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, N
2
...and CO
2
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 CO
2
adsorption capacity of 3.8 mmol/g at 25 °C and 1 atm and good selectivity for CO
2
over N
2
, indicating possible applications in CO
2
capture technology.
Graphical abstract
Porous carbon–carbon composite materials (PCCCM) were synthesized by the alkaline dehydrochlorination of polyvinyl chloride solutions in dimethyl sulfoxide containing the modifying additives of a ...nanostructured component (NC): graphite oxide (GO), reduced graphite oxide (RGO) or nanoglobular carbon (NGC), with subsequent two-step thermal treatment of the obtained polyvinylene–NC composites (carbonization at 400 °C and carbon dioxide activation at 900 °C). The focus of the study was on the analysis and digital processing of transmission electron microscopy images to study local areas of carbon composite materials, as well as to determine the distances between graphene layers. TEM and low-temperature nitrogen adsorption studies revealed that the structure of the synthesized PCCCM can be considered as a porous carbon matrix in which either carbon nanoglobules (in the case of NGC) or carbon particles with the “crumpled sheet” morphology (in the case of GO or RGO used as the modifying additives) are distributed. Depending on the features of the introduced 5–7 wt.% nanostructured component, the fraction of mesopores was shown to vary from 11% to 46%, and SBET—from 791 to 1115 m2 g−1. The synthesis of PCCNC using graphite oxide and reduced graphite oxide as the modifying additives can be considered as a method for synthesizing a porous carbon material with the hierarchical structure containing both the micro- and meso/macropores. Such materials are widely applied and can serve as adsorbents, catalyst supports, elements of power storage systems, etc.
Changes in the structural and textural properties of NiAl-layered double hydroxides (LDHs) (with 2–4 molar ratios of metals) and state of nickel that occur in different steps of the synthesis of ...nickel catalysts were studied using XRD, thermal analysis, TPR, low-temperature nitrogen adsorption, XANES, EXAFS, and electron microscopy methods. Relations between nickel content, catalyst reduction conditions, state of nickel, and its catalytic properties were revealed. It was shown that the use of NiAl LDH as the catalyst precursor even at a high content of active metal allows for the obtaining of the dispersed particles of supported nickel that are active in the aqueous-phase hydrogenation of furfural. The catalyst activity and conversion of furfural were found to increase with elevation of the catalyst reduction temperature and the corresponding growth of the fraction of reduced nickel. However, a lower reduction temperature (500 °C) makes it possible to form smaller nickel particles with the size of 4–6 nm, and a high Ni content (Ni:Al = 4) can be used to obtain the active Ni@NiAlOx catalyst. Under mild reaction conditions (90 °C, 2.0 MPa), the furfural conversion reached 93%, and furfuryl alcohol was formed with the selectivity of 70%. Under more severe reaction conditions (150 °C, 3.0 MPa), complete conversion of furfural was achieved, and cyclopentanol and tetrahydrofurfuryl alcohol were the main hydrogenation products.
The palladium catalysts prepared using carbon nanoglobules (CNGs) as the support and containing no more than 2 wt% Pd were shown to be highly effective for the liquid-phase hydrogenation of ethyl ...4-nitrobenzoate under mild conditions. Regardless of the kind of CNGs and the catalyst preparation method, the most of the Pd/CNGs catalysts allow achieving a complete conversion of substrate giving benzocaine in a 100% yield. The Pd/CNGs catalyst is easily recycled many times without loss of its catalytic performance. The results obtained may be useful for the development of effective Pd/C catalysts for chemoselective hydrogenation of various nitroarenes.
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•Pd/CNGs is a promising catalyst for hydrogenation of ethyl 4-nitrobenzoate.•Pd/CNGs allow obtaining benzocaine in a 100% yield.•CNGs kind affects the reducibility and dispersion state of supported Pd.•Pd/CNGs can be a practical catalyst for synthesis of benzocaine and other anilines.
Ni(Mg)Al-layered double hydroxides (LDH) were synthesized by coprecipitation. Structural properties of LDH and mixed oxides Ni(Mg)AlOx, obtained by LDH calcination, were studied by XRD and SEM. ...Textural properties of Ni(Mg)AlOx were studied by the nitrogen adsorption-desorption method. It was found that the formation of the single-phase LDH was occurred for any nickel content in the samples. The mixed oxides have a high specific surface area, the value of which decreases with increasing nickel content in the samples. Ni(Mg)AlOx are characterized by high activity in furfural hydrogenation. Selectivity of the formation of different reaction products depends on the nickel content in the catalysts. The full furfural conversion with the furfuryl alcohol selectivity no more than 65% was observed for the catalyst with a low nickel content. At the same time an increase in selectivity for furfuryl alcohol up to 84% occurs for the NiAl-catalyst with a furfural conversion not exceeding 43%.
