Abstract
Doping of alumina, yttria and zeolite 4A with small quantities of palladium (down to 0.025%) was done. It was shown that these oxides, which do not normally absorb hydrogen, after the doping acquire a considerable capacity for hydrogen absorption. The sorption of hydrogen is occurring by the spill-over effect from metallic palladium to the oxide. The process is exothermal, taking place in two stages between 60 and 350 °C. Activation energies of the first stage range from 120 to 167 kJ mol−1 and for the second one from 20 to 30 kJ mol−1. After cooling to room temperature in hydrogen flow, the samples are able to absorb considerable quantities of oxygen which reacts exothermally with the previously formed hydride. On next exposition to hydrogen, a vigorous reaction of it with the adsorbed oxygen is taking place already at room temperature. Enthalpies of hydrogen absorption, — ΔH, are of the order of 10 kJ g−1, showing a tendency of increase after repeated exposures to hydrogen.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.