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Bifunctional catalysts consisting of metal-containing nanoparticles (NPs) and zeolite supports have received considerable attention due to their excellent catalytic properties in numerous reactions, including direct (biomass is a substrate) and indirect (platform chemical is a substrate) biomass processing. In this short review, we discuss major approaches to the preparation of NPs in zeolites, concentrating on methods that allow for the best interplay (synergy) between metal and acid sites, which is normally achieved for small NPs well-distributed through zeolite. We focus on the modification of zeolites to provide structural integrity and controlled acidity, which can be accomplished by the incorporation of certain metal ions or elements. The other modification avenue is the adjustment of zeolite morphology, including the creation of numerous defects for the NP entrapment and designed hierarchical porosity for improved mass transfer. In this review, we also provide examples of synergy between metal and acid sites and emphasize that without density functional theory calculations, many assumptions about the interactions between active sites remain unvalidated. Finally, we describe the most interesting examples of direct and indirect biomass (waste) processing for the last five years. [ABSTRACT FROM AUTHOR]

In recent years, Pd-containing catalytic systems for tandem processes have gained special attention due to their enhanced catalytic properties and their possibility of performing several reactions without the necessity of separating the intermediates. In this review, recent progress in Pd-catalyzed tandem processes is considered. Three types of catalytic systems are described: homogeneous catalysts (including immobilized Pd complexes); heterogeneous catalysts supported on oxides, MOFs, COFs, etc., with particular attention to the supports containing acid/base sites; and metal-enzyme catalysts for chemoenzymatic tandem processes applied in fine organic synthesis and biotechnology. For homogeneous Pd-catalyzed reactions, different tandem reactions were considered, i.e., cross-coupling, cyclization, carbonylation, isomerization, alkylation, arylation, etc. [ABSTRACT FROM AUTHOR]

Nanobiocatalysts, i.e., enzymes immobilized on nanostructured supports, received considerable attention because they are potential remedies to overcome shortcomings of traditional biocatalysts, such as low efficiency of mass transfer, instability during catalytic reactions, and possible deactivation. In this short review, we will analyze major aspects of immobilization of cellulase—an enzyme for cellulosic biomass waste processing—on nanostructured supports. Such supports provide high surface areas, increased enzyme loading, and a beneficial environment to enhance cellulase performance and its stability, leading to nanobiocatalysts for obtaining biofuels and value-added chemicals. Here, we will discuss such nanostructured supports as carbon nanotubes, polymer nanoparticles (NPs), nanohydrogels, nanofibers, silica NPs, hierarchical porous materials, magnetic NPs and their nanohybrids, based on publications of the last five years. The use of magnetic NPs is especially favorable due to easy separation and the nanobiocatalyst recovery for a repeated use. This review will discuss methods for cellulase immobilization, morphology of nanostructured supports, multienzyme systems as well as factors influencing the enzyme activity to achieve the highest conversion of cellulosic biowaste into fermentable sugars. We believe this review will allow for an enhanced understanding of such nanobiocatalysts and processes, allowing for the best solutions to major problems of sustainable biorefinery. [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]

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]

Fabrication of nanomaterials with a wealth of useful properties from renewable biomass such as plants, sea creatures, biomass waste, etc. received considerable attention of the broad scientific community which is reflected in an avalanche of publications. This path is economically and environmentally favorable, but is it possible to maintain a consistent structure and properties of target nanomaterials when raw materials are different, grown in different conditions, on different soils, etc.? Is it too good to be true? Is the nanomaterial preparation so robust that "minor" differences in the source materials do not matter? We believe these are important questions to be answered. Here we present a thorough and critical review of modern literature, focusing on finding relationships between the biomass origin and composition and the nanomaterial structure and performance. We analyze the variety of nanomaterials including carbon nanomaterials which are prepared by carbonization of various biomass sources as well as nanomaterials prepared by isolation of biomass components (cellulose, lignin, chitin). For each nanomaterial family, we establish crucial factors which determine their properties. [ABSTRACT FROM AUTHOR]

