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11.
B. B. Troitskii A. A. Lokteva V. N. Denisova M. A. Novikova A. N. Konev I. L. Fedyushkin 《Russian Journal of Applied Chemistry》2016,89(7):1132-1136
The mean size of the latex particles formed in emulsion polymerization of methyl methacrylate under definite conditions (water: monomer volume ratio 15: 1, 80°C, potassium persulfate concentration 0.07 wt %) decreases from 200 to 9–10 nm as the concentration of an ionic surfactant (anionic Disponil AES 60, SDS, cationic C19H42BrN) is increased from 0.0 to 1.0 wt %. The nonionic surfactants studied influence the size of the latex particles formed differently: with ALM-10, the particle size decreases from 200 to 150–190 nm, whereas with ALM-7 and ALM-2 it increases from 200 to 320 nm as the surfactant concentration is increased from 0.0 to 1.0 wt %. An increase in the concentration of F127 amphiphilic ternary block copolymer from 0.0 to 1.0 wt % leads to a monotonic decrease in the size of the poly(methyl methacrylate) latex particles formed from 200 to 53 nm. 相似文献
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M. D. Navalikhina N. E. Kavalerskaya E. S. Lokteva A. A. Peristyi E. V. Golubina V. V. Lunin 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2012,86(12):1800-1807
It is established that unmodified Ni catalysts and Ni catalysts modified with Mo- and W-heteropoly compounds (HPC) of the Keggin type (6 wt %) along with catalyst containing 6% K4SiW12O40/Al2O3 appear to be active in the reaction of phenylacetylene (PA) hydrogenation. At low temperatures (100?C150°C), the selectivity of the process strongly depends on the nature of the modifier or second active metal (Pd). It is demonstrated that in the presence of 6% Ni-0.015% Pd/Al2O3 modified by HPC K4SiMo6W6O40, the conversion of PA at 100°C was 87% at a styrene: ethylbenzene ratio of 1: 1. The acidity of HPC is found to influence the side reactions of alkylation and condensation. Transmission electron microscopy demonstrates that Ni in modified HPC 6% Ni/Al2O3 is present in the form of the particles below 2 nm in size, and these particles of Ni become larger when affected by the reaction medium during PA hydrogenation. 相似文献
13.
S. A. Kachevskii E. V. Golubina E. S. Lokteva V. V. Lunin 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2007,81(6):866-873
Ultradisperse diamond was studied as a promising carrier for Pd-containing hydrodechlorination catalysts. Transmission electron microscopy, temperature-programmed reduction, and the adsorption method were used to study catalysts on ultradisperse diamond and activated carbon and a commercial catalyst from Fluca. Catalyst activities in multiphase hydrodechlorination of chlorobenzenes were compared. The activity of Pd-containing catalysts on ultradisperse diamond was found to be several orders of magnitude higher than that of Pd catalysts on activated carbon. 相似文献
14.
E. S. Lokteva V. I. Simagina E. V. Golubina I. V. Stoyanova V. V. Lunin 《Kinetics and Catalysis》2000,41(6):776-781
Along with hydrodechlorination, the formation of C1 and higher hydrocarbons takes place in a flow system in the presence of catalysts containing 0.5–5.0% Pd supported on a Sibunit carbon carrier at 150–230°C. In the entire range of conditions examined, the reaction products are primarily methane, C2–C4 hydrocarbon fractions, and C5 traces. The catalysts are stable in operation, and a high conversion of CCl4 was retained for a long time interval. The nonselective formation of linear and branched hydrocarbons is indicative of a radical mechanism of the process. 相似文献
15.
A. V. Erokhin E. S. Lokteva E. V. Golubina K. I. Maslakov A. Ye. Yermakov M. A. Uimin V. V. Lunin 《Russian Journal of Physical Chemistry A, Focus on Chemistry》2014,88(1):12-16
Nickel-containing metal-carbon nanocomposites (Ni@C) synthesized by levitation melting in a flow of an inert gas-hydrocarbon mixture were used as catalysts of the hydrogenation of phenylacetylene (PA). The nanocomposites were characterized by X-ray photoelectron spectroscopy, simultaneous thermal analysis, and temperature-programmed reduction. The nickel-carbon nanocomposites were stable on storage in air, with only 13% of the total amount of nickel oxidized after 3.5 years of storage. In addition to nanoparticles completely covered with carbon, the composites contained partially coated metal particles, which are readily oxidized in air. Both types of particles exhibited the catalytic activity in phenylacetylene hydrogenation. At higher contents of nickel partially coated with carbon, the activity increased and the selectivity of styrene formation decreased. The minimum half-conversion temperature (75°C) was determined for a specially prepared Ni@C sample with an increased content of oxidized nickel (28%). The maximum selectivity of styrene formation (~75% at 150°C) was recorded in the presence of the sample with the smallest amount of oxidized nickel (less than 4%). 相似文献
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17.
