Several TiO 2 based semiconductors with different Pt loadings are prepared using incipient impregnation, wet impregnation and the sol-gel method. These photocatalysts are evaluated in the Photo-CREC-Water II Photoreactor for hydrogen production via water dissociation, using an organic renewable scavenger (ethanol). Results obtained show the influence of the photocatalyst preparation in the production of hydrogen and in the observed quantum yields. Furthermore, it is established that the reaction networks leading to hydrogen production, using various photocatalysts, share common features. This analysis is developed by both identifying and quantifying different chemical species and their changes with irradiation time. Key species in this oxidation-reduction network are hydrogen, hydrogen peroxide, ethanol, methane, ethane, acetaldehyde and carbon dioxide. On this basis, it is shown that under an inert gas atmosphere, ethanol consumption is sub-stoichiometric. This points towards simultaneous ethanol consumption and the formation of the ethanol scavenger.
Miscanthus, an invasive crop, has recently gained attention as an emerging energy crop because of certain traits like fast growth, high yield, ability to grow in marginal land, and resistance to extreme weather conditions. In this work, Miscanthus was selected as the feedstock for fast pyrolysis in a mechanically fluidized bed reactor at variable temperatures (400 C, 450 C, and 500 C) and vapour residence times (1.4, 2.7, and 5.2 seconds). Fast pyrolysis performed at 450 C with 1.4 seconds of vapour residence time gave the highest yield of biooil (>50 wt%). Biochar obtained at different pyrolysis temperatures was activated at 900 C for 1.5 hours under CO 2 atmosphere to enhance its value as a potential adsorption agent for pollutants. Several physicochemical characterization techniques were used to study the bio-oils, biochars, and activated biochars obtained from the pyrolysis of Miscanthus. The absorption of methylene blue as a model dye was done to evaluate the performance of activated biochar vs the biochar precursors. Both pyrolysis and physical activation complemented each other as new technologies for energy extraction and material synthesis from Miscanthus.
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