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Liquid fuel production from biomass-derived molecules has received great attention due to the diminished fossil fuel reserves, growing energy demand, and the necessity of CO2 emission reduction. The deoxygenation of oils and fatty acids is a promising process to obtain "green" diesel. Herein, we report the results of the study of the deoxygenation of stearic acid to alkanes as a model reaction. Series of Ni-supported on schungite were obtained by precipitation in subcritical water (hydrothermal deposition) and for comparison via wetness impregnation followed, in both cases, by calcination at 500 °C and a reduction in H2 at 300 °C. The catalyst obtained via hydrothermal synthesis showed a three-fold higher specific surface area with a four-fold higher active phase dispersion compared to the catalysts synthesized via conventional impregnation. The catalysts were tested in stearic acid deoxygenation in supercritical n-hexane as the solvent. Under optimized process conditions (temperature of 280 °C, hydrogen partial pressure of 1.5 MPa, and 13.2 mol of stearic acid per mol of Ni), a close to 100% yield of C10–C18 alkanes, containing over 70 wt.% of targeted n-heptadecane, was obtained after 60 min of reaction. [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]

Biocatalysts based on magnetically responsive supports and the immobilized enzyme - cellulase- demonstrated the high activity in the carboxymethylcellulose (CMC) hydrolysis. Magnetic supports were obtained by two ways: (i) the synthesis of magnetite nanoparticles (NPs) followed by silica shell coating, (ii) the form magnetite NPs by crystallization ones in the pores of mesoporous silica. Physico-chemical methods (low-temperature nitrogen adsorption, scanning electron microscopy, electron-transparent specimens for transmission electron microscopy and magnetic measurements) were utilized for characterization of the structure and surface of the obtained magnetic support. The loading of the enzyme on magnetic supports of both types was approximately the same and amounted to 75-78 %. Cellulase immobilized on magnetic mesoporous silica (SiO2@Fe3O4@CEL) showed 87 % activity of the free enzyme. The scientific novelty of this work is that the controlled pore size in the mesopore range allows bulky enzyme molecules to be immobilized. The large surface area improves catalytic efficiency by increasing enzyme loading and finely dispersing biocatalyst molecules. The limiting effect of mesopores can improve the stability of the enzyme and its resistance to extreme pH and temperature. However, the use of immobilized cellulase may be limited due to the efficiency of the regeneration process. As a solution to this problem, the use of magnetic nanoparticles incorporated into a mesoporous silica matrix is proposed. The magnetic nanobiocatalyst can be easily removed from the reaction mixture using an external magnet. [ABSTRACT FROM AUTHOR]

In this work, we propose a procedure for the synthesis of magnetic materials based on commercial zeolites of the ZSM-5 type and the oxide form of aluminosilicate SIRALOX 40/490. The synthesized composites were characterized by various physicochemical methods. In particular, it was shown for the first time that the introduction of magnetite nanoparticles into aluminosilicate sorbents results in the blocking of acid sites. It has been established that the specific surface area and the nature of the porosity of the initial sorbents do not undergo critical changes in the course of synthesis, which also suggests a slight change in their sorption properties. Using electron microscopy, the average size of magnetite particles formed in the pores of sorbents was determined to be within 55-65 nm. The high content of iron in composites (in the composition of magnetite) determines their good magnetic characteristics, which allows them to be quickly and completely separated from the liquid phase by means of an external magnetic field. The synthesized magnetic composites can be used as sorbents or supports for the synthesis of magnetically recoverable heterogeneous catalytic systems, which can significantly reduce the cost and facilitate the regeneration and reuse procedure. [ABSTRACT FROM AUTHOR]

