In situ catalytic fast pyrolysis of crude and torrefied Eucalyptus globulus using carbon aerogel-supported catalysts

Nickel and iron supported on thermostable cellulose-derived carbon aerogels (CAG), were used for the catalytic fast pyrolysis (CFP) of crude and torrefied Eucalyptus globulus. Pyrolysis vapors produced from torrefied biomass under non-catalytic conditions were reduced by 70% in carboxylic acids with respect to vapors originating from crude biomass, but also were richer in ketones and aromatics. In the case of CFP of both crude and torrefied E.globulus on CAG-supported iron and nickel (Fe/CAG and Ni/CAG), the metallic clusters were activated for ketonization, while Ni0 provided additional hydrogenation sites, increasing the production of monoaromatics (c.a.18% selectivity), leading to a high acids-to-ketone (ξA-K = 1.3) and heavy-to-light (ξH-L = 1.0) ratios. Accordingly, Ni/CAG and Fe/CAG were more effective than HZSM-5 –a traditional cracking catalysts– for upgrading CFP vapors to light compounds. The combination of zeolite acid sites with the oxophilic Ni0 and Fe0 allows the deoxygenation of vapors while the ratio of polyaromatics to light aromatics (ξPAHs) was reduced by nearly 50%.