European Reviews of Chemical Research

102-111

Authors: Junjie Chen

Surface ignition and extinction of very fuel-lean hydrogen-air mixtures on platinum surfaces were modeled using a detailed surface kinetic mechanism and transport phenomena. A stagnation-point flow geometry was employed to study the effect of heat flux, flow velocity, and composition on the surface ignition and extinction. The temperature and concentration on platinum surfaces as well as the coverage of surface species were also explored to evaluate the role of gas-phase chemistry. It was shown that the platinum surface can be poisoned by different adsorbates, and the dynamic process of surface ignition and extinction is associated with a phase transition from one poisoning species to another. For certain temperatures, multiple poisoned states of the surface coexist. Comparisons of simulations with experiments were carried out, and the results revealed that the self-inhibition of hydrogen surface ignition is caused by poisoning of platinum by atomic hydrogen.

122-129

Authors: Tatiana V. Vinogradova, Irina A. Glukhova, Larisa N. Maskaeva, Vyatcheslav F. Markov

The article considers kinetic aspects study of hydrochemical deposition of solid phase Ag2S from solutions containing silver nitrate, ammonium hydroxide and sodium citrate at temperatures 303-343 K in the conditions of the spontaneous formation of solid phase. The authors conclude that: 1. Particular kinetic orders are defined on all components of reaction mixture and activation energy of this process is 37 kJ/mole. 2. In the certain concentration limits formal kinetic equation was derived for the rate of conversion of silver salt into silver sulfide that allows to provide the regulation of the rate of silver sulfide phase formation in the investigated reaction mixture purposefully.