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•Synthesis of single-phase Ni(Mg)Al-layered hydroxides by coprecipitation.•Structural and textural properties of the Ni(Mg)Al-layered hydroxides and their calcined forms.•High activity of the Ni(Mg)AlOx catalysts in the reaction of aqua-phase furfural hydrogenation.•Selectivity of products formation can vary by changing the nickel amount in the Ni(Mg)AlOx catalysts.
The effect of the support nature (different carbons, aluminum oxide, mixed MgAl oxide) on the activity of palladium catalysts and on the reaction routes of aqueous-phase hydrogenation of furfural at ...a temperature of 423 K and a pressure of 3 MPa was investigated. The carbon-supported catalysts were found to be the most active, and almost complete conversion of furfural is achieved. In the presence of these catalysts, the reaction proceeds predominantly through two parallel water-involved routes depending on the nature of carbon support: catalysts supported on carbon nanoglobules are selective to 4-oxopentanal (selectivity up to about 63%), while catalysts supported on carbon nanotubes give mainly cyclopentanone (selectivity up to 57%). The palladium catalysts based on the oxide supports (γ-Al
2
O
3
, MgAlO
x
) are much less active in the aqueous-phase hydrogenation of furfural compared to carbon-supported catalysts, and complete conversion of furfural does not occur (only up to 55%). In the presence of catalysts prepared using basic support (i.e., MgAl oxide), there are no reactions involving water, and furfuryl alcohol and tetrahydrofurfuryl alcohol are the principal products. According to the results of catalyst characterizations, the revealed differences in performance of palladium catalysts are caused by the effect of the support nature on the formation and dispersion of supported Pd nanoparticles, as well as by the distinctions in the structure and acid–base properties of the supports.
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•In doping at the AlOOH peptization increases SBET and decreases CSR size of Al2O3.•Alumina doped with 0.3 wt.% In from In(OH)3 reveals the indium oxide phase.•In interacts with Pt in ...Pt/Al2O3In system with formation of Pt-In alloys.•In is a good modifier to decrease aromatics, increase isomers.•The highest isomers selectivity is observed for Pt/Al2O3In with using In(OH)3.
Monometallic indium-doped Pt/Al2O3catalysts for n-heptane reforming were studied using the low-temperature adsorption of nitrogen, XRD, NH3-TPD, and H2-TPR. The introduction of indium at the step of aluminum hydroxide peptization increases SBET of the produced alumina and decreases its size of coherent scattering region (CSR). The H2-TPR data testify to a strong Pt-In interaction, probably leading to the formation of Pt-In alloys. The NH3-TPD results demonstrate the addition of indium to alumina decreases the fraction of strong and medium acid sites. In n-heptane reforming, the presence of indium enhances the catalyst selectivity for isomers and decreases the selectivity for hydrogenolysis and aromatization products. Such effects are most pronounced for the Pt/Al2O3InH-Cl sample with indium hydroxide used as the precursor.
Catalysts based on CuAl-, CoAl-, and CuCoAl-layered hydroxides with M2+/Al = 2 and Cu/Co = 1 molar ratio were obtained. The effect of amount of cobalt on the structural properties, morphology, ...surface cations distribution, oxide phase formation, thermal stability of the samples and reduction of metals from them was studied. The effect of reaction conditions (temperature, time, pressure, solvent) and conditions of preliminary treatment of catalysts on their catalytic properties in furfural hydrogenation was established. High selectivity to furfuryl alcohol was observed for all the samples irrespective of pretreatment and reaction conditions. The synergetic effect in furfural hydrogenation between Co and Cu in the CuCoAlOx catalysts was revealed when ethanol is used as a solvent.
The hypothesis of study: there are statistically significant differences in the motivational and volitional sphere of transport police officers in command and civilian positions. This is due to the ...specifics of the professional activities of employees of command positions: the importance of goals, high requirements for stress resistance, personal reliability, discipline, endurance. This requires high motivation and strongwilled endurance. The study involved 44 employees of the East-Siberian Linear department of the Ministry of Internal Affairs of the Russian Federation on transport aged 26 to 42 years, all men. Of these, 22 are employees who hold command positions, 22 are employees who hold civilian positions. The results of the study confirm the hypothesis. The motivational and volitional sphere of employees of command and civilian positions of the transport police has statistically significant differences: for citizens, comfort and good conditions are important for a sense of well-being at work. Whereas employees of command positions prefer to realize in the profession through the opportunity to be useful to people and help them.
