Cobalt doped TiO2: A stable and efficient photocatalyst for continuous hydrogen production from glycerol: Water mixtures under solar light irradiation
| Autor: | Kannekanti Lalitha, Muthukonda Venkatakrishnan Shankar, Gullapelli Sadanandam, Valluri Durga Kumari, Machiraju Subrahmanyam |
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| Rok vydání: | 2013 |
| Předmět: |
inorganic chemicals
Aqueous solution Materials science Renewable Energy Sustainability and the Environment Inorganic chemistry Energy Engineering and Power Technology chemistry.chemical_element Condensed Matter Physics Catalysis chemistry.chemical_compound Fuel Technology chemistry X-ray photoelectron spectroscopy Photocatalysis Glycerol Irradiation Cobalt Hydrogen production |
| Zdroj: | International Journal of Hydrogen Energy. 38:9655-9664 |
| ISSN: | 0360-3199 |
| DOI: | 10.1016/j.ijhydene.2013.05.116 |
| Popis: | Glycerol is the main by-product during the trans-esterification of vegetable oils to biodiesel. In this study, we investigate the process of photocatalytic hydrogen production from glycerol aqueous solution, with the use of cobalt doped TiO2 photocatalyst under solar light irradiation. Cobalt doped TiO2 photocatalysts are prepared by impregnation method and these catalysts are characterized by XRD, EDAX, DRS, TEM, EPR and XPS techniques. DRS studies clearly show the expanded photo response of TiO2 into visible region on impregnation of Co2+ ions on surface of TiO2. XPS studies also show change in the binding energy values of O1s, Ti 2p and Co 2p, indicating that Co2+ ions are in interaction with TiO2. Maximum hydrogen production of 220 μ mol h−1 g−1 is observed on 2 wt% cobalt doped TiO2 catalysts in pure water under solar irradiation. A significant improvement in hydrogen production is observed in glycerol: water mixtures; and maximum hydrogen production of 11,021 μ mol h−1 g−1 is obtained over 1 wt% cobalt doped TiO2 in 5% glycerol aqueous solutions. Furthermore, to evaluate some reaction parameters such as cobalt wt% on TiO2, glycerol concentration, substrate effect (alcohols) and pH of the solution on the hydrogen production activity are systematically investigated. When the catalysts are examined under UV irradiation, a 3–4 fold increase in activity is observed where this activity seems to decrease with time; however, a continuous activity is observed under solar irradiation on these catalysts. The decreased activity could be ascribed the loss of cobalt ions under UV irradiation, as evidenced by EDAX and TEM analysis. A possible explanation for the stable and continuous activity of cobalt doped TiO2 photocatalysts under solar irradiation is proposed. |
| Databáze: | OpenAIRE |
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