A new way of synthesizing metal–carbon nanocomposites via simultaneous pyrolysis and the chemical activation of a precursor based on polyacrylonitrile and cobalt carbonate under IR radiation is proposed. Structural characteristics of samples synthesized both without alkali and in the activation process are compared. The effect the metal has on the structure of the carbon and the size of its specific surface area is shown. The specific surface area of the sample synthesized with the simultaneous formation of the carbon matrix, its activation, and the reduction of the metal is 1232 m2/g. Cobalt nanoparticles are found to have cubic face-centered and hexagonal close-packed lattices.

Ethanol steam reforming (ESR) over a Pt–Ru(0.3%) catalyst supported on detonation nanodiamonds (DNDs) and on DNDs containing no noble metals has been studied. It has been shown that the two catalysts provide the formation of the same products; however, their yield and distribution significantly change after supporting Pt–Ru on DND. The adsorbed species that formed during ESR over DND and the Pt–Ru(2.5%)/DND model catalyst have been studied by in situ high-temperature diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). It has been shown that the ability of pure DND to mediate the ESR process is provided by the carbonyl and carboxyl groups on the DND surface; this feature is the main difference of the Pt–Ru/DND catalytic nanocomposite from catalysts in which Pt and Ru are supported on various oxides. On the basis of a comparison of the results obtained during ESR in a catalytic reactor and in a DRIFTS cell, a mechanism of the process over DND-supported catalysts has been proposed.

The physicochemical and catalytic properties of pyrolyzed cellulose-based Cu–Co solid dispersed composite catalysts synthesized by matrix isolation under the action of IR radiation have been studied. It has been shown that alcohols can be produced from CO and H 2 in the presence of the synthesized composite catalysts comprising Cu–Co solid dispersed phase nanoparticles. The effect of synthesis conditions on the structure of the composite catalysts and their activity in synthesis gas conversion to alcohols has been studied by X-ray diffraction analysis, ATR-FTIR spectroscopy, and in situ magnetometry.

Nanocomposite materials based on poly(vinyl alcohol), cellulose, polystyrene, and styrene–divinylbenzene copolymer are synthesized by IR pyrolysis, and their structures are studied by FTIR spectroscopy and X-ray powder diffraction. It is found that the composites show catalytic activity in Fischer–Tropsch synthesis. An explanation is provided for the high catalytic activity of the test systems.

Обнаружено, что синтезированный композиционный материал на основе железосодержащих полимерных микросфер проявляет высокую каталитическую активность в синтезе Фишера–Тропша. Методом ИК-Фурье-спектроскопии изучено строение исходного формованного сополимера и синтезированного нанокомпозита. Магнитные свойства материала изучены магнитометрическим методом in situ.

The influence of polymer matrix on the activity of composite material containing cobalt nanoparticles in Fischer-Tropsch synthesis was studied. It was found that the structure of the polymer matrix affects active centers formation. Magnetometry techniques in situ and XRD confirmed the presence of the metal cobalt and its oxide phases which are the active centers of different type effect.

It has been found that the composite material synthesized on the basis of iron-containing polymer microspheres exhibits high catalytic activity in the Fischer-Tropsch process. The structure of the original molded copolymer and the synthesized nanocomposite has been studied by FTIR spectroscopy. The magnetic properties of the material have been examined by in situ magnetometry.

The Fischer-Tropsch synthesis in the presence of composite materials prepared by the IR pyrolysis of polyacrylonitrile (PAN) with cobalt salts immobilized on it was studied. The catalysts were small granules containing PAN carbonization products and to 80% cobalt metal particles of size 10–17 nm. The synthesis was performed in flow reactors with a fixed bed and a catalyst bed suspended in a liquid at 2–3 MPa and 200–310°C. It was established that the activity of the catalyst depends on the nature of the cobalt salt used, the temperature of IR pyrolysis, and the synthesis conditions. The catalyst prepared with the use of cobalt carbonate exhibited the greatest activity. The yield of liquid hydrocarbons on it reached ∼70 g/m 3 at ∼60% selectivity. It was found that the test composite materials were characterized by an extremely high productivity of 2–5 kg (kg Co) −1 h −1 .

In this paper we report the results obtained by the comparative study of catalytic activity of monometallic (Ni, Cu, Ru, Pt) and bimetallic (Pt-Ni, Pt-Cu, Pt-Ru) catalysts synthesized on a surface of detonation nanodiamond (DND) supports in steam reforming of methanol and ethanol for hydrogen production. All obtained catalysts (M/DND) were characterized by TEM, FTIR spectroscopy, X-ray diffraction. The specific surface area of DND-nanocomposites was also evaluated by using BET technique. The obtained WDND catalysts demonstrated high activity in methanol and ethanol steam reforming reactions. It has been shown that the most active monometallic catalyst is ruthenium one, while Pt-Ru catalyst demonstrates the highest activity in comparison with other bimetallic samples. Copyright (C) 2014, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.

