Effects of Cerium and Aluminum in Cerium-Containing Hierarchical HZSM-5 Catalysts for Biomass Upgrading

We report the synthesis of multifunctional, hierarchical, cerium-containing HZSM-5 catalysts with various aluminum and cerium contents using a dry-gel, dual templating method. The catalysts were characterized by X-ray diffraction, N₂ physisorption, scanning electron microscopy, diffuse reflectance UV?CVisible spectroscopy, diffuse reflectance Fourier transform infrared spectroscopy, Fourier transform Raman spectroscopy, NH₃ temperature programmed desorption and X-ray photoelectron spectroscopy. At low theoretical Si:Al ratios (15 and 20), the formation of amorphous silica?Calumina materials was observed. However, at higher theoretical Si:Al ratios (30, 40, and 50), crystalline materials were formed. Furthermore, with Si:Al ratios of 50, cerium incorporation as high as 2.2?wt% was obtained using this procedure. To understand the role of aluminum and cerium in the catalyst, the crystalline materials were studied in the catalytic fast pyrolysis of glucose at 600?°C. The catalysts with cerium incorporated showed an increase in the production of oxygenated chemicals as well as CO, compared with their non-cerium containing analogs.