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In this work, for the first time, naphthalene (NA)-based polymers were synthesized by one-stage Friedel–Crafts crosslinking. The influence of NA functionalization by -OH, -SO3H, and -NO2 groups on the polymers' porosity and distribution of the catalytically active phase (Pd) was studied. Synthesized catalytic systems containing 1 wt.% of Pd either in the form of Pd(II) species or Pd(0) nanoparticles supported on NA-based polymers were tested in a model reaction of Suzuki cross-coupling between 4-bromoanisole and phenylboronic acid under mild reaction conditions (60 °C, ethanol-water mixture as a solvent). These novel catalysts demonstrated high efficiency with more than 95% of 4-bromoanisole conversion and high selectivity (>97%) for the target 4-methoxybiphenyl. [ABSTRACT FROM AUTHOR]

Lignin obtained by hydrogenolysis of lignocellulose biomass is a prospective source of valuable green fuels and chemicals such as monophenols. One of the key factors in the chemical decomposition of lignin to monophenols is an efficient catalyst. Inert porous materials such as hypercrosslinked polymers are suitable catalytic supports for the immobilization of noble and transition metal nanoparticles. However, such polymers do not have acidic properties, which are crucial for catalyzing hydrolysis. In this work, we report novel, efficient catalysts for lignin hydrogenolysis to produce valuable monophenolic compounds. The synthesized catalysts contained Ni, Ru, and Ni–Ru nanoparticles supported on SiO2-coated hypercrosslinked polystyrene (SiO2@HPS). Ni-Ru/SiO2@HPS demonstrated remarkable stability without any loss of the metallic phase and a high yield of monophenols (>42 wt.%) at close to full lignin conversion (>95 wt.%). This result was attributed to the synergy between the two metals and the support's surface acidity. All catalysts were fully characterized by a series of physico-chemical methods. [ABSTRACT FROM AUTHOR]

Carbon materials are widely used in catalysis as effective catalyst supports. Carbon supports can be produced from coal, organic precursors, biomass, and polymer wastes. Biomass is one of the promising sources used to produce carbon-based materials with a high surface area and a hierarchical structure. In this review, we briefly discuss the methods of biomass-derived carbon supported catalyst preparation and their application in biodiesel production, organic synthesis reactions, and electrocatalysis. [ABSTRACT FROM AUTHOR]

The modification of fatty substrates using heterogeneous catalysts have extensive industrial application and has an emphatic position in a sustainable context. Herein ruthenium, nickel, cobalt and copper-doped ruthenium, supported on hypercrosslinked polystyrene (HPS) catalysts were prepared by wet impregnation, characterized and applied on the modification of canola fatty acid methyl esters (FAME). The characterization showed a dispersive effect of doping metals over the ruthenium particles, the presence of acid sites and overall surface morphology, which allows targeting potential applications. The chosen modifications consisted of hydrogenation, hydroformylation, oxidative cleavage and deoxygenation, resulting in superb catalytic activities of over 99% conversions for hydrogenation and deoxygenation. The simplicity of the canola FAME composition allows the understanding of the catalytic processes and allows the upscale of more complex FAME matrixes. Finally, the obtained data stimulates further optimization studies for each application with a variation on the catalysts and the usage of residual fatty substrates, greatly enhancing the sustainability profile of the systems. [ABSTRACT FROM AUTHOR]

In recent years, composite materials including organic–inorganic systems have drawn special attention due to their enhanced properties such as adsorbents and heterogeneous catalysts. At the same time, large-scale production of environmentally benign functionalized biopolymers, such as chitosan (CS), allows for constantly developing new materials, since CS reveals remarkable properties as a stabilizing agent for metal-containing compounds and enzymes and as an adsorbent of organic molecules. This review is focused on CS-based materials and on the composite systems including CS-oxide and CS-metal composites in particular for application as adsorbents and supports for catalytically active metal nanoparticles and enzymes. [ABSTRACT FROM AUTHOR]