A cascade reaction is defined as the chemical process which consists of two or more consecutive reactions carried out in the same reaction vessel due to the multifunctionality of the catalyst. This approach was utilized by researchers to design advanced biocatalysts with two or more enzymes immobilized on the same support. The key benefits of multienzyme biocatalysts rise from a single pot, where consecutive reactions are performed, thus eradicating the handling of intermediate products. This makes processes more sustainable, allowing one to obtain target molecules in a more environmentally friendly way. We report on the effect of pore size in biocatalysts based on mesoporous silica on the loading of immobilized enzymes glucose oxidase (GOx) and horseradish peroxidase (HRP) as well as on the activity and the possibility of reuse of the bio-enzyme biocatalyst in a cascade reaction. The choice of silica substrates was due to their commercial availability and sharply different pore sizes: 6 nm and 15 nm. In the first case, the pores are too small to accommodate GOx and HRP, the hydrodynamic diameter of which is ~ 8 nm for each, while in the second case, there is enough space for immobilization of GOx and HRP inside the pores. We demonstrate that larger pores provide higher enzyme throughput due to immobilization within the pores, remarkable 95% relative activity, and increased stability during reuse due to the conformational integrity of GOx and HRP in spacious pores. This study clearly shows the advantages of substrates with pores larger than the size of the enzyme for its immobilization during the synthesis of the biocatalyst. [ABSTRACT FROM AUTHOR]

The work is devoted to the chemical modification of the natural chitosan polymer to improve its quality and suitability for further use in chemical processes. Chitosan samples with an increased degree of deacetylation and a reduced molecular weight were synthesized by the purification with sodium hydroxide with subsequent re-precipitation. Additionally, the chitosan succinate, chitosan hydrochloride, and thyoled chitosan were obtained. These compounds are characterized by solubility in a wider pH range compared to the commercially available samples. For each of the synthesized samples, infrared diffusion reflection spectra were obtained. The modified samples of chitosan were used for obtaining nanoparticles and finely-dispersed films. [ABSTRACT FROM AUTHOR]

This work is devoted to the investigation of the possibility of the use of Ru-containing catalysts on the basis of polymeric matrix of hypercrosslinked polystyrene (HPS) in the hydrogenation of levulinic acid (LA) to gamma-valerolactone (GVL). HPS-based Ru-containing catalysts were synthesized at variation of HPS type (MN100 bearing amino groups or MN270 without functional groups) and metal content. Catalyst 5%-Ru/MN100 was shown to compete with commercial 5%-Ru/C and to allow carrying out the hydrogenation of LA in aqueous medium with high yields of GVL (more than 99%).

The current work is devoted to the second-generation biodiesel production via fatty acids catalytic hydrodeoxygenation (HDO). Pd-containing catalysts based on polymeric matrix of hypercrosslinked polystyrene (HPS) with different metal loading were investigated in the process. The catalysts were characterized by low-temperature nitrogen physisorption, transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The selectivity of the process (regarding to n-heptadecane) reached up to 99% at 100% conversion. The optimal reaction conditions which allowed achieving high selectivity at 100% of stearic acid conversion were chosen.

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]

This paper reports palladium (Pd)-containing nanoparticle (NP) formation in nanoporous hypercrosslinked polystyrene (HPS), using Pd acetate as a precursor. It was demonstrated that the NP size and composition can be controlled by Pd acetate loading and post-impregnation treatment with hydrogen gas. The catalyst structure was studied using transmission electron microscopy (TEM), X-ray fluorescence analysis, X-ray photoelectron spectroscopy (XPS) and nitrogen physisorption measurements. The catalytic properties of the catalysts developed have been studied in a green process of D-glucose oxidation to D-gluconic acid. The latter and its Ca salt are used for pharmaceuticals and food supplement production. The most active catalyst was found to contain 1.7 nm Pd/PdO NPs at 1.09 wt% Pd loading. It provided 99.6% selectivity at 93.6% conversion. Repeated use of the same catalyst demonstrated exceptional stability in D-glucose oxidation, making these catalysts promising for industrial applications in sustainable processes.

