Propane dehydrogenation (PDH) offers a promising route for on-demand propylene production, yet developing cost-effective and durable non-noble metal catalysts remains challenging. Herein, we report a silanol (Si–OH) stabilized Zn catalyst supported on hierarchical self-pillared pentasil (SPP) zeolite, synthesized via the metal-ligand protection strategy under one-pot hydrothermal condition. The abundant isolated silanol groups on the SPP framework effectively anchor Zn2+ ions, forming highly dispersed subnanometric ZnO clusters confined within zeolite channels without forming bulk particles. Structural characterization (powder X-Ray diffraction (PXRD), Fourier transform infrared (FTIR), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), X-ray photoelectron spectroscopy (XPS)) confirms the atomic-level dispersion of Zn species and their strong interaction with silanol defects. At an optimal Zn loading of 2.65 wt.%, the catalyst achieves 33.7% propane conversion with 92.7% propylene selectivity and a space-time yield of 179.9 mg·g−1·h−1 at 550 °C under a weight hourly space velocity (WHSV) of 0.6 h−1. Remarkably, the catalyst retains > 90% selectivity and recovers 80% initial activity after two regeneration cycles, attributed to minimized coke deposition (< 0.3 wt.%) and suppressed Zn loss. Mechanistic studies reveal that silanol-mediated Zn stabilization optimizes propane C–H activation, while the hierarchical porosity of SPP enhances mass transport and coke resistance. This work underscores the critical role of support surface chemistry and architecture in designing robust propane dehydrogenation (PDH) catalysts, offering a viable pathway to replace conventional noble or toxic metal-based systems.
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Oxide-supported metal single-atom catalysts (SACs) have exhibited excellent catalytic performance for water–gas shift (WGS) reaction. Here, we report the single-atom catalyst Pt1/FeOx exhibits excellent medium temperature catalytic performance for WGS reactions by the density functional theory (DFT) calculations and experimental results. The calculations indicate that H2O molecules are easily dissociated at oxygen vacancies, and the formed *OH and *O are adsorbed on Pt1 single atoms and the adjacent O atoms, respectively. After studying four possible reaction mechanisms, it is found that the optimal WGS reaction pathway is proceeded along the carboxyl mechanism (pathway III), in which the formation of *COOH intermediates can promote the stability of Pt1/FeOx SAC and the easier occurrence of WGS reaction. The energy barrier of the rate-determining step during the entire reaction cycle is only 1.16 eV, showing the high activity for the medium temperature WGS reaction on Pt1/FeOx SAC, which was verified by experimental results. Moreover, the calculated turnover frequencies (TOFs) of CO2 and H2 formation on Pt1/FeOx at 610 K (337 °C) can reach up to 1.14 × 10−3 s−1·site−1 through carboxyl mechanism. In this work, we further expand the application potential of Pt1/FeOx SAC in WGS reaction.
Alcohol-based disinfectants have protected people in the coronavirus disease 2019 (COVID-19) pandemic, but olfactory stimuli of ethanol may evoke unpleasant memories associated with stressful situations in the devastating infectious disease. The smell of ethanol in household cleaning and disinfectant products can be covered up by the fragrance additives, and 3-hexenol is especially appreciated for the characteristic, strong odor of green plants. Industrial production of 3-hexenol relies on the selective hydrogenation of 3-hexyn-1-ol, where Lindlar catalyst is normally used for the superior selectivity. Although achieving such catalytic transformation in ethanol solution seems as a direct way to produce a disinfectant with green aroma, a popular consumer product in the post-COVID era, severe leaching of toxic Pb hinders Lindlar catalyst as a promising candidate. We find that the Fe2O3 supported Pd single-atom catalyst is highly selective to fulfill semi-hydrogenation of 3-hexyn-1-ol in 75% ethanol, and the aforementioned household product is readily generated after filtrating the stable, solid catalyst out of reaction solution. Single-atom catalysts have been frequently utilized for fine-chemical synthesis, while in this work they make stunning debut in practical manufacture of daily used products.
Gold-based catalysts are promising in CO preferential oxidation (CO-PROX) reaction in H2-rich stream on account of their high intrinsic activity for CO elimination even at ambient temperature. However, the decrease of CO conversion at elevated temperature due to the competition of H2 oxidation, together with the low stability of gold nanoparticles, has posed a dear challenge. Herein, we report that Au-Cu bimetallic catalyst prepared by galvanic replacement method shows a wide temperature window for CO total conversion (30–100 °C) and very good catalyst stability without deactivation in a 200-h test. Detailed characterizations combined with density functional theory (DFT) calculation reveal that the synergistic effect of Au-Cu, the electron transfer from Au to Cu, leads to not only strengthened chemisorption of CO but also weakened dissociation of H2, both of which are helpful in inhibiting the competition of H2 oxidation thus widening the temperature window for CO total conversion.
Selective hydrogenation of acetylene in excess ethylene is an important reaction in both fundamental study and practical application. Pd-based catalysts with high intrinsic activity are commonly employed, but usually suffer from low selectivity. Pd single-atom catalysts (SACs) usually exhibit outstanding ethylene selectivity due to the weak π-bonding ethylene adsorption. However, the preparation of high-loading and stable Pd SACs is still confronted with a great challenge. In this work, we report a simple strategy to fabricate Pd SACs by means of reducing conventional supported Pd catalysts at suitable temperatures to selectively encapsulate the co-existed Pd nanoparticles (NPs)/clusters. This is based on our new finding that single atoms only manifest strong metal–support interaction (SMSI) at higher reduction temperature than that of NPs/clusters. The derived Pd SACs (Pd1/CeO2 and Pd1/α-Fe2O3) were applied to acetylene selective hydrogenation, exhibiting much improved ethylene selectivity and high stability. This work offers a promising way to develop stable Pd SACs easily.
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