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This work shows the inhibition property of the α-FeOOH nanoparticles on the oxidation reactions. The structure of the nanoparticles is confirmed by elemental analysis, FTIR, Mossbauer spectroscopy, TEM, and oxygen titration. We reveal that the α-FeOOH nanoparticles drastically inhibit the benzyl alcohol chain oxidation. The inhibition of the benzyl alcohol oxidation by the α-FeOOH nanoparticles is caused by the reactions between the nanoparticles and peroxyl radicals. Our finding suggests that the α-FeOOH nanoparticles may be used as an effective additive to preserve organic compounds from oxidation. Particularly, we illustrate that the α-FeOOH nanoparticles enhance the storage properties of motor fuel. The inhibition efficiency of the α-FeOOH nanoparticles may result in a variety of new applications of iron-containing nanoscale materials.

Background: Deposition of palladium nanoparticles from colloidal solution on various supports produces palladium catalysts with a predetermined size and concentration of the palladium nanoparticles, which allows to study the nanoparticle size effects and support influence on palladium catalytic properties. Objective: The goal of the present work was the development of a preparation method of systems supported on γ-Al2O3 palladium nanoparticles with a controlled size and determination of their thermal stability in oxidizing and reducing atmospheres. Methods: We demonstrated the preparation of Pd/γ-Al2O3 composite by precipitation of the size-controlled palladium nanoparticles with a narrow size distribution from colloidal solution. The composites were characterized by X-ray diffraction (XRD), and transmission electron microscope (TEM) methods. Result: The size and size distribution of the nanoparticles supported on γ-Al2O3 were found to be increasing upon precipitation due to strong Pd/γ-Al2O3 interaction. A significant enlargement of the supported nanoparticles occured at 300°C. The aggregation of the nanoparticles was observed at temperatures above 500°C resulting in an increase in their size. Conclusion: Our findings are not only applicable for the preparation of a model Pd supported on the γ-Al2O3 catalyst but could be applicable to the designing of the Pd-containing catalyst for important industrial high-temperature processes.

The catalytic properties of N-doped hydrazine-reduced graphene oxide (N-RGO) and thermally reduced graphene oxide (TRGO) in the hydrogenation of ethylene by molecular hydrogen were studied. Samples of the TRGO and N-RGO were characterized by transmission and scanning electron microscopy, X-ray diffraction, and Raman and X-ray photoelectron spectroscopy. It was shown that decrease of the oxygen content in the reduced graphene oxide increases its catalytic activity.

Nitrogen-doped reduced graphene oxide (N-RGO) was synthesized by the treatment of graphene oxide with hydrazine. The obtained material was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman , nitrogen adsorption-desorption isotherm, and XPS. The catalytic activity of N-RGO in acetylene, ethylene hydrogenation, and preferential acetylene hydrogenation in the ethylene excess was determined. In the acetylene hydrogenation, the selectivity of 97% for ethylene is achieved. A possibility of a complete conversion of acetylene to ethylene in the acetylene-ethylene mixture with ratio 1:9 is shown.

It was shown that a catalyst obtained by depositing palladium nanoparticles from a colloidal solution onto a carbon support stabilized with polyvinylpyrrolidone exhibits higher activity in liquid-phase hydrogenation of o-nitrotoluene than a commercial sample of Pd/C with the same palladium content. From analysis of data from TEM, XRD, and XPS it was concluded that the increase of activity is due to the increased content of Pd0 in the synthesized catalyst.

This work shows, for the first time, that the multi-walled carbon nanotubes (MWCNTs) exhibit the catalytic activity in the ethylene hydrogenation. MWCNTs with the average diameter of 35 nm were prepared by CVD from ethylene as a carbon source at 700 °C. TEM, SEM, and XRD indicate that MWCNTs are characterized by a sufficiently high defectiveness. FTIR highlights that the catalytic process occurs in the presence of the hydroxyl and carbonyl surface groups. We demonstrate the high catalytic stability of MWCNTs at temperatures up to 400 °C.