The integration of biofuel upgrading processes in the existing technologies of crude oil refining is considered to be one of the promising directions for the production of liquid motor fuels. In this work, the co-processing of bio-oil obtained from biomass waste and heavy oil fractions in the supercritical solvent was studied. The bio-oil was obtained by the slow pyrolysis of birch and pine wood sawdust in the presence of a Fe-containing zeolitebased catalyst. The influence of the catalyst on the yield and composition of liquid products was studied. To find the optimal reaction conditions, the co-processing of the model compounds (anisole - eicosane - dibenzothiophene) was carried out by varying the solvent, reaction temperature, and the initial nitrogen pressure. Full removal of oxygen and sulfur as well as a decrease in the concentration of heavy and polyaromatic compounds from the feedstock were observed under the following process parameters: solvent - propanol-2, reaction temperature - 260 °C, initial nitrogen pressure - 1.5 MPa, total pressure - 7.2 MPa. [ABSTRACT FROM AUTHOR]

In this study, magnetic nanoparticles Fe3O4 synthesized by the polyol method were used to immobilize Horseradish root peroxidase. The surface of magnetic nanoparticles was pretreated with tetra-ethyl orthosilicate, 3-aminopropyltriethoxysilane, and glutaraldehyde. As a result, two biocatalysts were obtained Fe3O4/APTS/GA/HRP and Fe3O4/TEOS/APTS/GA/HRP. The activity of the synthesized biocatalysts was estimated spectrophotometrically in the oxidation reaction of 2,2'-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS) with hydrogen peroxide. The optimal conditions for this reaction were selected (pH 6.0, temperature 45 °C). It has been determined that biocatalysts Fe3O4/APTS/GA/HRP and Fe3O4/TEOS/APTS/GA/HRP slightly decreased their activity during 5 consecutive experiments, by 19 and 15 %. [ABSTRACT FROM AUTHOR]

Mesoporous silica, alumina and zirconia, were utilized as appropriate support for the formation of magnetite nanoparticles by in-situ crystallization and GOx immobilization. Magnetic and nonmagnetic supports were functionalized with amino groups and using glutaraldehyde as a linker. A comparative study showed that the nature of the carrier and the presence of magnetite nanoparticles all affect the catalytic properties of biocatalysts and their stability. Biocatalysts based on immobilized glucose oxidase demonstrated high catalytic activity (preservation of the activity of the free enzyme up to 98 %) and stability in D-glucose oxidation to Dgluconic acid at pH 4-8 and temperature of 30-60 °C. [ABSTRACT FROM AUTHOR]

Levulinic acid (LA) is a substance, which can be obtained from cellulosic biomass via acid hydrolysis. Hydrogenation of LA to gamma-valerolactone (GVL) is one of the most promising reactions in the field of biomass valorization to fine chemicals and liquid transportation fuels. In this work, the reaction of LA hydrogenation to GVL was carried out using series of Ru-containing catalytic systems based on zeolites (HZSM-5, HBeta, HY, HMordenite). It was shown that synthesized catalyst based on zeolite HZSM-5, containing RuO2 as an active phase, can provide high yields of GVL (up to 98 %) for less than 1 h upon relatively mild reaction conditions (100 °C, 1 MPa). Moreover, it was shown that the observed catalytic activity and stability depends on the concentration of RuO2 on the catalyst surface as well as on distribution of catalytically active phase. [ABSTRACT FROM AUTHOR]

Nowadays, the processes for the conversion of biomass to fuels are of great interest. One of the widely studied reactions is the deoxygenation of oxygen-containing compounds. The process is performed in two main directions: in hydrogen presence (namely hydrodeoxygenation) and using supercritical fluids as a hydrogen source. The modern problem in deoxygenation is catalyst stability and selectivity. Thus, the development of novel catalytic systems is an urgent task. Schungite is a natural carbon-reach material that has high sorption ability and excellent reductive properties. These properties make this material suitable for its use as catalyst support. In this work, the study of the effectiveness of novel schungite-based catalysts in supercritical deoxygenation of fatty acids and bio-oil model compounds is presented. The catalyst synthesis was performed by the recently developed method of Ni hydrothermal deposition on the schungite surface. The synthesized catalysts were tested in the deoxygenation of stearic acid and guayacol in the supercritical hexane. The experimental results showed that the developed catalysts allow 100 % conversion of the substrate to be reached in both processes providing over 90 wt.% of gasoline and diesel-range hydrocarbon yield. [ABSTRACT FROM AUTHOR]

