Novel Hierarchical Cerium-Incorporated MFI Zeolite Catalysts for the Catalytic Fast Pyrolysis of Lignocellulosic Biomass

We report the synthesis of a new multifunctional mesoporous zeolite catalyst with cerium incorporated within the framework. This catalyst shows a shift in selectivity from typical HZSM-5 products (benzene, toluene, and xylenes) to valuable oxygenated chemicals (furans, ketones, aldehydes) during the catalytic fast pyrolysis of lignocellulosic biomass. The cerium-incorporated hierarchical zeolite was synthesized using a dry-gel method followed by steam-assisted crystallization. The catalyst was characterized by X-ray diffraction (XRD), N2 physisorption, scanning electron microscopy (SEM), scanning transmission electron microscopy (STEM), transmission electron microscopy (TEM), NH3 temperature-programmed desorption (NH3-TPD), diffuse reflectance FT-IR, and diffuse reflectance UV–Visible (UV–Vis) spectroscopy. The multifunctional catalyst was then studied in the catalytic fast pyrolysis of glucose (a carbohydrate model compound) at 600 °C. The new catalyst was compared with a mesoporous HZSM-5 catalyst with incipient wetness incorporated cerium and an ion exchanged commercial HZSM-5 catalyst. These catalysts behaved similarly to the parent materials, but the new catalyst with cerium incorporated into the zeolite framework exhibited selectivities greatly shifted from aromatics to oxygenated chemicals. Furthermore, this catalyst produced less coke (40 wt % or 11 mol % carbon) and increased CO production through decarbonylation reactions. These properties persisted after catalyst regeneration and recycle.