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Carbon nanofibers (CNFs) have been rapidly synthesized on the surface of low-cost commercial chlorinated polymers (chlorinated polyvinyl chloride, polyvinyl chloride), which contains iron compounds, under the action of a high power ion beam at room temperature. Organic (Fe(C 5 H 5 ) 2 ) and inorganic (FeCl 3 ⋅6H 2 O и Fe(NO 3 ) 3 ·9H 2 O) iron compounds were used as catalytic additions. SEM, TEM and Raman spectroscopy were used to investigate the morphologies and structure of irradiated polymers. CNFs had a most probable diameter in the range 50–90 nm and a maximum length of up to 10 μm. The maximum CNFs growth rate was estimated as 160 μm/μs. A possible growth mechanism for CNFs is discussed. [ABSTRACT FROM AUTHOR]

[Display omitted] • Hydrogen-assisted CCVD of ethylene over a bulk Ni-Cu alloy was studied. • The highest carbon yield was achieved in the hydrogen content range of 40–70 vol% • As found, the hydrogen supply is required throughout the process. • The presence of hydrogen prevents deactivation of the catalytic particles. • Both the structural and textural characteristics of CNFs are affected by hydrogen. Carbon nanofibers with specified textural characteristics, obtained via catalytic chemical vapor deposition of various hydrocarbons, attract growing interest from both scientists and industrialists. In the present work, the optimal hydrogen content in terms of the carbon accumulation rate, process selectivity, and productivity of the Ni-Cu catalyst was found to be in the range of 40–70 vol%. As was revealed by the X-ray diffraction analysis, the catalytic particles are represented by a solid Ni-Cu solution based on the fcc lattice of Ni, and their composition does not depend on the hydrogen concentration. As found, the introduction of an optimal hydrogen amount into the initial reaction mixture decreases A D /A G (from 2.59 to 2.43) and increases both specific surface area (from 127 to 165 m2/g) and total pore volume (from 0.15 to 0.26 cm3/g). Thus, the effect of hydrogen on the decomposition of ethylene over self-dispersing catalysts is studied for the first time. [ABSTRACT FROM AUTHOR]

The resistance of the Pd/C samples towards hydrogenation of the carbon support was studied in the temperature-programmed and isothermal regimes. Carbonaceous graphite-like material Sibunit was used as a carbon support. Pristine Sibunit was additionally graphitized via high temperature treatment (1900 °C) in an inert atmosphere. Both initial and graphitized supports were subjected to oxidative treatment in order to increase the amount of surface functional oxygen-containing groups. Palladium (1 wt%) was supported using an aqueous solution of H 2 PdCl 4 . All the samples were characterized by a low-temperature adsorption of nitrogen, transmission electron microscopy, and Raman spectroscopy. The graphitization procedure was found to decrease significantly the specific surface area of the support, while the oxidative treatment affects this parameter negligibly. Testing the Pd-containing samples in a hydrogen flow revealed the following order in accordance with amount of methane released: Pd/iSib » Pd/iSib-ox > Pd/gSib > Pd/gSib-ox. [ABSTRACT FROM AUTHOR]

The present work is devoted to the study of doping effects of zinc, gallium and silver on the structure of active sites and catalytic properties of carbon-supported 0.5 wt% Pd catalysts in the liquid-phase selective hydrogenation of acetylene to ethylene. Carbonaceous graphite-like material Sibunit was used as a support. The reaction was performed in a medium of N -methyl-2-pyrrolidone at 55 °C. It was shown that the bimetallic Pd-Zn/C, Pd-Ga/C and Pd-Ag/C catalysts exhibit better activity and selectivity towards target product if compare with the monometallic Pd/C catalyst. The ethylene yield increases in a row as follows: Pd/C (19%) < Pd-Ag/C (34%) < Pd-Ga/C (42%) < Pd-Zn/C (53%). Using X-ray absorption spectroscopy and transmission electron microscopy it was found that an improvement of the selectivity is stipulated by the formation of bimetallic PdZn, Pd x Ga y and PdAg nanophases. In the case of Pd-Zn/C and Pd-Ag/C systems, an increased distance between neighboring Pd atoms (2.82–2.89 Å) in relation with monometallic Pd/C, where this distance is 2.72 Å, was observed. The higher activity of modified bimetallic systems is connected with increased number of active sites due to enhanced dispersity of supported palladium doped with second metal. [ABSTRACT FROM AUTHOR]