Abstract: In this paper we report the synthesis of robust and efficient nanocatalysts based on Pt-containing nanoparticles (NPs) formed in the pores of hypercrosslinked polystyrene (HPS) and their catalytic performance in the phenol CWAO under mild conditions. The Pt species were incorporated in HPS using wet impregnation of platinic acid in tetrahydrofuran followed by NaHCO3 treatment. The catalysts containing from 0.11 to 4.85wt.% of Pt were studied by X-ray fluorescence analysis, transmission electron microscopy, X-ray absorption spectroscopy, X-ray photoelectron spectroscopy, and liquid nitrogen physisorption methods. The NP sizes were found to be independent of the amount of platinic acid used for impregnation, but rather controlled by the pores of HPS. Three types of Pt species: Pt(0), Pt(II), and Pt(IV), constituted the NP composition. The effects of the phenol and catalyst initial concentrations and temperature were investigated in the phenol CWAO. Removal of 97% of the phenol with 94.2% selectivity to CO2 and H2O were observed for the most active catalyst containing 0.95wt.% Pt. These parameters are significantly higher than those for the conventional Al2O3–Pt catalyst with the similar amount of the active metal or for Pt(5%)/activated carbon. [Copyright &y& Elsevier]

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]

In this short review (Perspective), we identify key features of the performance of biocatalysts developed by the immobilization of enzymes on the supports containing magnetic nanoparticles (NPs), analyzing the scientific literature for the last five years. A clear advantage of magnetic supports is their easy separation due to the magnetic attraction between magnetic NPs and an external magnetic field, facilitating the biocatalyst reuse. This allows for savings of materials and energy in the biocatalytic process. Commonly, magnetic NPs are isolated from enzymes either by polymers, silica, or some other protective layer. However, in those cases when iron oxide NPs are in close proximity to the enzyme, the biocatalyst may display a fascinating behavior, allowing for synergy of the performance due to the enzyme-like properties shown in iron oxides. Another important parameter which is discussed in this review is the magnetic support porosity, especially in hierarchical porous supports. In the case of comparatively large pores, which can freely accommodate enzyme molecules without jeopardizing their conformation, the enzyme surface ordering may create an optimal crowding on the support, enhancing the biocatalytic performance. Other factors such as surface-modifying agents or special enzyme reactor designs can be also influential in the performance of magnetic NP based immobilized enzymes. [ABSTRACT FROM AUTHOR]

Here, we developed magnetically recoverable biocatalysts based on magnetite nanoparticles coated with an ultra-thin layer (about 0.9 nm) of chitosan (CS) ionically cross-linked by sodium tripolyphosphate (TPP). Excessive CS amounts were removed by multiple washings combined with magnetic separation. Glucose oxidase (GOx) was attached to the magnetic support via the interaction with N-hydroxysuccinimide (NHS) in the presence of carbodiimide (EDC) leading to a covalent amide bond. These steps result in the formation of the biocatalyst for D-glucose oxidation to D-gluconic acid to be used in the preparation of pharmaceuticals due to the benign character of the biocatalyst components. To choose the catalyst with the best catalytic performance, the amounts of CS, TPP, NHS, EDC, and GOx were varied. The optimal biocatalyst allowed for 100% relative catalytic activity. The immobilization of GOx and the magnetic character of the support prevents GOx and biocatalyst loss and allows for repeated use. [ABSTRACT FROM AUTHOR]

Horseradish root peroxidase biocatalysts can be used to oxidize various phenolic compounds. In this work, peroxidase was covalently immobilized on inorganic SiO2 and Al2O3 carriers and magnetic Fe3O4 nanoparticles. The latter were synthesized by the polyol method. For all biocatalytic systems, the effect of modifying and activating agents was evaluated. For each biocatalyst, the optimal composition was determined, at which the biocatalyst is most active. All samples were tested in the oxidation reaction of 2,3,6‐trimethylphenol using hydrogen peroxide as an oxidizing agent. It was found that a biocatalyst based on peroxidase immobilized on magnetic Fe3O4 nanoparticles showed the highest specific activity compared to the native form of the enzyme. Also, such a biocatalyst is easy to use due to the simplicity of its separation from the reaction mass. [ABSTRACT FROM AUTHOR]

