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Cyclohexanone is widely used in coatings, pesticides, dyes, lubricants, and other industries due to its high solubility and low volatility, but designing highly active and stable heterogeneous cata...

The preparation of small molecule compounds with a high value from biomass has always been the focus of research, and catalysts with high activity and stability are an essential part of biomass con...

The new catalyst Pd@mSiO2 was synthesized by a simple and gentle one-step process, mesoporous silica as the shell and metal particles as the core. The characterization showed that the catalyst structure was regular, the core–shell structure was clear, and each microsphere guarantees the existence of a single nucleus. The pore size and the thickness of mesoporous silica layer can be effectively adjusted by adjusting the molecular weight of template and the amount of silicon source. The Pd@mSiO2 was applied in the hydrogenation of levulinic acid to prepare γ-valerolactone, the conversion of levulinic acid was 95%, and the selectivity of γ-valerolactone was close to 96%. In addition, the catalyst had a good reuse performance compared to commercial catalysts. After repeated use for ten times, the catalytic activity did not decrease, which was mainly attributed to the fact that the core–shell structure can better protect the active metal particles and prevent the particles from agglomeration and loss at high temperature.

The use of cellulose instead of oil to produce 1,2-propylene glycol (1,2-PG) is of great significance for building a sustainable world. Herein, we synthesize Fe3O4@SiO2/Ru-WOx core–shell magnetical...

The facile synthesis of yolk-shell-structured nanoparticles (YSNPs) with mobile active metal cores and mesoporous inorganic-organic hybrid silica shells (mHSiO2) is important for their applications. In this work, Pd@mHSiO2 YSNPs have been synthesized in aqueous solution at 95 °C by a one-pot method without the need for extensive purification and separation steps. The method is simple and facile, and ingeniously combines the controlled synthesis of Pd nanocubes, coating of mesoporous silica, and transition from core-shell-structured nanoparticles (CSNPs) to YSNPs. 29Si NMR spectroscopy, FTIR spectroscopy, and detailed control experiments have demonstrated that the incorporation of 1,2-bis(trimethoxysilyl)ethane (BTME) modifies the degree of condensation between the outer hybrid silica layer and the inner pure silica section, and that high temperature water is really responsible for dissolving the inner pure silica layer leading to a transition from the CSNPs to the YSNPs. The obtained Pd@mHSiO2 YSNPs have a controllable diameter, tunable shell thickness, a high specific surface area, and uniform mesoporosity. Thermal stability tests have indicated that the Pd@mHSiO2 YSNPs are remarkably stable at high temperatures up to 650 °C. Importantly, the Pd@mHSiO2 YSNPs exhibit a much higher catalytic activity and hydrothermal stability than Pd@mSiO2 CSNPs or Pd/mHSiO2 NSs in the conversion of levulinic acid (LA) into γ-valerolactone (GVL), because the hollow voids provide low mass-transfer resistance and improve the accessibility of the catalytic sites, and the incorporation of organic groups enhances the hydrothermal stability of the outer shell.

In this work, a series of Pd@Al-MSiO2 yolk–shell-structured nanospheres (YSNSs) with different Al contents were synthesized by a facile one-pot method. The EDX elemental analysis and high-magnification TEM image of Pd@Al-MSiO2 YSNSs confirmed that its well-defined yolk-shell structure with a moving Pd core and mesoporous silica shell rich in Al species. Furthermore, Solid state NMR and Py-FTIR results confirmed that Al species grafting mainly formed 4-coordinated Al (AlO4) in the mesoporous silica framework which led to generating abundant Lewis acid sites. The influence of Al species on the physicochemical properties of Pd@Al-MSiO2 YSNSs, as well as their catalytic performance for the hydrogenolysis of glucose to 1,2-propylene glycol (1,2-PG), was investigated. The mesoporous silica shell with abundant Lewis acid sites is a significant contributor to the isomerization of glucose into fructose, while the Pd core plays a role in promoting the hydrogenation of intermediates. The unique hollow space inside the Pd@Al-MSiO2 YSNSs provides a location for the retro-aldol condensation of fructose and consequently avoids direct hydrogenation of fructose. The as-synthesized Pd@Al3-MSiO2 YSNSs shows superior catalytic activity (1,2-PG selectivity of 47.4%, glucose conversion of 95.4%) in the hydrogenolysis of glucose, and far outperforms the Pd/Al3-MSiO2 catalysts. In addition, owing to the influence of the 4-coordinated Al species on the geometry and chemical properties of the mesoporous silica shell, the nanospheres show good stability and reusability over multiple catalytic cycles without significant loss of activity.

A supported ruthenium (Ru) nanoparticle on amino-functionalized Fe3O4 (Fe3O4/NH2/Ru) was successfully prepared by a novel and simple one-pot template-free method combined with a metal adsorption-reduction procedure. The characterization results show that the introduced amino group (1,6-hexanediamine) can effectively stabilize the Ru nanoparticles and allow the particles to maintain a narrow size distribution, monodispersity and a regular morphology. Fe3O4/NH2/Ru exhibits excellent catalytic activity for the transfer hydrogenation of nitro compounds by the use of NaBH4 as the hydrogen donor. The higher activity of this catalyst was attributed to the higher dispersion and smaller particle size of Ru nanoparticles, as observed from the characterization results. Moreover, the catalyst can be easily recovered by an external magnetic field, recycled five times and reused without any loss of activity.