Abstract
AbstractIrradiations of Ni/TiO2 catalyst by UV in hydrogen at 77 K produced not only Ni+ ions on the catalyst surface, but also Ni3+ and Ti3+ species in bulk or near the interface between nickel and titania. These photo‐generated species were detected and characterized by low temperature electron paramagnetic resonance (EPR) spectroscopy. Relative spin concentrations of the photogenerated paramagnetic species (Nin+ and Ti3+) varied with the nickel content in titania. A high nickel content in the sample resulted in a high peak intensity ratio of Nin+ to Ti3+. It was found that the photoinduced self‐redox reaction of Ni2+ ions to form Ni+ and Ni3+ ions has a priority over the photoreduction of Ti4+ to Ti3+ ions. The characteristic EPR spectrum of the Ni3+ (3d7) ions with g1 = 2.268, g2 = 2.237, and g3 = 2.045 indicates that the Ni3+ ions are most likely located in the substitutional sites of TiO2, possibly near the surface rutile phase. The Ni+ species (3d9) with g4 = 2.130 and g1 = 2.063 are on the surface of TiO2. Both Ni+ and Ni3+ ions are quite stable in hydrogen. The Ni3+ ions seem to be responsible for anchoring the nickel ions onto titania and stablizing the Ni+ species on the surface. The Ni+ ions are thus free from oxygen poisoning and still show a high activity toward olefin oligomerization.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: 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.
