Development of Hierarchical Pore Structure MFI Zeolites for Biomass Catalytic Fast Pyrolysis

Zeolites are excellent catalysts due to their well-defined pore structure and high acidity. However, the constricted zeolite micropore (ca. 0.5−1 nm) structure often implies molecular transport limitations. The introduction of mesoporosity in zeolites may help reduce these limitations and improve catalyst selectivity to desirable products. In this study mesopores were created in the ZSM-5 zeolites by two top-down methods: a) desilication and b) surfactant mediated method. Desilication created random pore structures within a wide range of pore sizes, while the surfactant mediated method created smaller mesopores with a more narrow range of pore diameters. Additionally, the mesoporous ZSM-5 zeolites were loaded with metals, such as nickel, ruthenium, and palladium. This was accomplished using the wet impregnation technique, which deposits the metal particles onto the surface of the zeolite. The mesoporous ZSM-5 catalysts were tested for the biomass catalytic fast pyrolysis (CFP) of miscanthus. CFP is an attractive process for the sustainable production of commodity chemicals and biofuels. Our mesoporous ZSM-5 zeolites increased the yields to bio-oil and aromatics and decreased the rates of coke formation.