The carbonization temperature of carbon precursors before their activation is an important factor affecting the porous structure and properties of the resulting activated carbons. In this work сorrelation between the textural and adsorption properties of asphalt-based porous carbons and the carbonization temperature has been found. Additionally, the optimal carbonization temperature, and reasons why the carbonization temperature affects the main textural characteristics of the activated carbon were established. A series of porous carbons has been prepared from petroleum asphalt by a two-stage method, including carbonization of asphalt at different temperatures from 450 to 800 °C and KOH activation. To reveal the reasons of the correlation the carbonized samples were studied by TG-DTG, IR-Fourier, TEM methods. It is shown that the carbonization temperature effects on the structural defects, distance between the graphene layers, the reactivity and thermal stability of the carbonized asphalts. These specificities contribute to formation of porous structures of the activated carbons. The carbonization temperature 500–600 °С of the petroleum asphalt is found to be the optimal for further activation. The KOH activation of the petroleum asphalts carbonized at 500–600 °С provides microporous carbon with the high specific surface area (about 2000 m2g-1) and the CO2 uptake (3.3 mmolg-1). Additionally, the specific surface area of the activated carbons is shown can be predicted from the temperature of 50

The effect of thermal pretreatment on the porous structure and adsorption properties of asphalt-based carbons activated with potassium hydroxide was investigated by FTIR, Raman spectroscopy, TEM, N2 and CO2 adsorption. Two series of the activated carbons were prepared by a one-stage method using KOH as the activating agent and a two-stage method including pretreatment of asphalt at 450 °C. A cross-effect of the KOH/asphalt ratio and pretreatment conditions on the characteristics of the porous structure of the activated carbons was revealed. The pretreatment of asphalt before activation is demonstrated to be a necessary stage for the effective control of the carbon porous structure by variation the KOH/asphalt ratio from 2 to 4. The porous carbon derived from petroleum asphalt exhibited the high CO2 adsorption capacity of 3.8 mmol/g at 25 °C and 1 atm and good selectivity for CO2 over N2, indicating possible applications in CO2 capture technology.

In this article we report the investigation of a porous carbons prepared by free-template synthesis from polyfurfuryl alcohol (PFA) and template synthesis in the pores of amorphous silicas with different porous structures. The free-template synthesis of carbon from polyfurfuryl alcohol makes it possible to obtain ultramicroporous material with a low specific surface area and pore volume. The template synthesis in the pores of amorphous silicas using the carbon precursor PFA makes it possible to create amorphous carbon materials with a various porous structure repeating the texture specific of the template. Thus, microporous carbon and mesoporous carbon with an average pore size of 14 nm are formed when using micro- and mesoporous silicas, respectively. The pores less than 1 nm form for all carbon samples by the result of carbonization of PFA. The formation and size of these pores depend on both the nature and thermal history of a carbon precursor. Other pores of carbon samples are formed by the template.

This paper continues our previous study of porous amorphous silica prepared by the sol-gel method using polyethylene glycol (PEG) as structure-directing agent [O.V. Gorbunova et al., Microporous and Mesoporous Materials 190 (2014) 146-151]. Here we analyze the effect of acidic pH on the porous structure of silica synthesized with PEG. The results of adsorption studies and Si-29 NMR spectroscopy data allow us to declare the possibility of tuning the porous structure of the amorphous silica materials exploiting the PEG concentration and pH of the growth solution. Our results reveal that a gradual increase of the solution pH in the presence of PEG initiates the growth of specific surface area, specific mesopore volume and average pore size. We found that PEG makes it possible to obtain microporous silica materials in the pH region of stable sols (from 1 to 3). When pH is in the range from 4 to 5, micro-mesoporous materials with pore size less than 4 nm are formed.

The paper presents a technique for the synthesis of molybdenum carbide using mechanical activation of carbon black, which was impregnated with a 20% aqueous solution of ammonium heptamolybdate (AHM) using the incipient wetness technique, in an inert medium at a 100 g acceleration of milling bodies for 30 min. The mechanically activated carbide-containing composites were calcined in an inert medium at 800 degrees C. The composites were examined by a range of physical methods. It was shown that the mechanically activated composite consists of molybdenum carbide, iron oxide and iron carbide (about 4-8% according to AES-ICP). The phase addition method was used to determine the quantitative content of Mo2C, which was equal to 7.2 wt% in the calcined sample. Catalytic testing of mechanically activated molybdenum carbide in the partial oxidation of methane showed that the carbide-containing catalyst provides a 48-60% conversion of methane and an 83-85% selectivity for the target product (CO). (C) 2016 Elsevier B.V. All rights reserved.

Adamantane hydrocarbons have been isolated from Cenomanian heavy naphthenic oil of the Russkoe field using the thiocarbamide adduction method. Steam distillation of the oil has given a fraction (boiling range 105–150°C) containing 0.36 wt % adamantane, from which a concentrate containing 18.2 wt % C10–C14 adamantane derivatives has been obtained. Adamantane and its derivatives in the crude oil, oil fractions, and concentrate have been identified, and adamantane has been quantified using the gas chromatography—mass spectrometry technique.