Troitskii B. B. Lokteva A. A. Novikova M. A. Lopatina T. I. Fedyushkin I. L. 《Russian Journal of Applied Chemistry》2020,93(2):232-237
Russian Journal of Applied Chemistry - The effect of the hexadecyltrimethylammonium bromide concentration in the silica sol, which is used to obtain antireflection coatings over silicate glass, on... 相似文献
18.
Dr. Lara Frenzel Dr. Irina Lokteva Michael Koof Dr. Suresh Narayanan Prof. Dr. Gerhard Grübel Dr. Felix Lehmkühler 《Chemphyschem》2020,21(12):1318-1325
We study the structure and dynamics of poly(N-isopropylacrylamide) (PNIPAm) core-shell nanogels dispersed in aqueous trimethylamine N-oxide (TMAO) solutions by means of small-angle X-ray scattering and X-ray photon correlation spectroscopy (XPCS). Upon increasing the temperature above the lower critical solution temperature of PNIPAm at 33 °C, a colloidal gel is formed as identified by an increase of I(q) at small q as well as a slowing down of sample dynamics by various orders of magnitude. With increasing TMAO concentration the gelation transition shifts linearly to lower temperatures. Above a TMAO concentration of approximately 0.40 mol/L corresponding to a 1 : 1 ratio of TMAO and NIPAm groups, collapsed PNIPAm states are found for all temperatures without any gelation transition. This suggests that reduction of PNIPAm-water hydrogen bonds due to the presence of TMAO results in a stabilisation of the collapsed PNIPAm state and suppresses gelation of the nanogel. 相似文献
19.
E. B. Gordon A. V. Karabulin V. I. Matyushenko V. D. Sizov T. N. Rostovshchikova S. A. Nikolaev E. S. Lokteva E. V. Golubina K. I. Maslakov I. N. Krotova S. A. Gurevich V. M. Kozhevin D. A. Yavsin 《High Energy Chemistry》2016,50(4):292-297
A new synthesis method based on the coagulation of metal nanoparticles, introduced by laser ablation into superfluid helium, inside of quantized vortices has been used for the fabrication of nanoweb consisting of interconnected palladium wires of a 4 nm diameter. It has been found that at temperatures above 523 K, the Pd nanoweb effectively catalyzes the oxidation of CO with molecular oxygen. Temperature cycling leads to a shift of Pd nanoweb activity to lower temperatures. The catalytic action of the Pd nanoweb has been compared to that of Pd nanoparticles with a diameter of about 2 nm prepared by laser electrodispersion. 相似文献
20.
Ekaterina S. Lokteva Vera V. Shishova Nikolay N. Tolkachev Andrey N. Kharlanov Konstantin I. Maslakov Alexey O. Kamaev Igor Yu. Kaplin Irina N. Savina Elena V. Golubina 《Molecules (Basel, Switzerland)》2021,26(1)
A mesoporous support based on silica and zirconia (ZS) was used to prepare monometallic 1 wt% Pd/ZS, 10 wt% Fe/ZS, and bimetallic FePd/ZS catalysts. The catalysts were characterized by TPR-H2, XRD, SEM-EDS, TEM, AAS, and DRIFT spectroscopy of adsorbed CO after H2 reduction in situ and tested in hydrodechlorination of environmental pollutant 4-chlorophelol in aqueous solution at 30 °C. The bimetallic catalyst demonstrated an excellent activity, selectivity to phenol and stability in 10 consecutive runs. FePd/ZS has exceptional reducibility due to the high dispersion of palladium and strong interaction between FeOx and palladium, confirmed by TPR-H2, DRIFT spectroscopy, XRD, and TEM. Its reduction occurs during short-time treatment with hydrogen in an aqueous solution at RT. The Pd/ZS was more resistant to reduction but can be activated by aqueous phenol solution and H2. The study by DRIFT spectroscopy of CO adsorbed on Pd/ZS reduced in harsh (H2, 330 °C), medium (H2, 200 °C) and mild conditions (H2 + aqueous solution of phenol) helped to identify the reasons of the reducing action of phenol solution. It was found that phenol provided fast transformation of Pd+ to Pd0. Pd/ZS also can serve as an active and stable catalyst for 4-PhCl transformation to phenol after proper reduction. 相似文献