Browsing by Author "Maroto-Valer, M. Mercedes"

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Ceria Promoted Deoxygenation and Denitrogenation of Thalassiosira Weissflogii and Its Model Compounds by Catalytic In-Situ Pyrolysis
(Elsevier Sci Ltd, 2016) Aysu, Tevfik; Maroto-Valer, M. Mercedes; Sanna, Aimaro
Pyrolysis of microcrystalline cellulose, egg white powder, palm-jojoba oils mixtures Thalassiosira weissflogii model compounds was performed with CeO2 at 500 degrees C, to evaluate its catalytic upgrading mechanism. Light organics, aromatics and aliphatics were originated from carbohydrates, proteins and lipids, respectively. Dehydration and decarboxylation were the main reactions involved in the algae and model compounds deoxygenation, while nitrogen was removed as NH3 and HCN. CeO2 increased decarbonylation reactions compared to in absence of catalyst, with production of ketones. The results showed that the catalysts had a significant effect on the pyrolysis products composition of T. weissflogii. CeO2, NiCeAl2O3 and MgCe/Al2O3 catalysts increased the aliphatics and decreased the oxygen content in bio-oils to 6-7 wt% of the algae starting O-2 content. Ceria catalysts were also able to consistently reduce the N-content in the bio-oil to 20-38% of that in the parent material, with NiCe/Al2O3 being the most effective. (C) 2016 Elsevier Ltd. All rights reserved.
Effects of Titania Based Catalysts on In-Situ Pyrolysis of Pavlova Microalgae
(Elsevier Science Bv, 2017) Aysu, Tevfik; Ola, Oluwafunmilola; Maroto-Valer, M. Mercedes; Sanna, Aimaro
Pavlova microalga was pyrolysed in presence of titania based catalysts in a fixed bed reactor at various temperatures. The effects of catalysts on Pavlova microalga pyrolysis were investigated. A large fraction of the starting energy (similar to 63-74% daf) was recovered in the bio-oils when the catalysts were used. The bio-oil yield was 20% higher in presence of Ni/TiO2 (22.55 wt%) at 500 degrees C. The High Heating Values of the produced bio-oils were in the range of similar to 35-37 Mykg and suffered strong deoxygenation, with O content (% daf) diminished from 51 wt% to similar to 9-12 wt%. The H-1 Nuclear Magnetic Resounance and Gas Chromatography Mass Spectrometry suggested that the titania catalysts enlarged the aliphatics and aromatic compounds and decreased oxygenates in the bio-oils. Ni/TiO2 had the greatest activity in increasing aliphatic protons (60%) and decreasing coke formation. Its enhanced cracking activity was due to its higher availability on the catalyst surface, compared to Co and Ce, and to strong interaction between Ni and TiO2 support. Despite the fact that the bio-oils were partially de-nitrogenated, the N-content still represent a major limitation for their use as bio-fuels without further upgrading. (C) 2017 Published by Elsevier B.V.