This work is devoted to kinetic modelling of levulinic acid (LA) hydrogenation to gamma-valerolactone (GVL) in aqueous medium in a batch mode using 5%-Ru/MN100 catalyst, which comprises Ru dioxide nanoparticles confined in polymeric network of hyper-crosslinked polystyrene of MN100 type. Kinetic models of liquid-phase hydrogenation of LA to GVL were proposed based on Langmuir–Hinshelwood and Eley–Rideal mechanisms. Calculations based on experimental data obtained during the study allowed determining the main kinetic parameters of LA hydrogenation reaction and to propose the rate expression adequately describing the catalytic process. Moreover, hypothesis on the reaction mechanism was proposed considering RuO2 as catalytically active phase and 4-hydroxypentanoic acid as main intermediate compound. [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]

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]

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]

[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]

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]

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]

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]

Abstract Here we report immobilization of glucose oxidase (GOx) on magnetic silica (Fe 3 O 4 -SiO 2) and alumina (Fe 3 O 4 -Al 2 O 3) functionalized with amino groups using glutaraldehyde as a linker. Magnetic support based biocatalysts demonstrate high catalytic activity in d -glucose oxidation to D-gluconic acid at pH 5–7.5 and temperature of 30–50 °C with the best activities of 95% and 91% for magnetic silica and alumina, respectively. A comparison of magnetic and non-magnetic alumina and silica shows a significant enhancement of the relative catalytic activity for magnetic supports, while the silica based biocatalysts show a higher activity than the biocatalysts based on alumina. A noticeably higher activity of GOx immobilized on magnetic supports is explained by synergy of the GOx inherent activity and enzyme-like activity of iron oxide nanoparticles, while the enhancement with silica based catalysts is most likely due to a larger pore size and stronger Brønsted acid sites. Excellent relative activity of Fe 3 O 4 -SiO 2 -GOx (95% of native GOx) in a tolerant pH and temperature range as well as high stability in a repeated use (6% relative activity loss after five catalytic cycles) makes this catalyst promising for practical applications. Graphical abstract Unlabelled Image [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]

In this paper, the commercial 5%Pd/C and 5%Pt/C catalysts and synthesized 5%Pt/MN-270 and 5%Pd/MN-270 were used in the hydrogenolysis of lignocellulosic material (softwood sawdust) to obtain liquid fuels in the form of hydrocarbons. As lignin has a very complex structure, anisole was used as a model compound. It was found that the use Pt-containing catalysts based on hypercrosslinked polystyrene in both processes of anisole and lignin-containing feedstock conversion allowed obtaining the highest yield of oxygen-free hydrocarbons (up to 96 wt. %). Besides, the polymer based catalysts showed high stability in hydrogenolysis process in comparison with the commercial carbon based catalysts. [ABSTRACT FROM AUTHOR]

An approach for analysis of thermal gradients in a catalytic packed bed milli-reactor operated under radio frequency (RF) heating has been presented. A single-point temperature measurement would cause the misinterpretation of the catalytic activity in an RF-heated reactor, because of the presence of a temperature gradient. For reliable data interpretation, the temperature should be measured at three positions along the reactor length. The temperature profile can be accurately estimated with the exact analytical solution of a one-dimensional (1D) convection and conduction heat-transfer model, and it can also be approximated with a second-order polynomial function. The results revealed that the position of maximum temperature in the catalytic bed shifts toward a downstream location as the flow rate increases. The relative contribution of conduction and convection to the overall heat transport has been discussed. The design criteria for a near-isothermal milli-reactor have been suggested. [ABSTRACT FROM AUTHOR]

Here, we report the influence of the pore size in biocatalysts based on magnetically responsive mesoporous silicas on the loading of an immobilized enzyme - glucose oxidase (GOx) - and the activity and reusability of the biocatalyst in d -glucose oxidation. The choice of the silica supports was determined by their commercial availability and drastically different pores sizes: 6 nm and 15 nm. In the former case, the pores are too small to accommodate GOx whose hydrodynamic diameter is 7.6 nm, while in the latter case, there is an ample room for immobilization of GOx inside the pores. Magnetic properties in both cases were imparted by the formation of magnetite nanoparticles in silica pores, whose presence did not alter the pore size distribution. We demonstrate that larger pores allow for higher enzyme loading capacity due to immobilization inside the pores, remarkable 100% relative activity, and enhanced stability in the repeated use due the conformational integrity of GOx in spacious pores. This study unambiguously shows advantages of supports with pores larger than the size of an enzyme for its immobilization in the biocatalyst synthesis. [Display omitted] • Enzymes immobilized on porous magnetic supports possess key advantages. • 15 nm pores (larger than the enzyme size of 7.6 nm) allow higher loading capacity. • Relative activity of 100% in d -glucose oxidation is achieved for the 15 nm pore support. • The magnetically recoverable catalyst with large pores allows successful reusability. [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]

