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A comparison between the behavior of Y and ZSM-5 zeolites having the same Si/Al ratio was established in the catalytic cracking of bio-oil for producing fuels and platform chemicals. The catalysts were prepared by agglomerating each zeolite with a mesoporous γ-Al2O3 matrix. Properties of the zeolites and the catalysts were characterized by N2 ads/desorption, SEM-EDX, pyridine-FTIR, tBA-TPD, and NH3-TPD techniques. The experiments were conducted in a continuous two-step catalytic cracking system (TS-CC) at 450 °C. Both catalysts are highly selective to C5-C12 hydrocarbons, with a composition strongly affected by the porous structure and acidity of the zeolite. The HZSM-5 catalyst (high acid strength and Brønsted/Lewis ratio) promotes cracking and deoxygenation reactions that lead to C2−C4 olefins which condensate into aromatics, yielding 9% of 1-ring aromatics (3% BTX) and 4% of naphthalenes for a feed conversion of 85%. These reactions are less favored over the HY catalyst, which promotes olefins oligomerization and hydrogen-transfer reactions, yielding 14% of highly aliphatic gasoline (> 30% linear paraffins) and 5% of C13−C20 diesel fraction (> 90% long chain paraffins). The remaining upgraded bio-oil obtained with both catalysts is composed of light oxygenates, with ketones, acids and esters as main components and low concentration of phenolic compounds.
Valle et al. (Wed,) studied this question.