Pd/γ-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> catalysts on cellular supports for VOC vapor neutralization

The results from investigating the influence of temperature, concentration, and flow rate on the catalytic oxidation of vapors of volatile organic compounds (VOCs) in the presence of Pd/γ-Al₂O₃ catalyst on cellular supports are presented. The activity of Pd/γ-Al₂O₃ catalysts on ceramic and metal monolith supports with a cellular structure during the catalytic neutralization of VOC (ethanol, ethyl acetate) vapors under laboratory conditions was determined, and the most stable catalyst for the preliminary study of a large batch was chosen. A pilot unit was created to test a large batch of cellular monolith catalyst in neutralizing VOC vapors under conditions of flexographic production. It was established that a high rate of conversion (> 99 %) was achieved for VOC concentrations of 0.5 g/m³ at space velocities of up to ∼10⁴ h⁻¹, and for VOC concentrations of 5.0 g/m³ at space velocities of up to ∼5 × 10⁵ h⁻¹. The change in the activity of the catalysts on metal (nickel alloyed by aluminum) and ceramic cellular supports in service was investigated. After 300–500 min of operation, virtually complete deactivation of catalyst on a metal support was observed, accompanied by the formation of nickel oxide and acetate. Pilot unit tests with catalyst on cellular supports having a volume of 14.5 l in neutralizing the ventilation exhausts of flexographic production confirmed the possibility of more than 90% conversion at VOC concentrations of ∼0.1 g/m³ and more than 97% at VOC concentrations of over 1 g/m³. A consistently high conversion of VOC was observed during a 100 h test of the pilot unit. A system for recovering the heat released during VOC oxidation lowers the operating costs of the pilot unit.     

Impedance-matching arrangement for microwave transponder operating over plurality of bent installations of antenna

An impedance-matching arrangement is considered for an essentially flexible RFID transponder that can operate over a plurality of its bent installations. The novel structure matches the actual complex impedance of the transponder's application-specific integrated circuit to the input impedance of the antenna over different forms of mechanical deformation and thereby improves overall performances of the passive identification system.     

Transformation of CH4 and liquid fuels into syngas on monolithic catalysts

Active components comprised of fluorite-like Ln_x(Ce_0.5Zr_0.5)_1−xO_2−y (Ln = La, Pr, Sm) and perovskite-like La_0.8Pr_0.2Mn_0.2Cr_0.8O₃ mixed oxides and their composites with yttria-doped zirconia (YSZ) promoted by precious metals (Pt, Ru) and/or Ni were supported on several types of heat-conducting substrates (compressed Ni-Al foam, Fecralloy foil or gauze protected by corundum layer, Cr-Al-O microchannel cermets, titanium platelets protected by oxidic layer) as well as on honeycomb corundum monolithic substrate. These structured catalysts were tested in pilot-scale reactors in the reactions of steam reforming of methane, selective oxidation of decane and gasoline and steam/autothermal reforming of biofuels (ethanol, acetone, anisole, sunflower oil). Applied procedures of supporting nanocomposite active components on monolithic/structured substrates did not deteriorate their coking stability in real feeds with a small excess of oxidants, which was reflected in good middle-term (up to 200 h) performance stability promising for further up-scaling and long-term tests. Equilibrium yield of syngas at short contact times was achieved by partial oxidation of decane and gasoline without addition of steam usually required to prevent coking. For the first time possibility of successive transformation of biofuels (ethanol, acetone, anisole, sunflower oil) into syngas at short contact times on monolithic catalysts was demonstrated. This was provided by a proper combination of active component, thermal conducting monolithic substrates and unique evaporation/mixing unit used in this research.     

A hydrogen-sensitive structure based on semi-insulating gallium arsenide

The response characteristics of a simple hydrogen-sensitive structure based on semi-insulating single crystal gallium arsenide with planar palladium electrodes deposited onto the oxidized substrate surface are studied. It is demonstrated that such structures exhibit a fast response to hydrogen present in the gas phase. The sensitivity can be increased by growing, prior to the electrode formation, an intermediate epitaxial GaAs film with built-in strained quantum-confined layers of InGaAs and InAs onto the semi-insulating GaAs substrate.     