A high-energy planetary mill AGO-2 was used for mechanical activation of synthetic graphite with the particle size of 25-30 mu m and specific surface area S-BET = 3.0 m(2)/g in air for 1-60 min at a 100 g acceleration of milling bodies. The X-ray diffraction, Raman spectroscopy and electron microscopy studies showed that the 60 min mechanical activation of graphite decreases the number of graphene layers in graphite crystallites to 8-12 and induces their turbostratic disorder. The size of graphite particles decreases to 6.9 mu m after 30 min of mechanical activation and increases to 12.1 mu m when the time of mechanical activation is extended to 60 min. Similar changes are observed for the true density of graphite: after 60 min of mechanical activation it becomes equal to 2.48 . 10(3) kg/m(3), which is by 10% higher than the true density of graphite not subjected to such treatment. The specific adsorption surface of graphite (S-BET) reaches its maximum values, 427-460 m(2)/g, after 7-12 min of mechanical activation. A further increase in the activation time to 30-60 min decreases S-BET of graphite to 230-250 m(2)/g.Due to attrition of steel milling bodies caused by mechanical activation, iron is accumulated in the samples and its content exceeds 5%. Iron is distributed uniformly in the graphite as the 30-100 and 3-5 nm particles of hematite and iron carbide. The IR spectroscopy study revealed the formation of 0.8 mEq/g of the hydroxyl, phenolic, lactone and carbonyl groups on the graphite surface in the course of mechanical activation. (C) 2015 Elsevier B.V. All rights reserved.

For changing the texture of the mesoporous carbon composite Sibunit, its modification by treatment with furfuryl alcohol and the solutions of furfuryl alcohol in water and benzene followed by the carbonization of a polymer was studied. It was found that the composition of a modifying liquid phase has an effect on the textural characteristics of Sibunit, and the most essential pore-size redistribution occurred with the use of the aqueous solutions of furfuryl alcohol. The conditions under which the micropore structure of the modified Sibunit was maximally developed were determined.

The paper presents that the graphite mechanical activation (MA) results in the particles size reduction and crystal structure disorder. The estimation of the electric conductivity of high-dispersive graphite powders was performed and the specific electric resistance improving is represented to occur after MA by two orders at the grinding bodies acceleration (1000 m/s2). Thus MA cannot be used for the particles size reduction, the electric resistance value being kept at the initial graphite level in the intensive conditions. The electric resistance of the samples improves from 2 to 6 times after MA at the low grinding bodies acceleration (300 m/s2) therefore MA in the “mild conditions” is more perspective approach to the conductive carbon powders development with the preset particles size.

С целью изменения текстуры мезопористого углеродного композита Сибунит проведены исследования его модификации путем обработки фурфуриловым спиртом и растворами фурфурилового спирта в воде и бензоле с последующей карбонизацией полимера. Показано, что на текстурные характеристики Сибунита оказывает влияние выбор состава модифицирующей жидкой фазы, и наиболее существенное перераспределение пор по размерам происходит при использовании водных растворов фурфурилового спирта. Определены условия, при которых происходит максимальное развитие микропористой структуры модифицируемого Сибунита.

Porous amorphous silica obtained by the sot-gel method with poly(ethylene glycol) (PEG) as structure directing agent is investigated. In this paper, we use the PEG with molecular weight 400, 1300, 3000, 6000, 20,000, 100,000, 200,000 and vary the concentration of the polymer solution in a wide range. The analysis of nitrogen adsorption-desorption data and transmission electron microscopy shows that depending on the combination of molecular weight and concentration of the PEG solution the microporous and mesoporous silica materials can be obtained. It was determined that using the solution of PEG-400, 1300 independently of the concentration the mesoporous silica is formed. When the diluted and concentrated solutions of PEG-3000, 6000, 20,000, 100,000, 200,000 are used it produces also the mesoporous materials. In the field of transitional concentrations of PEG the microporous silica with fraction of micropores equals 95% is generated. Revealed regularities are generalized and shown on the texture diagram. (C) 2014 Elsevier Inc. All rights reserved.

The effect of hydrothermal treatment temperature on porous structure of silica materials obtained with polyethylene glycol as structure-direct agent had been investigated. Characterization of the materials obtained by the method was carried out by nitrogen adsorption, Si-29 NMR, thermal analysis and SEM.It was shown that the conditions of the hydrothermal treatment in combination even with such a simple structure-direct agent as PEG significantly affect the porous structure of the material. Temperature of hydrothermal treatment plays an important role in the formation of the structure of silica materials and its variation allows us to produces both micro- and mesoporous silica materials. The resulting regularities can be used for targeted control of texture characteristics of silica materials.