Pd Nanoparticles Loaded on Ceramic Membranes by Atomic Layer Deposition with Enhanced Catalytic Properties

In-situ constructed tactic of palladium nanoparticles supported on hierarchical porous wood-derived cellulose framework towards efficient catalytic reduction on 4-nitrophenol

With the advancement of technology, the production of domestic sewage and industrial wastewater containing dyes are increasing steadily. In the evolutionary process of catalytic reduction wastewater, recyclability and homogenization are still puzzles. Herein, a wood-derived cellulose catalytic system with hierarchical pore structure was proposed based on chlorite-alkali method for efficient catalytic reduction on 4-nitrophenol (4-NP). The chlorite-alkali hydrolysis process played a significant role in enhancing channel connectivity and hydrophilicity of balsa (BS, O. pyramidale) when removing lignin and hemicellulose. The results of cumulative complete intrusion and extrusion showed that the porosity of BS increased from 76.07 % to 92.58 % after removing components. A universal in-situ constructed tactic of PdNPs supported on a dehemicellulose BS (DHBS) without external reducing agent. Additionally, the superhydrophilic hierarchical porous wood-derived cellulose structure had a synergistic effect with plasmonic enhancement of PdNPs on the catalytic reduction of 4-NP, resulting in reducing 4-NP rapidly, which achieving a reduction efficiency of 90 % in the 90 s with the rate constant of 1.51 min-1. The approach addressed the issue of low catalytic metal particle load and hider catalytic activity resulting from the limited thickness and porosity, and has a good application prospect in wastewater treatment.

Carbonized cellulose microspheres loaded with Pd NPs as catalyst in p-nitrophenol reduction and Suzuki-Miyaura coupling reaction

Catalytic reduction of p-nitrophenol is usually carried out using transition metal nanoparticles such as gold, palladium, silver, and copper, especially palladium nanoparticles (Pd NPs), which are characterized by fast reaction rate, high turnover frequency, good selectivity, and high yield. However, the aggregation and precipitation of the metals lead to the decomposition of the catalyst, which results in a significant reduction of the catalytic activity. Therefore, the preparation of homogeneous stabilized palladium nanoparticles catalysts has been widely studied. Stabilized palladium nanoparticles mainly use synthetic polymers. Cellulose microspheres, as a natural polymer material with low-cost and porous fiber network structure, are excellent carriers for stabilizing metal nanoparticles. Cellulose microspheres impregnated with palladium metal nanoparticles were carbonized to have a larger specific surface area and highly dispersed palladium nanoparticles, which exhibited excellent catalytic activity in the catalytic reduction of p-nitrophenol. In this work, the cellulose carbon-based microspheres palladium (Pd@CCM) catalysts were designed and characterized by SEM, TEM, EDS, XRD, FTIR, XPS, TGA, BET, and so on. Furthermore, the catalytic performance of Pd@CCM catalysts was investigated via p-nitrophenol reduction, which showed high catalytic activity. This catalyst also exhibited excellent catalytic performance in the Suzuki-Miyaura coupling reaction. Linking aromatic monomer and benzene through Suzuki-Miyaura coupling was presented as an effective route to obtaining biaryls, and the synthesis method is low-cost and simple. In addition, Pd@CCM showed desirable recyclability while maintaining its catalytic activity even after five recycles. This work is highly suggestive of the design and application of the heterogeneous catalyst.

Keys Unlocking Redispersion of Reactive PdOx Nanoclusters on Ce-Functionalized Perovskite Oxides for Methane Activation

Nowadays, trace CH₄ emitted from vehicle exhausts severely threaten the balance of the ecology system of our earth. Thereby, the development of active and stable catalysts capable of methane conversion under mild conditions is critical. Here, we present a convenient method to redisperse catalytically inert PdO nanoparticles (NPs) (>10 nm) into reactive PdO_x nanoclusters (∼2 nm) anchored on a Ce-doped LaFeO₃ parent. Isothermally activated in an N₂ flow, the redispersed catalyst achieved a CH₄ conversion of 90% at 400 °C, which is significantly higher than the fresh and H₂- and O₂-treated counterparts (625, 616, and 641 °C, respectively), indicating the importance of the gas atmosphere in the redispersion of PdO NPs. In addition, the comprehensive catalyst characterizations demonstrated that the isolated Ce ions in the perovskite lattice play an irreplaceable role in the redispersion of reactive sites and the reduction of the energy barrier for C-H scission. More importantly, the Ce additive helps to stabilize the PdO_x species by reducing overoxidation, resulting in significant lifetime extension. Through a thorough understanding of structural manipulation, this study sheds light on the design of highly performing supported catalysts for methane oxidation.

Highly effective catalytic reduction of nitrobenzene compounds with gold nanoparticle-immobilized hydroxyapatite nanowire-sintered porous ceramic beads

A catalytic ceramic bead with micron-sized and interconnected porous channels, adjustable porosity, high catalytic activity, and long-term stability is prepared.