Papers by Vladimir Vinokurov
Catalysts
The oxidative dehydrogenation of alkanes is a prospective method for olefins production. CO2-assi... more The oxidative dehydrogenation of alkanes is a prospective method for olefins production. CO2-assisted propane dehydrogenation over metal oxide catalysts provides an opportunity to increase propylene production with collateral CO2 utilization. We prepared the chromia catalysts on various mesoporous aluminosilicate supports, such as halloysite nanotubes, nanostructured core/shell composites of MCM-41/halloysite (halloysite nanotubes for the core; silica of MCM-41-type for the shell), and MCM-41@halloysite (silica of MCM-41-type for the core; halloysite nanotubes for the shell). The catalysts have been characterized by X-ray fluorescence analysis, low-temperature nitrogen adsorption, X-ray diffraction, temperature-programmed reduction, temperature-programmed desorption of ammonia, transmission electron microscopy with energy-dispersive X-ray spectroscopy, and thermogravimetric analysis. The catalysts’ performance in carbon-dioxide-assisted propane dehydrogenation has been estimated in ...
Progress in Organic Coatings, 2020
Micro/nanocontainer-based self-healing coatings have achieved enormous interest in scientific com... more Micro/nanocontainer-based self-healing coatings have achieved enormous interest in scientific community during the last decade. However, the search for multifunctional micro/nanocontainers still has research challenge, especially for the micro/nanocontainers with dual functionality (both anticorrosion and antimicrobial). Here, a novel type of microcapsules with antimicrobial shell and anticorrosion core was prepared by the Pickering emulsion polymerization technique. Dimethyloctadecyl [3-(trimethoxysilyl) propyl] ammonium chloride (QC18) and linseed oil were encapsulated as the antimicrobial and the anticorrosion agents, respectively. The results of local electrochemical impedance spectroscopy (LEIS) at 10 Hz demonstrated corrosion suppression in the scratched area of coatings doped with multifunctional microcapsules. Additionally, the QC18-modified microcapsules exhibited high antibacterial performance, showing over 90 % antimicrobial efficacy against grampositive bacteria. This type of dual-functional coating might guide future design of micro/nanocontainer-based self-healing paint formulations.
Science and Technology of Advanced Materials, 2022
ABSTRACT Following nanoarchitectural approach, mesoporous halloysite nanotubes with internal surf... more ABSTRACT Following nanoarchitectural approach, mesoporous halloysite nanotubes with internal surface composed of alumina were loaded with 5–6 nm RuCo nanoparticles by sequential loading/reduction procedure. Ruthenium nanoclusters were loaded inside clay tube by microwave-assisted method followed by cobalt ions electrostatic attraction to ruthenium during wetness impregnation step. Developed nanoreactors with bimetallic RuCo nanoparticles were investigated as catalysts for the Fischer-Tropsch process. The catalyst with 14.3 wt.% of Co and 0.15 wt.% of Ru showed high activity (СO conversion reached 24.6%), low selectivity to methane (11.9%), CO2 (0.3%), selectivity to C5+ hydrocarbons of 79.1% and chain growth index (α) = 0.853. Proposed nanoreactors showed better selectivity to target products combined with high activity in comparison to the similar bimetallic systems supported on synthetic porous materials. It was shown that reducing agent (NaBH4 or H2) used to obtain Ru nanoclusters at first synthesis step played a very important role in the reducibility and selectivity of resulting RuCo catalysts.
Advanced Functional Materials, 2021
One of the main challenges in modern tissue engineering is to design biocompatible scaffolds with... more One of the main challenges in modern tissue engineering is to design biocompatible scaffolds with finely tuned porous architecture and capacity to load bioactive molecules that guide the growth and differentiation of the cells during tissue reconstruction. This work proposes a strategy to design porous alginate scaffolds (PAS) with well-tuned architecture by leaching of sacrificial vaterite CaCO 3 microspheres packed in alginate. Pore size and interconnectivity depend on CaCO 3 sphere dimensions and packing as well as alginate concentration. Varying of these parameters, almost hundred percent pore interconnectivity (or, by contrast, a zero pore interconnectivity) can be achieved. Junctions between interconnected pores are about 50-70% of the pore dimensions that provides molecular transport through the PASs potentially ensuring diffusion of nutrition, oxygen and metabolic products when cell seeding. An opportunity to fabricate a multifunctional scaffold is demonstrated by encapsulation of desired macromolecules into the individual pores of a scaffold (is illustrated by dextran loading). Mechanical properties of PASs are found typical for soft and hydrated structures (Young's modulus of 19 ± 15 kPa) which is appropriate for cell seeding. The three cell lines (HeLa, HEK293, and L929) are cultured on different alginate scaffolds to examine cell viability and adhesiveness.