Physical properties of metal–insulator–semiconductor structures based on <Emphasis Type="Italic">n</Emphasis>-GaAs with InAs quantum dots deposited onto the surface of an <Emphasis Type="Italic">n</Emphasis>-GaAs layer

The properties of metal–insulator–semiconductor (MIS) structures based on n-GaAs in which silicon oxide and yttria-stabilized zirconia and hafnia are used as the insulator containing InAs quantum dots, which are embedded at the insulator/n-GaAs interface, are investigated. The structures manifest the resistive switching and synaptic behavior.     

The Surface Chemistry of Acetic Acid on Pd{111}

XPS, temperature-programmed reaction and HREELS have been used to study the adsorption and reactions of acetic acid on Pd{111}. At 170 K the adsorbed monolayer contains intact and dissociated acetic acid molecules, the latter consisting of a mixture of bidentate acetate and another species tentatively identified as monodentate acetate. The monodentate acetate appears to resemble closely the acetate species observed under reaction conditions at the surface of a pure palladium vinyl acetate synthesis catalyst. Thermal decomposition of the adsorbate yields CO₂, H₂O, CO, H₂ and carbon. The associated processes may be rationalised in terms of two reaction channels, one due to the monodentate and the other due to the bidentate acetate.     

Self-organization of nanoislands on the surface of silicon and gallium arsenide single crystals stimulated by spatially periodic laser radiation fields

Four interfering laser beams acting upon the surface of silicon and gallium arsenide single crystals stimulate the self-organization of nanoislands, which is manifested by the development of processes controlling the size of islands in a two-dimensional periodic structure formed on the sample surface. The influence of the polarization of interfering beams on the character of this self-organization has been studied. Islands with lateral dimensions from 60 to 100 nm and a height of 6–12 nm have been obtained. The lateral dimensions of nanoislands are 5–10 times smaller than the period of a standing wave of the laser radiation field, which is explained by the influence of elastic stresses developed at the crystal surface.     

Honeycomb catalysts for clean-up of diesel exhausts based upon the anodic-spark oxidized aluminum foil

The technology of the aluminum foil anodic spark oxidation in the water-based electrolytes has been applied to form strongly adhering protective alumina layer at the surface. Basic features of the oxidation were studied by SEM and XRD. Secondary supports, promoters and modifiers including rare-earth elements were used to increase the thermal stability of these composites up to 900°C. These materials were assembled as thin wall honeycomb supports loaded with a number of active components. The catalysts were tested in the reactions of CO and CH_x oxidation, NO_x selective reduction by hydrocarbons and demonstrated a high performance and a low pressure drop at high space velocities. City diesel buses field tests of converters equipped with those catalysts demonstrated their high and stable performance in clean-up of exhausts from SOF, CO, gaseous hydrocarbons and NO_x.     

Hydrogen sensitivity of a silicon Schottky diode increased by modification of the semiconductor surface microrelief

A nearly atomically smooth semiconductor surface in a Schottky diode based on the palladium-oxide-silicon structure is modified by treating with a selective etchant. It is shown that the appearance of a developed microrelief (with an average roughness of 22–32 nm and a fractal dimension of 2.33–2.40) leads to a decrease in the barrier height of the Pd-Si junction, an increase in the density of states at the oxide-silicon boundary, and a considerable (an order of magnitude) growth in the sensitivity with respect to hydrogen detected by a change in the diode reverse current.     

Quantum Size Effects in Catalysis by TiO2/Platinum: The Switch from Partial Oxidation to Partial Hydrogenation of Styrene

The promotional effects of CO₂ and Ni were studied on Co/Mn/Br catalyst in the liquid-phase oxidation of p-xylene to terephthalic acid using molecular oxygen as an oxidant and acetic acid as a solvent individually as well as in combination. The enhanced activity of Co/Mn/Br catalyst was observed on both CO₂ and Ni promoters independently and also in combination. The activity enhancement in the combination of CO₂ and Ni promoters on this catalyst is found to be remarkable.