Oscillatory Rates of Heat Evolution during Sorption of Hydrogen in Palladium
| Autor: | Jerzy Haber, E. Lalik, Aleksander J. Groszek |
|---|---|
| Rok vydání: | 2008 |
| Předmět: |
Isothermal microcalorimetry
Hydrogen Analytical chemistry chemistry.chemical_element Thermodynamics Sorption Mole fraction Isothermal process Surfaces Coatings and Films Electronic Optical and Magnetic Materials Volumetric flow rate General Energy chemistry Physical and Theoretical Chemistry Total pressure Palladium |
| Zdroj: | The Journal of Physical Chemistry C. 112:18483-18492 |
| ISSN: | 1932-7455 1932-7447 |
| DOI: | 10.1021/jp805414a |
| Popis: | The oscillatory character of sorption of H2 in Pd has been observed for the first time by measuring the oscillating rate of heat evolution accompanying the reaction. The process was investigated by using isothermal flow-through microcalorimetry with in situ calibration to monitor the sorption of gaseous hydrogen in palladium powder at 105 °C from a mixture of H2/N2 at various H2 molar fractions and flow rates. The microcalorimetric measurements made it possible to determine the conditions at which the well-known reaction of H2 and Pd reaches the oscillatory regime. One of these conditions is that the total pressure of the gas phase within the system needs to be lowered initially to ∼600 hPa before admitting the reaction mixture. The oscillatory behavior occurs then at the molar fraction of H2 ranging from 0.83 to 0.92 and the flow rate of the reaction mixture between 1.2 and 2.2 cm3/min. The oscillations are nonsinusoidal, periodic, or quasiperiodic with the period length varying from 50 to 30 s. The freq... |
| Databáze: | OpenAIRE |
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