Production of Light Olefins from Catalytic Cracking Bio-oil Model Compounds over La₂O₃-Modified ZSM-5 Zeolite

Abstract

Diminishing fossil fuel reserves and the increasing consumption of light olefins are driving intensive research to find a new non-petrochemical substitute resource to produce light olefins. Biomass-derived bio-oil is a promising substitute resource because it is renewable, abundant, and carbon-neutral. In this study, three bio-oil models, oleic acid (OA), methyl laurate (ML), and waste cooking oil (WCO), were catalytically cracked over La2O3-modified ZSM-5 (LaZ) aiming for production of light olefins. The content of La2O3 in catalysts was adjusted to optimize the structure and properties of catalysts. The maximal light olefin yield was 131 mL/g for OA, 120 mL/g for ML, and 128 mL/g for WCO, which was obtained over the LaZ catalyst containing 6% La2O3 (6LaZ). The maximal light olefin selectivity was 36.1% for OA, 30.3% for ML, and 33.8% for WCO. The obtained light olefins mainly contained propylene (13.6–17.1%), ethylene (10.7–15.4%), and butene (5.3–6.3%). Aromatic hydrocarbons and graphite were the main components in the liquid product and solid product (coke), respectively. 6LaZ exhibited better catalytic activity and anticoking ability than La-free ZSM-5, which was attributed to its appropriate porosity and acidity. The unsaturated molecular structure of feedstock was found, helping to improve the light olefin yield. Our investigations are useful for developing a new process route to produce light olefins from renewable biomass resources.