ZnO supported on hypercrosslinked polystyrene was developed for liquid-phase methanol synthesis. The synthesized catalyst was characterized using the low-temperature nitrogen physisorption, TEM, XPS, XAS, and CO DRIFT methods. The analysis showed that the catalyst has a high specific surface area (720 m2/g) and is characterized by the micro-mesoporous structure typical of the polymer used. The active phase is represented by ZnO species with a hexagonal wurtzite structure. ZnO-HPS showed high activity, selectivity, and stability in liquid-phase methanol synthesis in comparison with the industrial catalyst. The activity of the proposed catalyst was found to be 1.64 times higher than that of the conventional Cu/ZnO/Al2O3. [ABSTRACT FROM AUTHOR]

CO2 hydrogenation to methanol is an important process that could solve the problem of emitted CO2 that contributes to environmental concern. Here we developed Cr-, Cr-Zn-, and Cr-Ni-containing nanocomposites based on a solid support (SiO2 or Al2O3) with embedded magnetic nanoparticles (NPs) and covered by a cross-linked pyridylphenylene polymer layer. The decomposition of Cr, Zn, and Ni precursors in the presence of supports containing magnetic oxide led to formation of amorphous metal oxides evenly distributed over the support-polymer space, together with the partial diffusion of metal species into magnetic NPs. We demonstrated the catalytic activity of Cr2O3 in the hydrogenation reaction of CO2 to methanol, which was further increased by 50% and 204% by incorporation of Ni and Zn species, respectively. The fine intermixing of metal species ensures an enhanced methanol productivity. Careful adjustment of constituent elements, e.g., catalytic metal, type of support, presence of magnetic NPs, and deposition of hydrophobic polymer layer contributes to the synergetic promotional effect required for activation of CO2 molecules as well. The results of catalytic recycle experiments revealed excellent stability of the catalysts due to protective role of hydrophobic polymer. [ABSTRACT FROM AUTHOR]

Influence of heterogenization on catalytic properties of block copolymer micellar catalysts derived from polystyrene-block-poly-4-vinylpyridine and containing Pd monometallic and bimetallic PdAu, PdPt, and PdZn nanoparticles has been studied in selective hydrogenation of the triple bond of 3,7-dimethyloctaen-6-yne-1-ol-3 (dehydrolinalool). We demonstrate that the heterogenization can both increase and decrease catalytic activity depending on the type of NPs. In the absence of a modifying metal (Pd monometallic nanoparticles) or for PdZn nanoparticles where Zn is the electron donor, the activity of heterogenized catalysts increases, while for PdAu and PdPt based catalysts, where the modifying metal is the electron acceptor, the activity decreases. These changes are explained by the increased polarity of the catalyst after deposition on alumina (addition of a component with a higher dielectric constant) offset by poor accessibility of some catalytic sites of nanoparticles containing electron deficient Pd atoms. [Copyright &y& Elsevier]

Alkane production from fatty acids and their derivatives can be considered one of the most‐studied processes. Such reactions as hydrogenation, hydrodeoxygenation, decarboxylation, and decarbonylation are the main routes for this process. The reaction pathway depends on the nature of the catalyst, the presence of hydrogen, and the hydrogen source. In this work, a mixture of unsaturated fatty acids (oleic and linoleic acids) was converted to alkanes (mainly heptadecane) in a hydrogen‐free atmosphere by using 2‐propanol as hydrogen donor. Transition metal doped Pd catalysts embedded on a porous organic support (hypercrosslinked polystyrene) were used as catalysts. A Pd‐Cu catalyst showed the highest effectiveness, allowing up to 99.9 mol % selectivity to heptadecane to be obtained. The process proceeds through fatty acid esterification, further hydrogenation of double bonds, and decarboxylation to form n‐heptadecane as main product. [ABSTRACT FROM AUTHOR]

Hydrogenation of aromatic compounds is a widely used catalytic process in modern industry. Selective hydrogenation of benzene (BZ)‐toluene (TL) mixtures is an important industrial process as it allows the purification of BZ for further synthetic purposes. In this work, the hydrogenation of a BZ‐TL mixture (at a molar ratio close to 1) was studied for varying reaction parameters (temperature in the range of 100–180 °C and pressure in the range of 1–7 MPa) using Pt‐, Pd‐, and Ru‐containing nanoparticles stabilized by an amino‐functionalized hyper‐crosslinked aromatic polymer (HAP). Among the synthesized catalytic systems, Ru/HAP containing ruthenium(IV) oxide was shown to be the most active and selective one, allowing 44 % selectivity with respect to cyclohexane at nearly 100 % of BZ conversion. [ABSTRACT FROM AUTHOR]

