron microscopy (FEG-SEM), high-resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray (EDX) mapping, energy dispersive X-ray (EDX), inductively coupled plasma atomic emission spectroscopy (ICP-AES), powder X-ray diffraction (XRD), and vibrating sample magnetometry (VSM). Moreover, Cu@KF-C/CoFe2O4 shows excellent stability as well as reusability and could be easily separated with the help of an external magnet.