Catalytic activity was shown for N-doped reduced graphene oxide (N-RGO), subjected to prior thermal reduction in a hydrogen atmosphere, in the hydrogenation of ethylene and acetylene. Samples of N-RGO and activated N-RGO (N-RGO-H2) were characterized by SEM, TEM, IR spectroscopy, Raman spectroscopy, and X-ray diffraction (XRD). Our results indicate the catalytic activity of N-RGO-H2 may be attributed to the presence of nitrogen-containing fragments, which may reveal frustrated Lewis pairs properties.

It was shown that the structure of multilayer graphene oxide (GrO) synthesized by Tour method depends substantially on the degree of graphitization (g) and on the particle size of initial graphite. The obtained GrO was characterized by Raman and infrared spectroscopy, X-ray diffraction, and elemental analysis. The GrO contains carbonyl, carboxyl, and hydroxyl groups as well as C–O–C fragments. The dependence of the O/C molar ratio of GrO on the degree of graphitization of the parent graphite is nonmonotonic with a maximum at g ≈ 90%.

Nitrogen-doped reduced graphene oxide (N-RGO) was synthesized by the treatment of graphene oxide with hydrazine. The obtained material was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Raman spectoscopy, nitrogen adsorption-desorption isotherm, and XPS. The catalytic activity of N-RGO in acetylene, ethylene hydrogenation, and preferential acetylene hydrogenation in the ethylene excess was determined. In the acetylene hydrogenation, the selectivity of 97% for ethylene is achieved. A possibility of a complete conversion of acetylene to ethylene in the acetylene-ethylene mixture with ratio 1:9 is shown.

The hydrogenation of acetylene was investigated on multiwalled carbon nanotubes (MWCNTs) with an average diameter of 35 nm and prepared by chemical vapor deposition from ethylene. The MWCNT structure and surface-oxygen-containing functional groups were verified by transmission electron microscopy, scanning electron microscopy, X-ray photoelectron spectroscopy, Raman spectroscopy, and Boehm titration. Significant differences in the surface functionalities of the MWCNTs were found before and after catalysis, but the morphology of the MWCNTs did not change. During catalysis, the MWCNTs are characterized by a large number of defects and the surface is functionalized with hydroxy and carbonyl groups. The MWCNTs demonstrated high selectivity towards ethylene formation. The formation of methane was not recorded. Our study indicates that acetylene hydrogenation proceeds according to a Langmuir–Hinshelwood mechanism.

A summary is given of the results of studies of the catalytic properties of nanophase systems derived from copper, iron, and zirconium oxides in the ethanol steam reforming, the oxidation of carbon monoxide, the preferential oxidation of CO in the presence of excess hydrogen, the oxidation of benzyl alcohol, and the cracking of triglycerides. A relationship was found between the catalytic activity of copper, iron, and zirconium oxides and the size of their nanoparticles. The reasons for the nanophase effect in these processes were elucidated for a number of systems.

The production of supported on γ-A12O3 palladium catalysts by colloidal solution deposition method have been improved. Influence of temperature on the structure and dispersion characteristics of supported nanosized palladium particles during catalyst preparation and activation was investigated. It has been shown that at temperatures below 300oC monodisperse particles palladium catalysts are stable. Further temperature increase leads to aggregation of monodisperse metal nanoparticles by the mechanism of reaction-limited aggregation (RLA) to form polydisperse system.Key words: palladium nanoparticles, catalyst preparation, aggregation, catalyst thermal stability.

Nanoparticles of α-FeOOH with diameter 9.0 ± 0.8 nm catalyze the cracking of vegetable oil triglycerides to give motor fuel components in the temperature range 300-450 °C. The greatest amount of normal alkanes and least amount of oxygen-containing compounds are found in the liquid product mixture at 400 °C. The major products are components of the gasoline and diesel fractions.

Colloid deposition was used to prepare catalysts with controlled-size palladium nanoparticles supported on γ-Al2O3. The rate of ethylene hydrogenation was found to increase with increasing diameter of the palladium nanoparticles in the 4-6 nm range. The effective reaction activation energy was found to be independent of the size of the palladium nanoparticles. Thus, this nanodimensional effect may be a consequence of change in the ratio of the areas of the different crystallographic faces of palladium on the catalyst surface.