Kinetics of the selective hydrogenation of 2-methyl-3-butyn-2-ol (MBY) to 2-methyl-3-buten-2-ol (MBE) over Pd supported on hypercrosslinked polystyrene bearing amino-groups was studied at variation of the MBY-to-Pd ratio and reaction temperature. For the catalyst, containing 0.7 wt.% of Pd, optimal reaction conditions were found providing >98% of the MBE selectivity at 95% of the MBY conversion. Kinetic modeling and temperature variations as well as studies of a hydrogen consumption rate allowed us to suggest that a thermodynamic factor is most likely responsible for the high MBE selectivity. [ABSTRACT FROM AUTHOR]

Here, we report a one-pot solvothermal method for the development of magnetically recoverable catalysts with Ru or Ag nanoparticles (NPs) capped by chitosan (CS), a derivative of natural chitin. The formation of iron oxide NPs was carried out in situ in the presence of CS and iron acetylacetonate in boiling triethyleneglycol (TEG) due to CS solubilization in warm TEG. Coordination with Ru or Ag species and the NP formation take place in the same reaction solution, eliminating intermediate steps. In optimal conditions the method developed allows stabilization of 2.2 nm monodisperse Ru NPs (containing both Ru0 and Ru4+ species) that are evenly distributed through the catalyst, while for Ag NPs, this stabilizing medium is inferior, leading to exceptionally large Ag nanocrystals. Catalytic testing of CS-Ru magnetically recoverable catalysts in the reduction of 4-nitrophenol to 4-aminophenol with excess NaBH 4 revealed that the catalyst with 2.2 nm Ru NPs exhibits the highest catalytic activity compared to samples with larger Ru NPs (2.9–3.2 nm). Moreover, this catalyst displayed extraordinary shelf-life in the aqueous solution (up to ten months) and excellent reusability in ten consecutive reactions with easy magnetic separation at each step which were assigned to its conformational rigidity at a constant pH. These characteristics as well as favorable environmental factors of the catalyst fabrication, make it promising for nitroarene reduction. [Display omitted] • Chitosan (CS) stabilizes magnetic and catalytic nanoparticles in one-pot procedure. • CS dissolves in warm triethylene glycol - green solvent. • CS-Fe 3 O 4 -Ru(Ag) displays catalytic activity in 4-nitrophenol reduction. • CS-Fe 3 O 4 -Ru exhibits extraordinary shelf-life in the aqueous solution. • The CS based catalyst shows excellent reusability in ten consecutive reactions. [ABSTRACT FROM AUTHOR]

The kinetics of d-glucosehydrogenation on the catalystcontaining Ru nanoparticles in the matrix of hypercrosslinked polystyrenewas studied. Two routes of the hydrogenation reaction were revealed;their rates differ by several digits. The first route includes theinteraction of d-glucose with the spilled-over hydrogen suppliedby the catalyst; the second one includes classical interaction ofthe sorbed substrate with incident hydrogen from the reaction medium.A mathematical description of d-glucose conversion and thechange of the catalyst activity by the first method of d-glucosehydrogenation were obtained. The most probable scheme of the processflow was suggested. The main kinetic parameters were calculated. Therole of hydrogen spillover phenomenon in the kinetics of the processesis discussed. [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]

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]

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]

Postimpregnation of Pd nanoparticles (NPs) stabilized within hyper-cross-linked polystyrene with sodium or potassium hydroxides of optimal concentration was found to significantly increase the catalytic activity for the partial hydrogenation of the C-C triple bond in 2-methyl-3-butyn-2-ol at ambient hydrogen pressure. The alkali metal hydroxide accelerates the transformation of the residual Pd(II) salt into Pd(0) NPs and diminishes the reaction induction period. In addition, the selectivity to the desired 2-methyl-3-buten-2-ol increases with the K- and Na-doped catalysts from 97.0 up to 99.5%. This effect was assigned to interactions of the alkali metal ions with the Pd NPs surfaces resulting in the sites' separation and a change of reactants adsorption. [ABSTRACT FROM AUTHOR]