The permeability of a 0.175 mm thick Pd-Ag tubular membrane to pure H2 and binary mixtures of H2/CO or H2/CO2 was studied. The tests were performed in a wide range of temperature (523-723 K) and pressure (200-800 kPa).Pure H2-permeation through a dense metal membrane is described by the Sieverts' law. However, it was already found that the H2 permeation does not follow the Sieverts' law when other components are present in the feed and namely CO or CO2. In this work, it is proposed a new permeation model based on the Sieverts' law considering: i) the mass transfer resistance due to the surface effects and ii) the barrier effect due to the presence of either CO or CO2. The model was successfully validated against experimental data of hydrogen permeation for binary (H2/CO and H2/CO2) experiments for every working temperature and pressure.
Two types of catalysts were synthesized and used in the Water Gas Shift Reaction (WGSR): Rh/La 2 O 3 and Rh/ La 2 O 3 -SiO 2 . The fresh and used catalysts were characterized through X-ray diffraction (XRD), laser raman spectroscopy (LRS), Fourier transform infrared (FTIR) spectroscopy, and X-ray photoelectron spectroscopy (XPS). The stability tests performed at 673 K (50 h time-on-stream) showed that the Rh/La 2 O 3 slowly deactivated while Rh/La 2 O 3 -SiO 2 exhibited high stability at least for 50 h on stream. The instrumental techniques offered some clues to explain the possible causes of deactivation of one formulation and the high stability of the other. The latter catalyst was more active than most high-temperature formulations reported in the literature. The kinetic measurements were made at atmospheric pressure and reaction temperatures between 598 and 723 K. The results obtained were fitted by a LangmuirÀHinshelwood mechanism assuming that the rate-determining step was the surface reaction of adsorbed CO and H 2 O. The parity plot showed a good correlation between the experimental and calculated reaction rates. The thermal parameters calculated with this model were all physically consistent. They were compared to kinetic, thermodynamic, and calculated data reported in the literature.
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