198 research outputs found
Mathematical simulation of hydrogen production via methanol steam reforming using double-jacketed membrane reactor
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Photoreduction of CO2 in an optical-fiber photoreactor: Effects of metals addition and catalyst carrier
No full textPhotoreduction of CO2 over Ruthenium dye-sensitized TiO2-based catalysts under concentrated natural sunlight
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In situ FTIR study of photocatalytic NO reaction on photocatalysts under UV irradiation
No full textThe photocatalytic reaction of nitric oxide (NO) on TiO2 and transition metal-loaded M (Cu, V, and Cr)/TiO2 catalysts was studied using in situ
FTIR spectroscopy under UV irradiation. TiO2 and M/TiO2 catalysts were prepared by the sol–gel method via controlled hydrolysis of titanium
(IV) butoxide. Copper, vanadium, or chromium was loaded onto TiO2 during the sol–gel procedure. After treatment at 500 ◦C under air flow,
a large amount of surface peroxo species and OH groups were detected on the TiO2 and M/TiO2 catalysts. Nitric oxide was adsorbed on TiO2 and
M/TiO2 in the form of bidentate nitrites and nitrates by reacting with OH groups, peroxo, or M=O species. In addition, NO can also be adsorbed
on Mn+ in the form of nitrosyls. Under UV irradiation, bidentate nitrite was oxidized to either monodentate or bidentate nitrate. Such oxidation
was suggested to be induced by superoxo species generated by oxidizing peroxo species via photogenerated holes. The existence of nitrosyls
deferred the oxidation of nitrites to nitrates due to the prior oxidation of nitrosyls by superoxo. The XRD and UV–vis spectra showed that the
structures and the abilities of absorbing UV light of all catalysts were not influenced by the photocatalytic NO reaction. Possible mechanisms
were proposed for the photocatalytic NO oxidation on TiO2 and M/TiO2 based on the intermediates found from the in situ FTIR study
Visible-light response Cr-doped TiO2-XNX photocatalysts
No full textChromium (Cr) and nitrogen (N)-doped titania (TiO2) was prepared using sol–gel method and ammonia thermal treatment. TiO2 co-doped
with Cr and N showed intense absorption bands in the visible-light region. The X-ray photoelectron spectroscopy (XPS) detected chromium
and nitrogen ions on the surface of catalysts, but no diffractive peak of chromium oxide or titanium nitride was observed in X-ray diffraction
(XRD) spectra. The analysis of X-ray absorption near edge spectroscopy (XANES) indicated either Cr3+ or Cr4+ chemical status implying that
chromium either substituted Ti4+ site or locally was isolated on the surface of TiO2. The photocatalytic activity was evaluated by the degradation
of methylene blue (MB) and isopropyl alcohol (IPA) under visible-light (>460 nm) irradiation using blue-light emitted diode. The rate constants
of MB and IPA photodegradation with N-doped TiO2 were 7.7 and 80 mol l−1 h−1 g−1, which were much higher than those with pure TiO2, 0.15
and 0 mol l−1 h−1 g−1, respectively. The Cr and N co-doped TiO2 showed less photoactivity than either Cr or N-doped TiO2 due to the extra
imperfection of TiO2 lattice during preparation
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