[Display omitted] • Polymeric silica-containing catalysts were developed for anthracene hydrocracking. • Two different methods for the polymer surface modification by silica were applied. • The catalysts are characterized by the high surface area, bimodal pore size distribution and high acidity. • The synthesized Ni-SiO 2 -MN-270 catalysts provide over 80 % of anthracene conversion into monoaromatics. In this work, novel bifunctional catalysts based on the polymeric network of hypercrosslinked polystyrene were developed for the process of anthracene hydrocracking in the medium of supercritical propanol-2. The synthesized catalysts contain NiOOH as an active phase and the SiO 2 as Brønsted acid sites supported on the highly porous support. The influence of the synthesis method and silica precursor type on the textural properties and the active phase composition was studied. The catalyst obtained by the hydrothermal method using tetraethoxysilane as a silica precursor seems to be the most optimal providing both high surface area, bimodal pore size distribution, and high acidity, and, thus, higher catalytic activity in anthracene hydrocracking. [ABSTRACT FROM AUTHOR]

[Display omitted] • Novel bimetallic Ru-Co polymeric catalysts were synthesized. • Hydrogenation of levulinic acid was studied at variation of reaction conditions. • Impregnation of Co resulted in Ru redistribution inside the polymeric support. Levulinic acid (LA) is one of the substances, which can be obtained from cellulosic biomass via acid hydrolysis and serves as a precursor in the synthesis of gamma-valerolactone (GVL) – platform chemical for so-called valeric fuels. This work is devoted to the study of catalytic conversion of LA to GVL using mono- (Ru) and bimetallic (Ru-Co) catalysts based on ruthenium-containing nanoparticles immobilized in hyper-crosslinked polystyrene (HPS). It was shown that RuO 2 nanoparticles are an active phase of HPS-based Ru catalysts, which allow nearly 100 % yield of GVL at 120 °C and 2 MPa of hydrogen partial pressure for the reaction time 60 min. Introduction of cobalt in catalyst composition in a proper amount (Ru-to-Co weight ratio is 30) was found to result in Ru redistribution inside the polymeric support and, in turn, to the increase of reaction rate of LA hydrogenation. [ABSTRACT FROM AUTHOR]

Here, the development of a new catalyst is reported for the selective furfural (FF) hydrogenation to furfuryl alcohol (FA) based on about 7 nm sized Pd−Cu alloy nanoparticles (NPs) formed in inexpensive, commercially available micro/mesoporous hypercrosslinked polystyrene (HPS). A comparison of the catalytic properties of as‐synthesized and reduced (denoted "r") catalysts as well as Pd−Cu alloy and monometallic palladium NPs showed a considerable enhancement of the catalytic performance of Pd−Cu/HPS‐r compared to other catalysts studied, resulting in about 100 % FF conversion, 95.2 % selectivity for FA and a TOF of 1209 h−1. This was attributed to the enrichment of the NP surface with copper atoms, disrupting the furan ring adsorption, and to the presence of both zerovalent and cationic palladium and copper species, resulting in optimal hydrogen and FF adsorption. These factors along with exceptional stability of the catalyst in ten consecutive catalytic cycles make it highly promising in practical applications. [ABSTRACT FROM AUTHOR]

In the current paper, the possibility of the use of magnetically separable catalysts containing ruthenium oxide species in the supercritical deoxygenation of stearic acid for producing of the second generation of biodiesel is reported. Three different supports (silica, ceria, and hypercrosslinked polystyrene) were used for the stabilization of magnetic nanoparticles (MNPs) and Ru-containing particles. The effect of support on the magnetic properties as well as the catalytic activity of the obtained systems was studied. All synthesized catalysts were shown to provide high stearic acid conversion (up to 95 %). The highest yield of C17+ hydrocarbons (up to 86 %) was observed while using the Ru–Fe3O4-HPS system. Ru–Fe3O4-HPS was characterized by the high values of the specific surface area (364 m2/g) and saturation magnetization (4.5 emu/g). The chosen catalytic system was found to maintain its catalytic activity for a minimum of 10 consecutive cycles. [ABSTRACT FROM AUTHOR]

