Hydrodeoxygenation of m-cresol over gallium-modified beta zeolite catalysts

Ga-modified H-Beta (Ga/HBEA) zeolites were evaluated and compared to other Ga-containing catalysts supported on SiO2 and ZSM-5 (MFI) for the hydrodeoxygenation of m-cresol, a model compound representative of lignin-derived phenolics. The products include toluene, benzene, xylene, light hydrocarbons, as well as phenol and other oxygenated compounds. The appearance of bicyclic compounds suggests that the formation of a “surface pool” of oxygenated intermediates may play a role in the reaction pathway. The yield of toluene, a desirable deoxygenated product, increases with reaction temperature, space time (W/F), Ga content, and H2 partial pressure and depends on the type of support used (Ga/HBEA > HMFI ≫ Ga/SiO2). The deoxygenation activity of these catalysts seems to depend on the ability of the zeolite to stabilize specific Ga species, for which HBEA is more effective than HMFI and much more than SiO2.