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Role of oxygenates and effect of operating conditions in the deactivation of a Ni supported catalyst during the steam reforming of bio-oil

Abstract

This work investigates the correlation of the reaction conditions (temperature and steam-to-carbon ratio (S/C)) and the reaction medium composition with the deactivation behavior of a Ni/La2O3-αAl2O3 catalyst used in the steam reforming of bio-oil, aiming the sustainable hydrogen production from lignocellulosic biomass. The reaction was performed in an in-line two-step system, consisting of a thermal treatment of bio-oil at 500 °C for retaining the thermal pyrolytic lignin, and in-line steam reforming of remaining oxygenates in a fluidized bed catalytic reactor. The reforming step was conducted at 550 and 700 °C and S/C ratio of 1.5 and 6. Fresh and deactivated catalyst samples were characterized using XRD, SEM, TEM, TPO, XPS, Raman and FTIR spectroscopies. The catalyst deactivation is mainly due to the amorphous and encapsulating coke deposition, whose formation is attenuated when both temperature and S/C ratio are increased. Although the highest catalyst stability is attained at 700 °C and/or S/C ratio of 6, Ni sintering is noticeable at these conditions. The encapsulating coke is highly oxygenated, in contrast with the more aromatic and condensed nature of filamentous coke. Based on the correlation between the composition of the coke and the reaction medium, it was established that bio-oil oxygenates are the precursors of the encapsulating coke, particularly phenols and alcohols, whereas CO and CH4 are the possible precursors of the coke fraction constituted by filaments, whose contribution to catalyst deactivation is hardly significant.

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Publication details

The article was received on 15 May 2017, accepted on 13 Jul 2017 and first published on 14 Jul 2017


Article type: Paper
DOI: 10.1039/C7GC01432E
Citation: Green Chem., 2017, Accepted Manuscript
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    Role of oxygenates and effect of operating conditions in the deactivation of a Ni supported catalyst during the steam reforming of bio-oil

    A. Ochoa, B. Aramburu, B. Valle, D. Resasco, J. Bilbao, A. G. Gayubo and P. Castaño, Green Chem., 2017, Accepted Manuscript , DOI: 10.1039/C7GC01432E

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