Tunning of catalytic performance in coupling, reduction and oxidation of hydrothermal assisted mixed metal oxides of Pd and Cu loaded over mesoporous nanostructure titania coated N-doped silica using rice husk

Silica-titania-based mesoporous nanomaterials due to their widespread availability and inexpensive cost have been employed in an extensive range of applications, including heterogeneous catalysis. This research article discusses the hydrothermal synthesis of highly efficient heterogeneous nanocatalyst, that is, mixed metal oxides of Pd and Cu immobilized over silica-titania mesoporous nanostructure and its application in coupling, reduction and oxidation reactions. It was characterized by Fourier transform infrared spectroscopy (FTIR), powder X-ray diffraction (P-XRD), field emission gun-scanning electron microscopy (FEG-SEM), energy-dispersive X-ray analysis (EDX), high-resolution transmission electron microscopy (HR-TEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), UV-visible spectroscopy (UV-VIS), Brunauer-Emmett-Teller (BET), X-ray resonance fluorescence (XRF), photoluminescence (PL) and inductively coupled plasma-atomic emission spectroscopy (ICP-AES) studies to assemble information regarding various structural features. XPS analysis successfully confirmed the presence of mixed oxidation state of Pd and Cu, that is, Pd(0), Pd(II), Cu(0), Cu(I) and Cu(II) over the nanocatalytic support. TEM images showed that the PdCu alloy had spherical shape with average size between 3 and 4 nm. BET analysis indicated that the catalyst has specific surface area of 57.296 m2 g-1 with average pore diameter of 1.84 nm. The results of TGA and DTA analysis demonstrated that the maximum temperature up to which PC-TNS can catalysed organic reactions was 170 degrees C. The average crystallite size of PC-TNS was came around 16.08 nm calculated using Scherrer's equation. Moreover, synthesized heterogeneous nanocatalyst was highly recyclable and FEG-SEM, P-XRD and XPS findings confirmed the structural disruption after sixth or seventh catalytic run resulted in decrease in yield of products. In general, nanocatalysts can be convincingly more superior to other heterogeneous nanocatalyst due to their unique features such as high specific surface area, high reusability, high reactivity, high product yield and environmentally friendly. In this article, PdCu@TiO2-NSiO2 (PC-TNS) was synthesized via hydrothermalroute taking rice husk as a precursor for nanosilica powder. Its applicationwas explored in Suzuki-Miyaura coupling, Chan-Lam coupling, reduction andoxidation. Several spectroscopic techniques were used to study PC-TNS to getstructural details. The catalyst showed excellent reusability, and recycledcatalyst was also characterized. In C-C coupling, C-N coupling and inreduction, nanocatalyst supported a broad variety of substrates with diverse functional group tolerance and produced good yield ofthe desired product. image