Levulinic acid (LA) is a substance, which can be obtained from cellulosic biomass and hydrogenated to gamma-valerolactone (GVL) – important platform chemical. This work describes the study of a ruthenium-containing catalysts synthesized by the impregnation of HZSM-5 having different silicate modulus (40, 80 or 400) with ruthenium precursor, which resulted in formation of oxidized Ru(III) and Ru(IV) species on the catalyst surface. Synthesized catalysts allowed more than 98% of LA conversion for 60 min of the reaction and 100% GVL selectivity while working at relatively mild conditions (100 °C, 1 MPa of H 2) in aqueous medium. It was demonstrated that the observed catalytic activity mainly depends on two factors: (i) concentration of strong Lewis acid centers on the catalyst surface and (ii) surface content of RuO 2 , since the synthesized catalysts needed no preliminarily activation procedure. [Display omitted] • Novel Ru/HZSM-5 catalysts were synthesized. • Hydrogenation of levulinic acid was studied at variation of reaction conditions. • RuO 2 was catalytically active phase. • Zeolite acidity was responsible for the reaction acceleration. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Pd-containing nanoparticles were stabilized by hypercrosslinked polystyrene. • The structure and catalytic activity of Pd nanoparticles were found to be depended on the nature of the precursor. • Pd-containing nanoparticles stabilized by HPS showed high selectivity (more 85%) in the hydrogenation of FF to FA. Abstract We report the hydrogenation of furfural (FF) to furfuryl alcohol (FA) with Pd-containing catalysts stabilized by hypercrosslinked polystyrene (HPS). FF is one of the major ingredients of biooil produced by biomass pyrolysis, while FA is a source of value-added chemicals, thus, creating an effective path from biomass to important compounds. Different palladium precursors (PdCl 2 (CH 3 CN) 2 , Pd(CH 3 COO) 2) were used for the catalysts synthesis. The nature of the precursor influences the size of palladium nanoparticles. The TEM and SAXS data showed that when using PdCl 2 (CH 3 CN) 2 , a monomodal distribution of particles size with mean diameter 5.4 ± 1.2 nm was observed, whereas for Pd(CH 3 COO) 2 , multimodal particle size distribution with the mean particle sizes up to 13.8 ± 5.4 nm was observed. The comparison of the catalytic activities of Pd-containing catalysts indicated that the more disperse sample of palladium showed higher values of FF conversion and selectivity to FA because of small particles. [ABSTRACT FROM AUTHOR]

Deposition of catalytically active metal‐containing compounds on solid porous supports by using superheated (subcritical) water is a promising way to produce materials with unique physicochemical and catalytic properties. The hydrothermal method has been found to give catalysts with high surface area, fine distribution of the active phase, and high catalytic activity. In the current work, the catalytic activities of 10 % Ni and 10 % Co deposited on hyper‐cross‐linked polystyrene (HPS) by the hydrothermal method in the supercritical deoxygenation of fatty acids were compared. 10 % Ni/HPS was found to be the most active catalyst in the deoxygenation of stearic acid in supercritical n‐hexane. Supported metal catalysts play an important role in chemical technology, and hydrothermal synthesis of catalysts has recently attracted much attention. Cobalt and nickel nanoparticles were deposited on a hyper‐cross‐linked polystyrene matrix by a hydrothermal method, and the catalytic activity of the resulting catalysts was evaluated in the deoxygenation of fatty acids in supercritical n‐hexane. [ABSTRACT FROM AUTHOR]

The solubility of synthesis gas was measured in the temperature range of 100–300 °C and pressure range of 1.0–5.0 MPa in polar (2‐propanol) and nonpolar (n‐dodecane) solvents. Thermodynamic parameters of the absorption, such as the Henry constant, absorption enthalpy, and apparent activation energy of absorption, were calculated on the basis of the obtained results. The phase equilibrium was calculated by using the Soave‐Redlich‐Kwong cubic equation of state, which could be used to predict the optimal process conditions for liquid‐phase Fischer‐Tropsch reactions in different solvents. Solubilities of gases in liquids are needed to interpret rate data in gas‐liquid, gas‐liquid‐liquid, and gas‐liquid‐solid reactions. Hence, CO and H2 solubility under the conditions of liquid‐phase Fischer‐Tropsch synthesis were measured and thermodynamic parameters calculated. The SRK equation of state can be used to predict optimal process conditions for liquid‐phase Fischer‐Tropsch reactions. [ABSTRACT FROM AUTHOR]

