Polyacrylamide-g-Reduced Graphene Oxide Supported Pd Nanoparticles as a Highly Efficient Catalyst for Suzuki–Miyaura Reactions in Water

Catalysis Letters - To improve the dispersibility of graphene oxide (GO) in solvents, the grafting of polyacrylamide (PAM) from the GO surface was performed by redox polymerization system. The...     

Palladium Nanoparticles Supported on Poly(2-hydroxyethyl methacrylate)/KIT-6 Composite as an Efficient and Reusable Catalyst for Suzuki–Miyaura Reaction in Water

Pd nanoparticle-poly(2-hydroxyethyl methacrylate)/KIT-6 (Pd-PHEMA/KIT-6) composite was fabricated through in situ polymerization method and was evaluated as a novel heterogeneous catalyst in Suzuki–Miyaura cross coupling reactions of aryl halides and phenylboronic acid in an aqueous medium. The catalyst was characterized by XRD, FT-IR, UV–Vis, TG, BET, and TEM techniques. The results revealed that the supported catalyst Pd-PHEMA/KIT-6 exhibited excellent catalytic activity for the coupling of aryl iodides, aryl bromides, and aryl chlorides. This heterogeneous catalyst could be reused at least nine times without any decrease in activity.     

Bimetallic Pd–Cu/ZnO–Al<Subscript>2</Subscript>O<Subscript>3</Subscript> and Pd–Cu/ZrO<Subscript>2</Subscript>–Al<Subscript>2</Subscript>O<Subscript>3</Subscript> catalysts for methanol synthesis

Monometallic copper and bimetallic palladium-copper catalysts supported on ZnO–Al₂O₃ and ZrO₂–Al₂O₃ were prepared by conventional impregnation method and tested in methanol synthesis reaction under elevated pressure (3.5 MPa) in gradientless reactor at 220°C. The physicochemical properties of prepared catalytic systems were studied using BET, X-ray, TPR-H₂, TPD-NH₃ techniques. The promotion effect of palladium on catalytic activity and selectivity of copper supported catalyst in methanol synthesis reaction was proven. The highest activity of this system is explained by the Pd–Cu alloy formation.     

An Efficient and Eco-friendly MoO<Subscript>3</Subscript>–SiO<Subscript>2</Subscript> Solid Acid Catalyst for Electrophilic Aromatic Nitration with N<Subscript>2</Subscript>O<Subscript>5</Subscript>

Abstract  

Electrophilic aromatic nitration using N₂O₅ as a green nitrating agent catalyzed by MoO₃–SiO₂ under mild conditions has been described. A series of MoO₃–SiO₂ catalysts with varying MoO₃ loadings (5–20 mol%) were prepared by sol–gel technique and characterized using FTIR, XRD, SEM, BET and NH₃–TPD to study its surface properties. MoO₃–SiO₂ shows good catalytic activity and reusability for the nitration of alkyl and halogen aromatics giving high conversions, but less efficiency for the deactivated aromatics. Reactions conducted under non-acidic conditions using N₂O₅ makes the process safe and environmentally friendly.     

Synthesis of the study of solid solutions based on the ZrO<Subscript>2</Subscript>–HfO<Subscript>2</Subscript>–Y<Subscript>2</Subscript>O<Subscript>3</Subscript>(CeO<Subscript>2</Subscript>) system

The results of the studies of the conditions of the liquid-phase synthesis of highly dispersed xerogels with a low degree of agglomeration and precursor nanopowders (~10–12 nm) based on zirconium dioxide in the ZrO₂–HfO₂–Y₂O₃(CeO₂) system are presented. The thermal decomposition of xerogels and formation of crystalline solid solutions with the structure of fluorite are investigated. The optimal conditions for the solidification of nanodispersed powders for fabricating compact ceramics based on solid solutions of ZrO₂ and the physical–chemical properties of these ceramics are studied.     

Pd(II)/Pd(0) Anchored on Magnetic Organic–Inorganic Hybrid Mesoporous Silica Nanoparticles: A Nanocatalyst for Suzuki–Miyaura and Heck–Mizoroki Coupling Reactions

Journal of Inorganic and Organometallic Polymers and Materials - 3-Chloropropyltrimethoxysilane (CPTMS) was grafted on the surface of silica coated Fe3O4 core (Fe3O4@MCM-41) and then condensed with...     

Synthesis and physicochemical properties of a solid oxide nanocomposite based on a ZrO<Subscript>2</Subscript>–Y<Subscript>2</Subscript>O<Subscript>3</Subscript>–Gd<Subscript>2</Subscript>O<Subscript>3</Subscript>–MgO system

A highly dispersive powder with a (ZrO₂)_0.92(Y₂O₃)_0.03(Gd₂O₃)_0.03(MgO)_0.02 composition and specific surface area of 150 m²/g has been synthesized via a method of coprecipitation of hydroxides with the subsequent cryochemical treatment of the gel. Nanoceramics based on the cubic modification of zirconium dioxide with the grain size of ~40–45 nm have been obtained. The temperature dependence of the specific electrical conductance of the nanoceramics within a temperature range of 350–870°C in air has been studied, and the ratio of the ionic and electronic parts of the conductance has been determined. Recommendations for the use of the obtained oxide nanocomposite as an electrolyte for a high-temperature fuel cell have been given.     

Porous ceramics based on the ZrO<Subscript>2</Subscript>(Y<Subscript>2</Subscript>O<Subscript>3</Subscript>)–Al<Subscript>2</Subscript>O<Subscript>3</Subscript> system for filtration membranes

The results of the studies of the process of fabricating ceramic filtration membranes in the system ZrO₂(Y₂O₃)–Al₂O₃ are presented. The phase compositions of the precursor powders and sintered ceramics have been investigated and their porous structures have been determined. Two stages of the implementation of the technology were demonstrated: fabrication of substrates with an open porosity ranging from 20 to 47% and pore sizes in the 100–300 nm range, as well as the deposition of nanocrystalline aluminum oxide layers on them. It has been established that the pore size distribution in the membrane layer of α-Al₂O₃ is unimodal (from 30 to 100 nm).