Glycerol dehydration over micro- and mesoporous ZSM-5 synthesized from a one-step method

Abstract

In this work, ZSM-5 zeolites with low Si/Al ratios (25, 50 and 75) were synthesized with a one-step synthesis method and used for the gas-phase glycerol dehydration reaction. The catalysts were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR), N2 adsorption-desorption, scanning electron microscopy (SEM), thermogravimetric analyses (TGA) and temperature programmed desorption of ammonia (NH3-TPD). According to the characterization results, crystalline ZSM-5 zeolites with micro- and mesopores were obtained by the one-step synthesis method. Differences in acidity, related to the Si/Al ratios variation, were observed. The zeolite with Si/Al ratio of 25 showed the best performance during 4 h of the glycerol dehydration reaction with the acrolein selectivity remaining around 70%. The fast diffusion of species in the mesopores and high acidity of the synthesized ZSM-5 favored the acrolein formation from the glycerol dehydration.