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TiO2 Modification with Transition Metallic Species (Cr, Co, Ni, and Cu) for Photocatalytic Abatement of Acetic Acid in Liquid Phase and Propene in Gas Phase
摘要： The commercial P25 titania has been modi?ed with transition metallic species (Cr, Co, Ni, and Cu), added by impregnation with aqueous solutions of the corresponding nitrates. The preparation procedure also includes a heat treatment (500 ?C) in argon to decompose the nitrates, remove impurities and to strengthen the metal–TiO2 interaction. The catalysts have been thoroughly characterized using N2 adsorption, scanning electron microscopy (SEM), X-ray diffraction (XRD), UV-visible diffuse-re?ectance spectroscopy (UV-vis DRS) and X-ray photoelectron spectroscopy (XPS), and have been tested in the aqueous phase decomposition of acetic acid and in the gas phase oxidation of propene, using an irradiation source of 365 nm in both cases. The photocatalytic activity of the four metal-containing catalysts varies with the nature of the metallic species and follows a similar trend in the two tested reactions. The effect of the nature of the added metallic species is mainly based on the electrochemical properties of the supported species, being Cu/P25 (the sample that contains copper) the best performing catalyst. In the photodecomposition of acetic acid, all the metal-containing samples are more active than bare P25, while in the gas phase oxidation of propene, bare P25 is more active. This has been explained considering that the rate-determining steps are different in gas and liquid media.
关键词： TiO2,P25,propene,photocatalysis,acetic acid,transition metals
更新于2025-09-23 15:22:29
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Wideband Sidelobe-Level Reduced Ka-Band Metasurface Antenna Array Fed by Substrate Integrated Gap Waveguide Using Characteristic Mode Analysis
摘要： The control of the shape and dispersibility of Pt nanoparticles (NPs) supported on Al2O3 is challenging. To address this issue, the use of metal-organic frameworks as a template for the preparation of heterogeneous catalysts is a promising methodology. Herein, we used an Al-based metal-organic framework as a medium to synthesize uniform Pt NPs supported on γ-Al2O3 (Pt@γ-Al2O3) in the absence of protective and capping agents and subjected these nanoparticles to instrumental analyses. Microscopic imaging indicated that nanoparticles had diameters of 2–5 nm (mean ? 3.4 nm) and revealed the formation of Pt nanocubes on the alumina surface. Pt@γ-Al2O3 exhibited excellent catalytic activity for propene oxidation and displayed long-term stability, with the corresponding activation energy determined as 63.9 kJ mol?1. Moreover, Pt@γ-Al2O3 also effectively catalyzed the gas-phase hydrogenation of nitrobenzene to aniline at 100 °C, achieving a turnover frequency of 565 h?1 and a selectivity of >90%. Thus, the obtained results contribute to the further development of supported heterogeneous catalysts from metal-organic frameworks as precursors and media.
关键词： Nitrobenzene hydrogenation,MIL-53(Al),Pt@γ-Al2O3,Total propene oxidation
更新于2025-09-11 14:15:04