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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%).

Selective oxidation of alcohols to the carboxylic acid plays an important role in the production of valuable chemicals. Herein, NiCo hydroxide (NiCo(OOH)x) nanosheets with a thickness of ~4 nm were controllably fabricated in a facile way efficient for the electrooxidation of benzyl alcohol (BAL) to benzoic acid (BAD). Mechanistic studies confirmed the hydroxyl active intermediate (OH*) generated on the surface of NiCo(OOH)x nanosheets through operando electrochemical impedance spectroscopy and the electron paramagnetic resonance spectroscopy analysis during the electrooxidation process. Importantly, we discovered that the OH* was crucial to boost the selective oxidation of BAL by attacking the hydroxyl end group to achieve carboxylic acid. The early onset potential of 1.16 VRHE in the presence of BAL was below 1.23 VRHE for oxygen evolution reaction. The rotating ring‐disk electrode further revealed that the electrocatalytic BAL oxidation reaction occurred earlier in the oxygen evolution reaction. In 150 mM BAL, NiCo(OOH)x nanosheets generated a high BAD selectivity of >99% and full conversion of BAL in 3 h. The experimental and theoretical calculation revealed that the dominant pathway of BAL oxidation was the interaction between nucleophilic BAL with OH* to form BAL‐OH* directly by dehydrogenates, thereby producing BAD with high efficiency. This research sheds mechanism insights on the electrocatalytic alcohols oxidation reaction. [ABSTRACT FROM AUTHOR]

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]

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]