Alexander V. Kulikov

Quantitative temperature mapping within an operating catalyst by spatially resolved 27Al NMR.

Spatially resolved NMR is employed to quantitatively map the temperature of a solid catalyst under operating conditions during H(2) oxidation with O(2) over Pt/γ-Al(2)O(3). As this new non-invasive in situ technique utilizes the (27)Al NMR signal of the solid phase, it is suitable for catalyst temperature mapping in both liquid- and gas-phase heterogeneous catalytic processes.

A new concept reactor for hydrocarbon hydrogenation in the reactive evaporation mode

Abstract A new gas–liquid–solid reactor is presented whose concept is based on the coupling of liquid imbibition, evaporation, and an exothermic gas-phase reaction within a non-permselective catalytic porous membrane. Because of enhanced thermal conductivity of the sintered metal catalyst support and liquid flow re-circulation, it is possible to eliminate hot spots and runaways and to maintain high productivity of the reactor. When vapor conversion in the membrane is high, the problem of separation of the product from the gas phase reduces to common condensation. The preliminary experiments on the α-methylstyrene (AMS) hydrogenation on the 10% (0.9% Pd/γ-Al 2 O 3 ) + 90% (80% Ni, 20% Al) membrane sintered on the tube wall are very promising, however, further investigations are required.

Catalytic heat generating element for autonomous domestic heating systems

New heat-conducting metal porous reinforced catalysts were developed to manufacture a catalytic heat generating element (CHGE) of 25 kW power. The element was subjected to thermophysical, hydraulic and ecological testing. Local temperature and gas flow rates were determined in different places of the outer catalytic bed surface. We have estimated impact of the convective and radiant transfer in total CHGE heat generation. Dynamics of CHGE startup was studied. A prototype of the catalytic water boiler supplied with a CHGE of 25 kW power was manufactured and tested. The boiler provides below yield of toxic waste: CO 5–10 ppm, NOx traces, CH4 10–20 ppm, CO2 10 vol.%, the other gases 89.5 vol.%. CHGE is promising as a device for ecologically safe heat production for household appliances.

Modeling of critical phenomena for liquid/vapor–gas exothermic reaction on a single catalyst pellet

Abstract Physical mechanisms are discussed and crude mathematical models with lumped parameters are developed, which explain the authors recent experimental data [4] , concerning temperature hysteresis and multiplicity phenomena for α-methylstyrene (AMS) liquid–vapor hydrogenation on a single catalyst pellet. The interplay between endothermic vaporization and exothermic vapor phase reaction is elucidated. The results of this study may help to develop more sophisticated models and theory of hot spots formation and runaway phenomena in trickle-bed reactors.

Simplified treatment of mass transfer for gas-phase hydrogenation/dehydrogenation of heavy compounds

Using single catalyst pellets (5 mm) 15% Ptγ–Al2O3, we experimentally studied gas-phase benzene hydrogenation at normal pressure by thermocouple measurements of gas flow and the pellet center. Temperature of gas flow was varied in the range of 20 ‡C / 350 ‡C for three molar fractions of benzene vapor (0.1, 0.2, and 0.3) mixed with hydrogen. The ignition/extinction behavior of the flow-pellet temperature rise (maximum values up to 100 ‡C/ 200 dgC) is explained by internal-external mass transport limitations of the reaction rate and reaction reversibility at high pellet temperature. A simplified pseudobinary treatment of both multicomponent intrapellet mass transfer (in bimodal porous media) and multicomponent external mass transfer (under forced convection) is proposed on the basis of the analytical estimation. The validity of the suggested approach is confirmed by comparing the experimental data for benzene hydrogenation with rigorous (multicomponent) and approximated (pseudobinary) calculations obtained by using a mathematical model of a spherically symmetric pellet. The simplified approach appears to be quite accurate for reactions A+nH2=B of hydrogenation (n>0) or dehydrogenation (n<0) of sufficiently heavy compounds, i.e. if DAH≈DBH>>DAB

Acetylene synthesis by methane pyrolysis on a tungsten wire

Acetylene synthesis conditions in methane pyrolysis on a tungsten wire heating element have been investigated. At high temperatures, methane pyrolysis yields a large amount of carbon black as small particles and carbon filaments. Carbon black practically does not form when methane is diluted with helium. At methane concentrations of 10–15% and coil temperatures of 1800–2000°C, 80% methane conversion and 80% acetylene selectivity have been attained at a contact time of a few hundredths of a second. Changing from pure methane to natural gas in the specified temperature range exerts no effect on the methane conversion and acetylene selectivity. It has been experimentally demonstrated that the reaction ceases on the gas temperature is decreased below 800°C.