The kinetics of oxidation of allyl alcohol to glycidol in the presence of extruded titanium silicalite was investigated. Based on the experimental data obtained, a kinetic model of the process was ...developed and the activation energies of the target and side reactions, the rate constants and the adsorption equilibrium were determined. Testing of the process of allyl alcohol epoxidation was carried out and the adequacy of the proposed kinetic model was evaluated at the bench laboratory installation of continuous action.
Graphic Abstract
The structure of flows and the efficiency of mass transfer in columns filled with a hydrophobic Pt/SDVB catalyst and a hydrophilic packing Helipak C 3 × 3 × 0.2 mm were investigated. Based on the ...model reaction of phase isotopic exchange between liquid water and its vapors, the importance of the method of preliminary preparation of the column for the efficiency of mass transfer is shown. The influence of hydrodynamic conditions (presence of gas counterflow, superficial liquid mass flow rate, column loading and preparation method) on the structure of flows in the catalyst-packing bed has been studied by the method of non-stationary pulse injection of a tracer. It is shown that replacement of a packed bed consisting of catalyst-packing layers with a mixed bed of catalyst and packing leads to more even distribution of the flow across the cross section and the height of the column.
—
Adhesion/decohesion processes on the surface of dense metallic diffusion membranes in direct contact with hydrogen have been studied by scanning electron microscopy and energy dispersive X-ray ...spectroscopy. The elemental composition of the alloys has been determined to be (wt %) Pd
93
Y
7
, Pd
100 –
х
Pb
х
(
х
= 5, 20), and Pd
94
Ru
6
. We have revealed Pb emission from the surface of the Pd
100 –
х
Pb
х
membranes and Pb adhesion to the surface of the Pd
93
Y
7
membranes. No adhesion of yttrium particles to the surface of the palladium–lead membranes has been detected. The surface of Pd
94
Ru
6
alloy has good stability to adhesion/decohesion processes.
The structure of radiation defects – tracks is studied in a 1 µm thick YBa
2
Cu
3
O
6 + δ
layer in composite tapes irradiated with Xe and Kr ions with energies in the range 0.1–0.8 MeV/nucleon. It is ...shown that the irradiation of YBa
2
Cu
3
O
6 + δ
with ions of various energies leads to the creation of continuous (highest ion energies) and discontinuous ion tracks (created by ions with intermediate energies) with an amorphous structure. The density of the material inside the track is almost two times lower than the density of the pristine YBa
2
Cu
3
O
6 + δ
crystal. It has been found that almost spherical fragments of discontinuous tracks with a diameter of about 5 nm are most effective for immobilization of vortex lines and contribute to an increase in the critical current density in magnetic fields up to 9 T in the temperature range 4.2–77 K.
Some features of the structure formation and mechanical characteristics of dispersion-reinforced copper substrate tapes have been studied during their manufacture. The change in the structure of the ...matrix phase and the properties of reinforcing particles dispersed in it have been investigated after col rolling and recrystallization annealing. Particular attention is paid to the possible impact of the dispersed phase on the texture of metallic substrate tapes, since the perfect texture of a tape ensures a further growth of buffer and superconducting layers on it. It is shown that alloying of the copper matrix with iron particles does not degrade the tendency to formation of a sharp cube texture.
Studies of the effect of transition metals on the phase composition and electric and dielectric properties of diamond-like silicon–carbon films fabricated by plasma chemical decomposition of ...poly(phenylmethylsiloxane) are conducted. Frequency, temperature, and concentration dependences of the specified properties are obtained. It is shown that electrical conductivity continuously increases with the increase in the concentration of the metal and the concentration dependences of dielectric permeability and dielectric loss tangent have a minimum at the concentration of the metal of 0.5–2 at %. The possible reasons for this phenomenon are analyzed.
Systematic studies of second-generation high-temperature superconducting wires with Gd excess relative to the stoichiometric GdBa
2
Cu
3
O
7
composition are reported. It has been revealed that ...filamentary defects in the form of non-superconducting Gd
2
CuO
4
phase located along the ab plane are formed during film growth. These inclusions lead to a change in the pinning mechanism of the vortex structure, due to which the peak of the critical current at +15% Gd is clearly observed.
Separation factors for ideal gas phase isotopic exchange reactions between water vapor and hydrogen were calculated for deuterium-protium exchange in the presence of trace amounts of tritium using ...adiabatic correction factors calculated by Bardo and Wolfsberg. The results obtained support the conclusions made by Bardo and later by Rolston that the application of adiabatic correction factors leads to slightly lower and more precise values of equilibrium constants or separation factors in comparison to separation factors straightforwardly calculated from the isotopic partition function ratios published by Bron, Chang and Wolfsberg. The difference for protium-trace tritium exchange is relatively low, at 333 K it amounts to 2.2%. Comparison with published experimental data on tritium exchange in the low deuterium concentration limit shows that the corrected values better reproduce experiment at least at temperatures below 383 K confirming earlier conclusions made for protium-deuterium exchange. Results are given in the form of 2D polynomial fits over wide range of deuterium concentration and temperature that is useful for the application of them in equation-oriented process modeling systems for the modeling of CECE process.
The results of developing a software package for automated orientational mapping based on diffraction data are presented. The experimental module of the software is responsible for the communication ...with a microscope and acquisition of diffraction maps. The analytical module automatically processes and solves diffraction patterns obtained by transmission electron microscopy. The test data analysis has shown the diffraction mapping results to be consistent with the model data.
