Fast pyrolysis can convert many different types of biomass into liquid bio-oils, but these oils typically have to be upgraded to obtain the required properties for their use as chemicals and fungible fuel additives. Hydrodeoxygenation (HDO) achieves this by replacing oxygen containing functional groups with hydrogen. In principle, water is formed as the only by-product. The process provides oils with reduced reactivity and corrosiveness and increases the energy density of the oil. Among the most promising classes of HDO catalysts are zeolites that contain noble or transition metal sites. However, the usefulness of these catalysts is limited due to deactivation within a few hours on stream. In most studies, coking is assumed to be the cause of deactivation, but detailed studies of this issue are rare.<br/><br/>In this presentation, we show that additional paths contribute significantly to the deactivation. Bifunctional aromatics, like catechol and guaiacol, can strongly adsorb on the surface forming rigid surface species, so-called roadblocks [1]. The roadblocks drastically reduce access to metal sites and acid sites inside and outside the micropores of the zeolite even when they are only present in limited quantities. In addition, enhancement of dealumination by oxygenates will be discussed. Based on these results, it will be possible to design HDO catalysts and processes with significantly improved efficiency.

Deactivation of zeolite catalysts during hydrodeoxygenation of aromatic oxygenates

255th National Meeting (2018)

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