ACS Applied Nano Materials, 2021
Cellulose has a complex structure that seriously hinders its processing. Ionic liquids (ILs) have... more Cellulose has a complex structure that seriously hinders its processing. Ionic liquids (ILs) have the ability to dissolve cellulose, thus modifying its structure. A series of acetateand formate-based ILs was synthesized from their chloride analogues and tested for dissolution of microcrystalline cellulose. Cellulose solubility in 1-butyl-3-methylimidazolium acetate [BMIm]Ac, 1-ethyl-3-methylimidazolium acetate [EMIM]Ac, 1-butyl-3-methylimidazolium chloride [BMIm]Cl, 1-ethyl-3-methylimidazolium chloride [EMIM]Cl and their mixtures was investigated. The optimal weight ratio of a chloride-based IL to an acetate-based IL was found to be 3:2. The solubilizing power of that mixture was maximal, while that of butyl-substituted ILs exceeds the solubilizing power of individual compounds. Despite having better solvent power, acetate-based ILs provide a lower decrease in cellulose crystallinity, as revealed by powder X-ray diffraction studies, in comparison with their chloride-based counterpar...
Materials Letters, 2021
Abstract Au nanoparticles were loaded into halloysite nanotubes by freezing-induced loading metho... more Abstract Au nanoparticles were loaded into halloysite nanotubes by freezing-induced loading method. The loading efficiency and Au nanoparticle distribution were studied by UV-Vis absorption spectroscopy and transmission electron microscopy and compared to those of vacuum impregnation and adsorption from solution loading methods. The freezing-induced loading was found to be the most effective with the loading efficiency up to 85% after 5 loading cycles and the best Au nanoparticle distribution into halloysite nanotubes.
ACS Omega, 2021
Applying the eutectic hydrated salt (EHS) mixture of Na 2 HPO 4 •12H 2 O and Na 2 SO 4 •10H 2 O i... more Applying the eutectic hydrated salt (EHS) mixture of Na 2 HPO 4 •12H 2 O and Na 2 SO 4 •10H 2 O in a 1:1 weight ratio as a phase-change material and natural sepiolite nanocarriers as a matrix, the form-stable phase-change composite EHS@sepiolite was fabricated by vacuum impregnation. Due to the high porosity of sepiolite and its nanofibrous structure with internal channels, the effective loading of the phase-change material reached as high as 88 wt %. The melting temperature of the composite was 38.1°C and its melting enthalpy was 185 J g −1. The crystallinity of the hydrated salt mixture was retained after loading into the sepiolite matrix. The composite demonstrated high stability over 50 heat uptake/ release cycles maintaining its melting temperature and melting enthalpy the same. The combination of natural sepiolite nanocarriers and crystallohydrates is a cheap and efficient nanoscale energy storage system with high potential for practical applications and upscaling because of their natural abundance.
Materials & Design, 2021
This is a PDF file of an article that has undergone enhancements after acceptance, such as the ad... more This is a PDF file of an article that has undergone enhancements after acceptance, such as the addition of a cover page and metadata, and formatting for readability, but it is not yet the definitive version of record. This version will undergo additional copyediting, typesetting and review before it is published in its final form, but we are providing this version to give early visibility of the article. Please note that, during the production process, errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Clay Minerals, 2020
Tannic acid-stabilized silver nanoparticles were synthesized in situ on halloysite clay nanotubes... more Tannic acid-stabilized silver nanoparticles were synthesized in situ on halloysite clay nanotubes. The synthesis strategy included simple steps of tannic acid adsorption on clay nanotubes and further particle formation from silver salt solution. Pristine halloysite nanotubes as well as amino-modified clays were used for silver stabilization in water or ethanol. The materials were tested for antibacterial performance using three different methods. All of the materials produced showed antimicrobial activity. The pristine halloysite-based material with ~5 nm particles produced using ethanol as the solvent and tannic acid as the reducing agent showed the greatest antibacterial activity against Serratia marcescens. The materials were tested in vivo on Caenorhabditis elegans nematodes to ensure their safety, and they showed no negative effects on nematode growth and life expectancy.
