Investigation into photoreduction of vanadium ions on silica gel and porous glass surface using electron spin resonance and optical spectroscopy. Communication 2. Photoreduction by hydrogen

Photoreduction in H2 atmosphere of V5+ ions deposited on silica gel powder and porous glass was investigated at 77 and 300 K. Ions of V4+ are formed selectively following light irradiation with ν < 26000 cm-1 corresponding to a long-wave end of the band with O2- → V5+ charge exchange. Ions of V4+ and V3+ represent photoreduction products formed in irradiation with unfiltered light of a mercury lamp. The latter are supposed to be formed due to a gradual absorption of two photons. Following a continuous irradiation the share of V4+ ions in photoreduced samples decreases. Coordination of reduced ions and its changes due to the sample warming up under vacuum and the H2O, C2H4, NH3 and CO adsorption were studied by the methods of electron spin resonance and optical spectroscopy. Products of V3+, V4+ ion interaction with O2 and N2O were investigated