In this report, three technological modes for methanol-to-gasoline reaction in the presence of H-ZSM-5 catalyst are compared: (i) direct methanol transformation to hydrocarbons; (ii) two-step (methanol-dimethyl ether-hydrocarbons); and (iii) cascade pathway. Light hydrocarbon gases (methane, ethylene, propylene, and isobutene) and liquid aromatic hydrocarbons (benzene, toluene, xylene, cresol, durol, naphthalene, methylnaphthalene, ethyl naphthalene, isopropyl naphthalene, methyl isopropyl naphthalene, etc.) were found to be the main reaction products. The experimental results showed that the classical two-step methanol to gasoline (MTG) process nowadays remains the most effective for gasoline-range hydrocarbons production, while one-step and cascade schemes require further investigation and the development of reactor systems as well as the operating conditions. The product distribution of MTG synthesis after 120 h on stream in the case of two-step mode was found to be the following: liquid C6-C8 hydrocarbons - 23%; C1-C5 gaseous products - 65%; heavy C9-C12 hydrocarbons - 10%. [ABSTRACT FROM AUTHOR]

Inulin is a naturally occurring polysaccharide, widely available as plant biomass. Here, we report utilization of a magnetically separable Ru-containing catalyst based on magnetic silica (Fe 3 O 4 -SiO 2 ) in the inulin hydrolytic hydrogenation to mannitol (a sweetener used in diabetic foods). The influence of the reaction parameters on the selectivity to mannitol has been studied. Under the optimal conditions the maximum selectivity to mannitol reached 44.3% at 100% conversion of the initial polysaccharide, exceeding that obtained with conventional Ru/C. The catalyst used in this work is stable under hydrothermal conditions of the process. It can be easily magnetically separated from the reaction mixture and reused without any loss of selectivity and activity, making this catalyst promising for practical applications in biomass conversion. [ABSTRACT FROM AUTHOR]

Abstract: Here, we report on the development of novel Cr‐containing magnetic oxide nanoparticles (NPs) as catalysts for a syngas‐to‐methanol reaction which constitutes a sustainable route to obtain value‐added chemicals. These NPs have been synthesized in a one‐pot reaction by thermal decomposition of Cr acetylacetonate and doping metal acetylacetonates (if used) in the reaction solution of preformed magnetite NPs stabilized by polyphenylquinoxaline. For all the samples, the NP surface is enriched with Cr. At the same time, the Cr species are finely dispersed in the magnetite phase. This exposes Cr catalytic species to reacting molecules and creates an intimate contact between Cr3+ and Fe3O4. As a result, the methanol productivity rate for the Cr‐containing magnetic oxide prepared with 0.5 mmol of the Cr precursor is approximately three orders of magnitude higher than that for the conventional Cu/ZnO/Al2O3 catalyst. Additional doping of this Cr‐containing magnetic oxide with small amounts of Ni or La leads to even higher catalytic activity (by 40–49%). [ABSTRACT FROM AUTHOR]

The study presents the results of cellulose hydrolytic hydrogenation process in subcritical water in the presence of Ru-containing catalysts based on hypercrosslinked polystyrene (HPS) MN-270 and its functionalized analogues: NH 2 -HPS (MN-100) and SO 3 H-HPS (MN-500). It was shown that the replacement of the traditional support (carbon) by HPS increases the yield of the main cellulose conversion products – polyols – important intermediates for the chemical industry. The catalysts were characterized using transmission electron microscopy (TEM), high resolution TEM, and porosity measurements. Catalytic studies demonstrated that the catalyst containing 1.0% Ru and based on MN-270 is the most active. The total yield of sorbitol and mannitol was 50% on the average at 85% cellulose conversion. [ABSTRACT FROM AUTHOR]

