Preparation of nanocrystalline ZSM-5 and its catalytic performance in fast pyrolysis of cellulose to produce aromatic hydrocarbons

A series of nanocrystalline ZSM-5 zeolites with abundant intercrystalline mesopores was fabricated by a hydrothermal crystallization method without any mesopore template. The ZSM-5 zeolite was characterized by XRD , XRF , N 2 adsorption, NMR, SEM, TEM and NH 3 -TPD and used for the catalytic fast pyrolysis (CFP) of cellulose . The external surface area of the nanocrystalline ZSM-5 zeolite reached 146.6 m 2 /g, larger than the external surface area of conventional ZSM-5 (57.9 m 2 /g). The product yields of the CFP reaction were studied over different Si/Al ratios of nanocrystalline ZSM-5, and the aromatic yield of nanocrystalline ZSM-5 was generally higher than the aromatic yield of conventional ZSM-5. The relationship between the surface area, acid amounts and product yields was established by drawing a linear fitting curve. The results show that both pore structure and acidity have important effects on aromatic yield and coke yield. Aromatics are generated in micropores, and the increase in external surface area caused by reducing the particle size improves the pyrolysis of cellulose to generate bio-oil vapours, which further diffuse into micropores to generate aromatics.