ACS Omega, 2020
Studies of the physicochemical characteristics, group, and fractional composition of low-viscosit... more Studies of the physicochemical characteristics, group, and fractional composition of low-viscosity base oils with various nature were carried out. The influence of the composition of these oils on their low-and high-temperature characteristics was studied. Studies of the influence of the nature and composition of the dispersion medium on the physicochemical properties of low-temperature greases (LTG) thickened with lithium soap of stearic acid have been carried out. The possibility of expanding the operating temperature range and improving the antiwear properties of low-temperature greases through the combined use of low pour point mineral oil and high-index hydroprocessing oil has been found out. For the first time, the ability to predict the viscosity−temperature and tribological characteristics of lithium LTG based on standard methods for analyzing base oils are established.
ACS Sustainable Chemistry & Engineering, 2020
Equilibrium conditions of methane hydrate formation in the lumens of natural clay nanotubes were ... more Equilibrium conditions of methane hydrate formation in the lumens of natural clay nanotubes were analyzed. The water adsorbed by the pristine nanotubes is capable to form methane hydrate in the confined hydrophilic inner pores of 10 to 100 nm (surface chemistry of the inner lumens is Al 2 O 3 and external tube's surface is SiO 2). From 17.5 wt. % of water adsorbed by the clay, 12 wt. % were involved in the methane hydrate formation (conversion ~70 %). The crystal structure of the hydrate inside the nanoconfined spaces of halloysite did not change as compared with bulk systems. The formation of methane hydrate occurs during cooling at 0-6 °C simultaneously over the whole clay sample, indicating the catalytic activity of halloysite surface. This formulation slows down decomposition of the hydrate confined in the pores at atmospheric pressure at temperature below 0 °C. The water retained in the inner clay pores over the formation and decomposition of methane hydrate. We also modified halloysite nanotubes with mesoporous silica MCM-41(similar silica gel and sand are routinely used for gas hydrate formation) increasing the ratio of SiO 2 to Al 2 O 3 to compare methane hydrate formation in these chemically different pores. This allowed us to decrease substantially pore dimensions in the hybrid system (to 2-3 nm). The fraction of methane hydrate stable within the temperature range of-18 °C to 10 °C in this smaller pore hybrid system was 8 times less as compared to unmodified halloysite. The very small pores of halloysite/MCM-41 system allowed formation of hydrate only at a temperature significantly less than-18 °C. Natural halloysite clay nanotubes were suggested as efficient solid containers for methane hydrates encasing. Halloysite is cheap and scalable up to thousand tons; it is a mesomaterial capable of methane storage in clathrate hydrates with a water-based green chemistry processing. Suggested nanoclay based hydrate technology is also prospective for gas separation.
Catalysts, 2020
Mesoporous ruthenium catalysts (0.74–3.06 wt%) based on ordered Mobil Composition of Matter No. 4... more Mesoporous ruthenium catalysts (0.74–3.06 wt%) based on ordered Mobil Composition of Matter No. 41 (MCM-41) silica arrays on aluminosilicate halloysite nanotubes (HNTs), as well as HNT-based counterparts, were synthesized and tested in benzene hydrogenation. The structure of HNT core-shell silica composite-supported Ru catalysts were investigated by transmission electron microscopy (TEM), X-ray fluorescence (XRF) and temperature-programmed reduction (TPR-H2). The textural characteristics were specified by low-temperature nitrogen adsorption/desorption. The catalytic evaluation of Ru nanoparticles supported on both the pristine HNTs and MCM-41/HNT composite in benzene hydrogenation was carried out in a Parr multiple reactor system with batch stirred reactors (autoclaves) at 80 °C, a hydrogen pressure of 3.0 MPa and a hydrogen/benzene molar ratio of 3.3. Due to its hierarchical structure and high specific surface area, the MCM-41/HNT composite provided the uniform distribution and sta...