Nitrobenzene hydrogenation is a widely used process applied for aniline production. Nitrobenzene hydrogenation kinetics greatly depends on catalyst properties and structure therefore, its study can shed light on process particularities and catalyst properties. The article is devoted to study of nitrobenzene hydrogenation kinetics for monometallic Ni (18.4 wt.%) containing hypercrosslinked polystyrene and bimetallic Pd(0.5 wt.%), Ni(17.9 wt.%) containing hypercrosslinked polystyrene. Nitrobenzene concentration and hydrogen partial pressure influence was studied in a variety of conditions. Nitrobenzene hydrogenation over monometallic sample shows the formation of essential amounts of side products - nitrozobenzene and phenylhydroxylamine while for bimetallic sample direct formation of aniline was noticed. Langmuir-- Hinshelwood model was used to study reaction kinetics. A complex model including azobenzene, phenylhydrohylamine and aniline formation steps was developed for monometallic catalyst. The reaction model for bimetallic Ni, Pd catalyst contains only direct aniline formation reaction due to high process selectivity. Values of adsorption and reaction constants are higher for bimetallic catalyst that can explain its enhanced nitrobenzene hydrogenation rate. [ABSTRACT FROM AUTHOR]

The study investigates the formation of Pt nanoparticles within a micro/macroporous hyper-cross-linked polystyrene (HPS) matrix in regard to the direct catalytic oxidation of L-sorbose to 2-keto-L-gulonic acids. It examines the structural characteristics of the nanoparticles at different stages of the reaction using a combination of X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), X-ray diffraction (XRD), and anomalous small-angle X-ray scattering (ASAXS).

In the current work, the synthesis of the effective multicomponent biocatalysts on the base of horseradish peroxidase immobilized on the modified titanium dioxide for the utilization of chlorophenolic water contaminants was performed. The influence of the support modification methods on the biocatalyst activity and stability was studied. The immobilization of horseradish peroxidase on the unmodified titanium dioxide was found to be ineffective due to the high losses in the enzyme amount during the reaction as well as the biocatalyst particles aggregation (the activity reduces more than 95%). The titanium dioxide surface modification by the sodium alginate and carbodiimide (23.5% activity in comparison with the native enzyme); hydrochloric acid, chitosan and glutaric dialdehyde (33.7% activity in comparison with the native enzyme); and hydrochloric acid, chitosan, glutaric dialdehyde and aminopropyltriethoxysilane (42.5% activity in comparison with the native enzyme) were found to be the most effective methods. Besides, the last two biocatalysts showed high stability in 10 consecutive cycles. The synthesized biocatalyst can be effectively used for the removal of chlorophenols from the wastewater until the concentrations of 10 ppm. [ABSTRACT FROM AUTHOR]

The search of the novel stable and active catalysts for the Fischer-Tropsch synthesis aimed at the formation of gasoline-range hydrocarbons is one of the main directions for the production of liquid transportation fuels from the alternative feedstock. The stabilization of the active phase is one of the key challenges for the development of the catalysts of CO hydrogenation into liquid motor fuel. This problem can be solved by the choice of optimal support as well as the method of synthesis. The rigid polymeric matrices allow obtaining highly effective and stable metal-containing nanoparticles characterized by the high surface area and enhanced activity. A hydrothermal deposition is a promising way to produce catalysts with the high dispersion of the active phase avoiding the pore blockage by the metal-containing particles. The current work is devoted to the development of novel polymer-based mono- and bimetallic Co-, Ni-, and Ru-containing nanocatalysts for the liquid-phase Fischer-Tropsch synthesis. It was shown that 1% Ru-HPS and 10% Co-1% Ru-HPS allow obtaining a high yield of gasoline-range C5-C9 hydrocarbons (over 70%) providing high CO conversion (up to 23%). The chosen polymer-based systems showed high stability in the FTS process. The activity loss was found to be insignificant for both catalysts (3.2% for 1% Ru-HPS, and 8.2% for 10% Co-1% Ru-HPS) after 20 h of the process. [ABSTRACT FROM AUTHOR]