Multi-structuralized carbon nanotubes provide various possibilities to create a new generation of functional materials. In this article, the derivative surfaces of multi-wall carbon nanotubes (DSCNTs) have been developed by starting with initial carbon nanotubes (CNTs) to obtain the derivative structures of oxidized CNTs (oxCNTs) and unzipped CNTs (uCNTs). The Eu3+ complex is successfully directly anchored onto DSCNTs (Eu@DSCNTs) and produces linear fluorescence nanomaterials by introducing functional groups and sufficient specific surface area on the derivative surfaces. The obtained photophysical data, including UV absorption, fluorescence intensities and lifetimes, of the CNTs, oxCNTs and uCNTs have confirmed the improvement of derivative surfaces by oxCNTs and uCNTs, and the improvement is even greater for uCNTs. Furthermore, fluorescence fibres (Eu@DSCNTs/PAN) were obtained by electrospinning in a solution of Eu@DSCNTs with polyacrylonitrile (PAN). The fluorescence nanofibers have excellent fluorescence properties through the improvement of the derivative surface and exhibit excellent processability.

The possibility of producing nitrogen-containing multiwalled carbon macrotubes with an average external diameter of 220 nm was demonstrated for the first time. The macrotubes are characterized by bamboo-like morphology and are formed on aggregated particles of iron.

It was established that increase in the size of the iron nanoparticles in Fe/CNT nanocomposites from 4 to 8 nm leads to increase of their activity and selectivity with respect to methane in the hydrogenolysis of ethylene. The activity and selectivity of the nanocomposites are significantly higher than those of macrocrystalline iron, and this may be due to differences in the thermal conductivity of the bulk iron and the carbon nanotubes.

This is the first report of the inhibitory effect of iron(III) oxide-hydroxide nanoparticles on the liquid-phase radical-chain oxidation of benzyl alcohol by atmospheric oxygen. The dependence of the rate of oxidation of benzyl alcohol by atmospheric oxygen on the nanoparticle diameter in the range 1-30 nm is given by a curve with a maximum for nanoparticles with diameter ~9 nm. The inhibition of the oxidation of benzyl alcohol is attributed to an increase in the rate of chain termination reactions due to the reaction of the nanoparticles with peroxide radicals.

A graphene material was synthesized and investigated by atomic force microscopy, Raman spectroscopy, and X-ray diffraction analysis. It was shown that unlike activated carbon the obtained material exhibits catalytic activity in the hydrogenation of ethylene at temperatures in the range of 200-500 °C.

The catalytic properties of iron nanoparticles of size 4-8 nm, deposited on carbon nanotubes, in the hydrogenation of crotonaldehyde have been studied. It has been shown that the activity of the catalysts depends in an irregular manner on their dimensions and covers the range (1.6-5.0)∙10-6 mol∙m-2∙s-1. It has been established that the dependence of the selectivity of the hydrogenation products on the size of the supported nanoparticles has an extreme for 6.8 nm nanoparticles.

Core-shell nanoparticles Fe@Fe3O4 supported on activated carbon (AC) and carbon nanotubes (CNTs) have been studied by H2 temperature-programmed reduction (TPR). Nanoparticles with size of 6.5 nm were synthesized by iron(II) oleate thermal decomposition and were supported on activated carbon and carbon nanotubes by colloid deposition method. The nanoparticles Fe@Fe3O4 are characterized by TEM and IR. Reduction of nanoparticles on AC starts at 140?C, whereas reduction of nanoparticles on CNTs starts at 200?C. Moreover, gasification of CNTs with methane releasing starts at 450?C, whereas gasification of AC is negligible at temperatures up to 800?C. All these findings illustrate a strong difference in the interaction between nanoparticles and the support material for AC and CNTs.

Fe@Fe3O4 nanoparticles of controlled size, deposited on carbon nanotubes, were obtained by deposition from colloidal solutions. It was shown that the size and size distribution of the nanoparticles do not change during deposition on carbon nanotubes. By temperature-programmed reduction with hydrogen it was established that the temperatures at the beginning of reduction of the Fe@Fe3O4/CNT samples do not depend monotonically on the size of the deposited nanoparticles.