This paper is devoted to the production of second generation biodiesel via catalytic hydrodeoxygenation of fatty acids. Pd/C catalysts with different metal loading were used. The palladium catalysts were characterized using low-temperature nitrogen physisorption and X-ray photoelectron spectroscopy. It was revealed that the most active and selective catalyst was 1%-Pd/C which allowed reaching up 97.5% of selectivity (regarding to n-heptadecane) at 100% conversion of substrate. Moreover, the chosen catalyst is more preferable according to lower metal content that leads the decrease of the process cost. The analysis of the catalysts showed that 1%-Pd/C had the highest specific surface area compared with 5%- Pd/C. [ABSTRACT FROM AUTHOR]

Hydrogenation of levulinic acid (LA) obtained from cellulose biomass is a promising path for production of γ-valerolactone (GVL)—a component of biofuel. In this work, we developed Ru nanoparticle containing nanocomposites based on hyperbranched pyridylphenylene polymer, serving as multiligand and stabilizing matrix. The functionalization of the nanocomposite with sulfuric acid significantly enhances the activity of the catalyst in the selective hydrogenation of LA to GVL and allows the reaction to proceed under mild reaction conditions (100 °C, 2 MPa of H2) in water and low catalyst loading (0.016 mol.%) with a quantitative yield of GVL and selectivity up to 100%. The catalysts were successfully reused four times without a significant loss of activity. A comprehensive physicochemical characterization of the catalysts allowed us to assess structure-property relationships and to uncover an important role of the polymeric support in the efficient GVL synthesis. [ABSTRACT FROM AUTHOR]

This work addresses the Suzuki cross-coupling between 4-bromoanisole (BrAn) and phenylboronic acid (PBA) in an environmentally benign ethanol–water solvent catalysed by mono- (Pd) and bimetallic (PdAu, PdCu, PdZn) nanoparticles (NPs) stabilised within hyper-cross-linked polystyrene (HPS) bearing tertiary amino groups. Small Pd NPs of about 2 nm in diameters were formed and stabilized by HPS independently in the presence of other metals. High catalytic activity and complete conversion of BrAn was attained at low Pd loading. Introduction of Zn to the catalyst composition resulted in the formation of Pd/Zn/ZnO NPs, which demonstrated nearly double activity as compared to Pd/HPS. Bimetallic core-shell PdAu/HPS samples were 3-fold more active as compared to Pd/HPS. Both Pd/HPS and PdAu/HPS samples revealed promising stability confirmed by catalyst recycling in repeated reaction runs. [ABSTRACT FROM AUTHOR]

Here we report the functionalization of monodisperseiron oxidenanoparticles (NPs) with commercially available functional acids containingmultiple double bonds such as linolenic (LLA) and linoleic (LEA) acidsor pyridine moieties such as 6-methylpyridine-2-carboxylic acid, isonicotinicacid, 3-hydroxypicolinic acid, and 6-(1-piperidinyl)pyridine-3-carboxlicacid (PPCA). Both double bonds and pyridine groups can be reactedwith noble metal compounds to form catalytically active species inthe exterior of magnetic NPs, thus making them promising magneticallyrecoverable catalysts. We determined that both LLA and LEA stabilizemagnetic iron oxide NPs, allowing the formation of π-complexeswith bis(acetonitrile)dichloropalladium(II) in the NP shells. In bothcases, this leads to the formation of NP aggregates because of interparticlecomplexation. In the case of pyridine-containing ligands, only PPCAwith two N-containing rings is able to provide NP stabilization andfunctionalization whereas other pyridine-containing acids did nowallow sufficient steric stabilization. The interaction of PPCA-basedparticles with Pd acetate also leads to aggregation because of interparticleinteractions, but the aggregates that are formed are much smaller.Nevertheless, the catalytic properties in the selective hydrogenationof dimethylethynylcarbinol (DMEC) to dimethylvinylcarbinol were thebest for the catalyst based on LLA, demonstrating that the NP aggregatesin all cases are penetrable for DMEC. Easy magnetic separation ofthis catalyst from the reaction solution makes it promising as a magneticallyrecoverable catalyst. [ABSTRACT FROM AUTHOR]