The work is devoted to the modification of H-ZSM-5 samples with sodium hydroxide and oxalic acid to provide the formation of the mesoporous structure of the zeolite and to obtain optimal Si/Al ratio. Moreover, zeolite active sites were modified with Co, Ni, Fe in order to decrease polyaromatic substances formation during methanol transformation into hydrocarbons. The testing of the samples was performed at 350 °C in a flow reactor, the methanol feed rate was maintained at 0.16 g(methanol)/(g(Cat)*h). Dimethyl ether transformation rate into hydrocarbons was found to be 0.055-0.1 kg(DME)/(kg(Cat)*h) for investigated catalysts. Alkali treatment of H-ZSM-5 samples results in the formation of a mesoporous structure with a mean pore diameter of 5 nm. Formation of additional mesopores results in some increase of dimethyl ether to hydrocarbons transformation rate up to 0.09 kg(DME)/(kg(Cat)*h). Zeolite treatment with oxalic acid results in decreasing of Si/Al ratio from 0.76 to 0.41 that case some decrease of dimethyl ether transformation rate from 0.07 kg(DME)/(kg(Cat)*h) to 0.05 kg(DME)/(kg(Cat)*h), however considerable decrease of polyaromatic hydrocarbons concentration in reaction media was achieved for sample with lowest Si/Al ratio. Modification of H-ZSM-5 with Co, Fe, Ni results in some increase of dimethyl ether transformation rate up to 0.07-0.1 kg(DME)/(kg(Cat)*h) and a considerable decrease of polyaromatic hydrocarbons concentration in reaction media due to active sites modification. The ZSM-5-Ni-0.001M sample showed highest activity 0.1 kg(DME)/(kg(Cat)*h). [ABSTRACT FROM AUTHOR]

The aim of this work is to develop the synthesis of the magnetically separable biocatalyst for enzymatic oxidation of D-glucose to D-gluconic acid with high product yields. The biocatalyst support is based on magnetite particles (MPs) synthesized by coprecipitation and coated with the amino-silica layer to facilitate further functionalization. This functionalization involves the attachment of the glutaric dialdehyde linker followed by the covalent attachment of glucose oxidase (GOx, an enzyme of oxidoreductase group) via its amino groups. TEM, XRD, and magnetic measurements were performed for initial MPs and GOx biocatalyst. The biocatalyst activity was studied in the oxidation reaction of D-glucose to D-gluconic acid. The biocatalyst synthesis proposed in this work allowed to create a highly effective system. It was found that GOx immobilized on the modified MPs was the most active biocatalytic system in comparison with other inorganic support and showing 88% of gluconic acid yield. [ABSTRACT FROM AUTHOR]

Here, the novel method for the conversion of fatty acids into hydrocarbon fuel without hydrogen consumption is reported. The deoxygenation of stearic acid as a model compound was performed in the medium of supercritical n-hexane in the presence of Ni-containing catalysts synthesized by a hydrothermal deposition method. We studied the influence of the support as well as the metal loading on the yield of target products of stearic acid conversion into hydrocarbons. Ni was supported on the three different supports: anhydrous microporous silica, anhydrous alumina, and non-functionalized hypercrosslinked polystyrene. The hydrothermal synthesis of the catalysts leads to the changes in the porosity and structure of the supports increasing the number of mesopores. The active phase of the catalysts was found to be deposited on the internal surface of the supports as a thin layer of γ-NiOOH. Ni/HPS catalyst was found to be the most active in the stearic acid deoxygenation process in supercritical n-hexane. The study of the influence of the metal loading on the conversion of the substrate and the target product yield showed that 10 wt. % of Ni is more favorable for the production of high yield of C16-C17 hydrocarbons. [ABSTRACT FROM AUTHOR]

In this paper, a novel catalysts on the base of hypercrosslinked polystyrene (HPS) with magnetic properties are proposed for the one-pot processes of the cellulose conversion into ethylene glycol (EG) and propylene glycol (PG). Synthesized magnetically recoverable supports and catalysts were characterized by different physical-chemical methods. The magnetic properties of the supports Fe3O4/HPS MN270 and the corresponding catalysts were studied. The use of this catalyst in the process of microcrystalline cellulose hydrogenolysis in subcritical water allows PG and EG selectivities of 20.0 and 22.6%, respectively, at 100% of cellulose conversion. [ABSTRACT FROM AUTHOR]