Изучено протекание синтеза Фишера–Тропша в присутствии композиционных материалов, приготовленных ИК-пиролизом полиакрилонитрила (ПАН) с иммобилизованными на нем солями кобальта. Катализаторы представляли собой мелкие гранулы, содержащие продукты карбонизации ПАН и до 80% частиц металлического кобальта размером 10–17 нм. Синтез осуществляли в проточных реакторах с фиксированным и суспендированным в жидкости слоем катализатора при 2–3 МПа и 200–310°C. Установлено, что активность катализатора определяется природой лиганда использованной соли кобальта, температурой ИК-пиролиза и условиями проведения синтеза. Наибольшей активностью обладал катализатор, приготовленный с использованием карбоната кобальта. Выход жидких углеводородов на нем достигал 70 г/м3 при селективности 60. Показано, что изученные композиционные материалы отличаются исключительно высокой производительностью, которая достигает 2–5 кг/кгСо · ч.

Physicochemical properties and catalytic performance of detonation nanodiamonds were studied. Original samples of nanodiamonds and nanodiamonds modified by hydrogen, oxygen, and nitric acid with hydrogen peroxide and infrared-treated were investigated. The catalyst structure and morphology were examined by transmission electron microscopy and IR spectroscopy. All the investigated catalysts were active in the steam reforming of ethanol. The correlation of catalytic properties with composition and structure of the described systems is discussed. The specific surface area of nanodiamonds is changed insignificantly upon modification.

The structure of nanocomposites of the C-Pd system has been studied by X-ray diffraction analysis and transmission electron microscopy. Variations in the lattice period of nanosized palladium, the average amount of hydrogen dissolved in it, and the size distribution of palladium nanoparticles have been analyzed as functions of the nanocomposite fabrication temperature. Based on the structural data, the solubility of hydrogen in nanosized palladium has been estimated.

Методами рентгенофазового анализа и просвечивающей электронной микроскопии изучена структура нанокомпозитов системы C–Pd. В зависимости от температуры приготовления нанокомпозитов установлено изменение периода решетки наноразмерного палладия и среднее количество растворенного в нем водорода, а также распределение наночастиц палладия по размерам. На основании структурных данных оценена растворимость водорода в наноразмерном палладии.

Metal-carbon nanocomposites comprising carbon matrices of a graphite-like structure with dispersed CuZn2 and CuZn5 bimetal nanoparticles have been obtained for the first time under conditions of the IR pyrolysis of the precursor based on polyacrylonitrile and copper and zinc acetates (Zn : Cu ratio = 1 : 5). It has been demonstrated that the CuZn5 phase formation starts at 300°C, whereas the CuZn2 phase formation starts at T > 500°C. The CuZn2 and CuZn5 bimetal nanoparticles coexist in the structure of nanocom-posites obtained at T ≥ 700°C. Here the CuZn2 bimetal nanoparticle fraction increases with an increase in the intensity of the IR pyrolysis.

Metal-carbon nanocomposites consisting of a carbon matrix with dispersed nanosize bimetallic Pd-Fe particles were obtained. It was established that at 500–700°C, the bimetallic particles form a solid solution of iron in palladium. It was concluded that raising the intensity of infrared pyrolysis to 800–1100°C leads to the formation of intermetallic compounds whose composition depends on the temperature of nano-composite fabrication.

The nanostructured catalytic membranes consisted of stainless steel porous support modified with carbon layer, and catalytic layer, containing Pt–Ru alloy nanoparticles, homogeneously dispersed in carbon matrix, were synthesized for the first time by IR-pyrolysis method. The optimization of pore size of plates of porous stainless steel was carried out using carbon, prepared by IR-pyrolysis of PAN, introduced in support pores in DMFA solution. The structure and thickness of modifying layer were controlled by PAN initial concentration and IR-annealing intensity. The selectivity of helium–argon pair separation increased monotonously as carbon layer thickness increased. The catalytic layers, based on IR-PAN carbon, Pt–Ru nanoparticles and finely dispersed activated carbon SKT or detonation nanodiamonds, were deposited on carbon modified porous membranes. The selectivity of permeability for pair helium–argon increased after catalytic layer deposition, becoming equal to the ideal Knudsen value. Cyclohexane dehydrogenation on obtained composite metal–carbon membrane catalysts were carried out in plug flow catalytic membrane reactor at the temperatures from 220 to 520°C. The productivity on the unit of mass of active metal of composite membrane metal–carbon catalyst, was shown to be significantly higher than that of the same metal–carbon composites in grained form.