Highlights: [•] Mo doped carbon aerogels are active catalysts in hydroconversion of acetic acid. [•] The mechanism of the hydrogenation depends on Mo concentration. [•] Post-catalysis analysis reveals severe changes in morphology and chemistry. [•] Highest selectivity for ethanol is 16% when 85% of the acetic acid is converted. [Copyright &y& Elsevier]

The formation of a layer of porous carbon on the surface of low-cost commercial chlorinated polyvinyl chloride (CPVC) with the addition of ferrocene under the action of an intense electron beam of microsecond duration was investigated. The polymer was irradiated using a pulsed fore-vacuum plasma source of a large-diameter electron beam (cross-sectional area ∼100 cm2), which allows minimizes polymer charging during irradiation. The methods of scanning and transmission electron microscopy, EDX spectroscopy, Raman and X-ray photoelectron spectroscopy were used to study the carbon layers. We found that the carbon layer consists mainly of thin (∼10 nm) sheets of amorphous carbon containing curved graphene layers up to 4 nm in length. According to the XPS data analysis, the relative fraction of graphitized carbon (sp2-hybridized carbon) reaches 80% in the surface layer with a thickness of up to 3 nm. Possible mechanisms for the formation of a porous carbon layer on the CPVC surface were discussed. The porous carbon layer has a specific capacitance of 14 mF/cm2 at a scan rate of 5 mV/s. In many applications, it can be an alternative to the laser-induced graphene formed on the surface of expensive high-temperature polyimide. [Display omitted] • The surface layer of CPVC film containing ferrocene is transformed into porous carbon by pulsed electron beam irradiation. • The carbon layer consists mainly of nanosheets with a cross-sectional size of ∼5 μm and a thickness of ∼10 nm. • Two types of organization of graphene layers were observed in these nanosheets. • The resulting carbon layer has a specific capacitance of up to 14 mF/cm2 and can be used to manufacture supercapacitors. [ABSTRACT FROM AUTHOR]

• Pd-Ag/Sibunit catalysts are promising in C 2 H 4 production by acetylene hydrogenation. • ~ Pd 0.6 Ag 0.4 particles are formed during treatment in H 2 at t = 400–500 °C. • The Pd-Pd distance in the ~ Pd 0.6 Ag 0.4 particles is 2.78–2.80 Å. • The sample treated in H 2 at t = 400 °C have an average particle size of 2.9 nm. • The ethylene selectivity of the Pd-Ag/Sibunit treated with H 2 at 400–500 °C is 77–78%. The formation process of the active component of 0.5%Pd-0.5%Ag catalysts supported on the carbon black/pyrolytic synthetic carbon composite «Sibunit», which were synthesized by joint impregnation, was studied. XRD and EXAFS studies revealed that heating of the Pd-Ag/Sibunit catalyst in hydrogen at 400–500 °C results in the formation of bimetallic solid solution Pd 0.6 Ag 0.4. The bimetallic particles are characterized by an increased distance between neighboring palladium atoms (2.78–2.80 Å), as compared to metallic palladium and by an increase in the electron density on palladium atoms under the action of silver (according to XPS data). The synthesized samples with supported Pd-Ag nanoparticles make it possible to obtain С 2 Н 4 by ethyne hydrogenation with the selectivity of 77–78%. [Display omitted] [ABSTRACT FROM AUTHOR]