Carbon-carbon cross-coupling reactions are among the most important synthetic tools for the preparation of pharmaceuticals and bioactive compounds. However, these reactions are normally carried out using copper, phosphines, and/or amines, which are poisonous for pharmaceuticals. The use of nanocomposite catalysts holds promise for facilitating these reactions and making them more environmentally friendly. In the present work, the PEGylated (PEG stands for poly(ethylene glycol) pyridylphenylene dendrons immobilized on silica loaded with magnetic nanoparticles have been successfully employed for the stabilization of Pd2+ complexes and Pd nanoparticles. The catalyst developed showed excellent catalytic activity in copper-free Sonogashira and Heck cross-coupling reactions. The reactions proceeded smoothly in green solvents at low palladium loading, resulting in high yields of cross-coupling products (from 80% to 97%) within short reaction times. The presence of magnetic nanoparticles allows easy magnetic separation for repeated use without a noticeable decrease of catalytic activity due to the strong stabilization of Pd species by rigid and bulky dendritic ligands. The PEG dendron periphery makes the catalyst hydrophilic and better suited for green solvents. The minor drop in activity upon the catalyst reuse is explained by the formation of Pd nanoparticles from the Pd2+ species during the catalytic reaction. The magnetic separation and reuse of the nanocomposite catalyst reduces the cost of target products as well as energy and material consumption and diminishes residual contamination by the catalyst. These factors as well as the absence of copper in the catalyst makeup pave the way for future applications of such catalysts in cross-coupling reactions. [ABSTRACT FROM AUTHOR]

Abstract: This paper reports deposition of ultrathin poly(sodium-4-styrenesulfonate)/chitosan layers on a mesoporous alumina surface and the formation of catalytic Pd nanoparticles in mesopores covered by such layers. The structure of these nanoparticulate catalysts has been studied using scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, N2 adsorption–desorption and CO chemisorption measurements. The Pd nanoparticles formed in the mesopores covered by ultrathin polymer layers do not exceed 2–3nm, revealing that these layers can control nucleation and growth of nanoparticles. The catalytic behavior of these catalysts has been investigated in selective hydrogenation of dehydrolinalool to linalool. The catalytic properties were found to depend on the amounts of poly(sodium-4-styrenesulfonate) and chitosan deposited on alumina, determining the nanoparticle coverage and formation of catalytic centers either before hydrogenation or in situ: the latter occurred when chitosan coverage was insufficient. High stability, low cost and exceptionally high catalytic activity, makes these catalysts promising candidates for broad catalytic applications. [Copyright &y& Elsevier]

This work is addressing the arenes' hydrogenation—the processes of high importance for petrochemical, chemical and pharmaceutical industries. Noble metal (Pd, Pt, Ru) nanoparticles (NPs) stabilized in hyper-cross-linked polystyrene (HPS) were shown to be active and selective catalysts in hydrogenation of a wide range of arenes (monocyclic, condensed, substituted, etc.) in a batch mode. HPS effectively stabilized metal NPs during hydrogenation in different medium (water, organic solvents) and allowed multiple catalyst reuses. [ABSTRACT FROM AUTHOR]

Here, we report the development of novel Ru-containing catalysts based on porous metal oxide supports such as SnO 2 , Nb 2 O 5 , and Nb 2 Sn 5 O 15. We assessed structure, porosity, acidity and morphology of both supports and catalysts and established a relationship between surface interactions and catalytic performance in hydrogenation of biomass based levulinic acid (LA) to γ-valerolactone (GVL). All metal oxide supports stabilize small Ru-containing nanoparticles (NPs), whose makeup includes a prevailing fraction of Ru(OH) 3. Yet, Nb 2 O 5 stabilizes ∼1 nm Ru-containing NPs which are homogeneously distributed on the metal oxide surface, while for SnO 2 and Nb 2 Sn 5 O 15 , sub-nanometer NPs are formed, which are prone to aggregation to minimize surface energy. These differences are assigned to nucleation of NPs on support oxygen vacancies, whose amounts vary and are consistent with NP characteristics. The catalytic testing shows that the 100 % conversion and selectivity as well as high turnover frequency are achieved for Ru/Nb 2 O 5 , whose surface morphology includes well-dispersed 1 nm Ru-containing NPs. These and high stability of catalytic performance upon multiple reuse, make Ru/Nb 2 O 5 promising for practical applications. Furthermore, this work validates the usefulness of surface interactions on metal oxides in development of efficient catalytic systems. [ABSTRACT FROM AUTHOR]