Hierarchical HZSM-5 for Catalytic Cracking of Oleic Acid to Biofuels

Solid acid catalyzed cracking of waste oil-derived fatty acids is an attractive route to hydrocarbon fuels. HZSM-5 is an effective acid catalyst for fatty acid cracking; however, its microporous nature is susceptible to rapid deactivation by coking. We report the synthesis and application of hierarchical HZSM-5 (h-HZSM-5) in which silanization of pre-crystallized zeolite seeds is employed to introduce mesoporosity during the aggregation of growing crystallites. The resulting h-HZSM-5 comprises a disordered array of fused 10-20 nm crystallites and mesopores with a mean diameter of 13 nm, which maintain the high surface area and acidity of a conventional HZSM-5. Mesopores increase the yield of diesel range hydrocarbons obtained from oleic acid deoxygenation from similar to 20% to 65%, attributed to improved acid site accessibility within the hierarchical network.

Automated summary

This study presents the synthesis and application of hierarchical HZSM-5 (h-HZSM-5) catalyst with mesoporous structure, which significantly increases the yield of diesel range hydrocarbons obtained from waste oil-derived fatty acid cracking. The introduction of mesopores through silanization treatment of pre-crystallized zeolite seeds improves the accessibility of acid sites within the hierarchical network, leading to enhanced catalytic performance.