Chemoselective hydrogenation of 3-nitrostyrene to 3-aminostyrene over Pt-Bi/TiO 2 catalysts

Single-ion chelation strategy for synthesis of monodisperse Pd nanoparticles anchored in MOF-808 for highly efficient hydrogenation and cascade reactions

Ultrafine Pd nanoparticles are prepared using a single-ion precursor on a MOF-808 carrier. The ligand 2,3-pyrazinedicarboxylic acid (Pza) is dispersed in porous MOF-808 via grafting on formic acid sites, and thus Pd²⁺ ions are chelated by Pza to form a new single-ion precursor Pd@MOF-808-Pza. Then a Pd-nano@MOF-808-Pza catalyst is prepared by direct reduction of this precursor using NaBH₄. Material characterization reveals the homogeneous dispersion of 3-6 nm Pd nanoparticles within the MOF-808 matrix. Pd-nano@MOF-808-Pza exhibits excellent catalytic activity in the hydrogenation of unsaturated nitrogen-containing compounds, and other typical reactions, such as the Knoevenagel condensation, Suzuki/Heck cross-coupling, and hydrogen tandem reactions. In addition, density functional theory (DFT) calculations are carried out to elucidate the chelation of Pd²⁺ ions by Pza on MOF-808 and propose mechanisms of hydrogenation reactions. This work provides an effective reduction catalyst, and more importantly, a single-ion chelation strategy for design and synthesis of metal supported catalysts.

Hybrid Nanostructure Catalyst with Low Loading of Pt for the High-Efficiency Catalytic Hydrogenation of Chloronitrobenzene

Fabrication of low-loading, noble-metal, stable, and high-performance metal catalysts remains a thorny issue. Herein, we demonstrate the successful formation of a hybrid nanostructure Pt/TiO₂/SBA-15 catalyst (denoted as HNSC-P/T/S; Pt, 0.09%; TiO₂, 10%) with satisfactory activity in the hydrogenation of para-chloronitrobenzene (p-CNB). The HNSC-P/T/S showed >99% conversion and a high selectivity of >98%, and the turnover frequency number (TOF) reached 66 766 h^-1, which was impossible to achieve with Pt/TiO₂ (denoted as P/T) or Pt/SBA-15 (denoted as P/S). The success of the catalytic activity of the HNSC-P/T/S mainly relies on its synergistic effect and special structure, which can fully develop the catalytic ability of Pt, thereby reducing the Pt loading in the noble-based catalyst. Furthermore, the HNSC-P/T/S could also achieve an excellent catalytic activity in the hydrogenation of other nitroarenes. Hence, this work proposes a direction to prepare a noble-based catalyst with a low loading of noble metals for diverse applications.

Unique structure of active platinum-bismuth site for oxidation of carbon monoxide

As the technology development, the future advanced combustion engines must be designed to perform at a low temperature. Thus, it is a great challenge to synthesize high active and stable catalysts to resolve exhaust below 100 °C. Here, we report that bismuth as a dopant is added to form platinum-bismuth cluster on silica for CO oxidation. The highly reducible oxygen species provided by surface metal-oxide (M-O) interface could be activated by CO at low temperature (~50 °C) with a high CO2 production rate of 487 μmolCO2·gPt-1·s-1 at 110 °C. Experiment data combined with density functional calculation (DFT) results demonstrate that Pt cluster with surface Pt-O-Bi structure is the active site for CO oxidation via providing moderate CO adsorption and activating CO molecules with electron transformation between platinum atom and carbon monoxide. These findings provide a unique and general approach towards design of potential excellent performance catalysts for redox reaction.

Colloidal Palladium Nanoparticles for Selective Hydrogenation of Styrene Derivatives with Reactive Functional Groups

This article presents the catalysis investigation of octanethiolate-capped palladium nanoparticles (C8 PdNP) and phenylethanethiolate-capped palladium nanoparticles (PhC2 PdNP) for chemoselective catalytic hydrogenation reactions of styrene derivatives in the presence of other reducible functionalities. The results show that the C8 PdNP is highly active under mild reaction conditions (room temperature and atmospheric pressure) and selective for hydrogenating monosubstituted alkene groups without reducing other reactive functional groups such as nitro, halo, carbonyls, and so forth. In comparison, the noncovalent interactions between surface phenyl ligands and aromatic substrates are found to hinder the hydrogenation activity of PhC2 PdNP.

New insight into the enhanced catalytic performance of ZnPt/HZSM-5 catalysts for direct dehydrogenation of propane to propylene

Framework Zn species and small-sized PtZn particles in ZnPt/HZSM-5 catalyst function cooperatively in PDH, showing excellent performance at 525 °C.

A new nano-photocatalyst based on Pt and Bi co-doped TiO2 for efficient visible-light photo degradation of amoxicillin

Herein, the photo degradation of amoxicillin (AMX) was thoroughly investigated using Pt and Bi co-doped TiO₂ photocatalysts under visible-light irradiation.