Oligomerization of 1-Pentene on Zeolite Catalysts

Catalysis in Industry - The oligomerization of 1-pentene is an efficient process for producing environmentally friendly high-quality fuel components. The catalytic properties of FAU, OFF, MOR, BEA,...     

Intelligent scheduling processes and controlling workload in computing systems

Methods and algorithms of adaptive scheduling processes and workload control in computing systems are considered.     

Effect of the Products of Plasma-Chemical Transformations on the Properties of a Plasma and Its Dynamic Behavior

A glow-discharge plasma bounded by a chemically reactive surface is studied. It is shown that the investigation of the properties of such systems must take into account heterogeneous reactions and chemical feedback. A study is undertaken to explore the dynamics of attaining the steady-state values of the discharge current and the plasma glow intensity in a case where there is gas desorption from the boundary surface. A formal model of the process is proposed that takes into account the accumulation of negative ions in the bulk of the positive column of the discharge. This model enables one to qualitatively explain the experimentally observed dynamic features of a plasma.     

Influence of oxygen content on some properties of Nb3Sn tape used for superconducting transmission lines

The influence of the presence of oxygen in the Nb-Zr substrate upon some physical and mechanical properties of the Nb-ZrO₂ substrate and/or Nb₃Sn tape superconductor prepared from such a substrate has been studied. The results have shown that the Nb₃Sn grains are much finer in the case of Nb-ZrO₂, than those obtained on Nb-Zr substrate. As a result, both the electrical and mechanical properties have been substantially improved. The critical current at a field of 5 T increased by between 100 and 200 %, the alternating current losses decreased by about one order of magnitude, the tensile strength increased by about a factor of three and the microhardness value also increased by about a factor of three for oxygen contents in the range 0.03 to 0.70 wt%. The specific resistance of this substrate increased at the same time from 17 to 22 cm and the relative elongation decreased from 5 to 3 %.     

Interaction between Copper(II) Oxide and Aqueous Ammonia in the Presence of Ethylenediaminetetraacetic Acid

The interaction of copper(II) oxide with aqueous ammonia containing ethylenediaminetetraacetic acid (H₄L) is analyzed in terms of formal heterogeneous kinetics and the fractal dimension of the dissolving space. It is shown experimentally that, in the presence of H₄L, the dissolution rate of CuO grows with increasing ammonia concentration. At a fixed ammonia concentration, the dissolution rate of CuO passes through a maximum at an H₄L concentration of 8 × 10^–3mol/l. Two mechanisms of dissolution are suggested, namely, an adsorption and a redox mechanism. The adsorption mechanism involves four intermediate species and implies that the dissolution rate is a fractional rational function of the EDTA concentration. The redox mechanism takes into account the oxide/electrolyte interfacial potential. The role of the CuOHL^3–ion is elucidated, and the kinetic parameters of dissolution are derived.     

Dimerization of α-methylstyrene on high-silica zeolites

α-Methylstyrene dimerization was studied on high-silica β, ZSM-12, and TsVN zeolites. The acid properties of the zeolites were studied by IR spectroscopy. It was revealed that the catalytic properties of the zeolites in α-methylstyrene dimerization depend on both the acidic and structural characteristics of the catalysts. The highest activity in the reaction was exhibited by zeolite β, as the maximum amount of acid sites were found in its structural units (inside channels, on the outer surface). Zeolite ZSM-12 had the highest selectivity for linear dimers.