Molecules, 2020
The development of novel materials and approaches for effective energy consumption and the employ... more The development of novel materials and approaches for effective energy consumption and the employment of renewable energy sources is one of the current trends in modern material science. With this respect, the number of researches is focused on the effective harvesting and storage of solar energy for various applications. Phase change materials (PCMs) are known to be able to store thermal energy of the sunlight due to adsorption and release of latent heat through reversible phase transitions. Therefore, PCMs are promising as functional additives to construction materials and paints for advanced thermoregulation in building and industry. However, bare PCMs have limited practical applications. Organic PCMs like paraffins suffer from material leakage when undergoing in a liquid state while inorganic ones like salt hydrates lack long-term stability after multiple phase transitions. To avoid this, the loading of PCMs in porous matrices are intensively studied along with the thermal prope...
New Journal of Chemistry, 2020
We discuss prospects for halloysite nanotubes, vaterite crystals and nanocellulose to enter the m... more We discuss prospects for halloysite nanotubes, vaterite crystals and nanocellulose to enter the market of biomaterials for drug delivery and tissue engineering, and their potential for economically viable production from abundant natural sources.
Catalysts, 2019
Bimetallic catalysts (BMC) for hydroconversion of aromatic hydrocarbons (ArH) have been designed ... more Bimetallic catalysts (BMC) for hydroconversion of aromatic hydrocarbons (ArH) have been designed by modification of Ni/Al2O3 with chromium(0) compounds and phosphoromolybdic heteropolyacid (HPA). Catalysts were tested in hydrogenation of benzene and toluene, in hydrodemethylation of pure toluene and they were shown to possess a high activity, selectivity and sulfur tolerance under conditions of the processes above. The activity of BMC in these processes was much higher as compared with that of two-component (Ni-Cr, Ni-HPA) or conventional Ni/Al2O3 catalysts. Using BMC, hydrogenation of benzene and toluene proceeds with activity increased (up to 34–38 mol/kg·h) and toluene hydrodemethylation may be performed with improved selectivity (90.3%) and benzene yield (81%). The high sulfur tolerance of BMC was demonstrated by performing hydrodemethylation of toluene containing up to 500 ppm S.
Catalysis Today, 2019
Selective hydrogenation of terminal alkynes over palladium nanoparticles within the pores of amin... more Selective hydrogenation of terminal alkynes over palladium nanoparticles within the pores of amino-modified porous aromatic frameworks, Catalysis Today (2019),
Advanced Functional Materials, 2017
The alumosilicate materials of different morphologies such as platy and tubule nanoclays may serv... more The alumosilicate materials of different morphologies such as platy and tubule nanoclays may serve as an efficient protective encasing for the colored organic substances and nanoparticles. The adsorption of dyes onto the nanoclays increases their stability against the thermal, oxidative, and acid-base induced decomposition. Natural organic dyes form stable composites with nanoclays, thus allowing for "green" technology in production of industrial nanopigments. In the presence of high surface area alumosilicate materials, the semiconductor nanoparticles known as quantum dots are stabilized against agglomeration during their colloid synthesis resulting in safe colors. The highly dispersed nanoclays such as tubule halloysite can be employed as biocompatible carriers of quantum dots for the dual labeling of living human cells-both for dark-field and fluorescence imaging. Therefore, complexation of dyes with nanoclays allows for new stable and inexpensive color formulations.
Current Opinion in Colloid & Interface Science, 2018
Halloysite is natural tubular clay suitable as a component of biocompatible nanosystems with spec... more Halloysite is natural tubular clay suitable as a component of biocompatible nanosystems with specific functionalities. The selective modification of halloysite inner/outer surfaces can be achieved by exploiting supramolecular and covalent interactions resulting in controlled colloidal stability adjusted to the solvent polarity. The functionalized halloysite nanotubes can be employed as reinforcing filler for polymers as well as carriers for the sustained release of active molecules, such as antioxidants, flame-retardants, corrosion inhibitors, biocides and drugs. The tubular morphology makes halloysite a perspective template for core-shell metal supports for mesoporous catalysts. The catalysts can be incorporated with selective and unselective metal binding on the nanotubes' outer surface or in the inner lumens. Micropatterns of self-assembled nanotubes have been realized by the droplet casting method. The selective modification of halloysite has been exploited to increase the nanotubes' ordering in the produced patterns. Pickering emulsions, induced by the self-assembly of halloysite nanotubes on oil-water interface, can be used for petroleum spill bioremediation and catalysis.
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Papers by Vladimir Vinokurov