An integrated hydrodeoxygenation–hydroisomerization strategy for biofuel production from cashew nut shell liquid

Abstract

The high production cost stemming from expensive feedstocks poses a major challenge for industrial biofuels. To address this issue, we report an efficient one-pot process for the co-production of renewable diesel and sustainable aviation fuel (SAF) from low-cost cashew nut shell liquid (CNSL) by integrating hydrodeoxygenation (HDO) with hydroisomerization in a single reactor. The HDO of cardanol, the major phenolic component of CNSL, was first investigated. The results highlighted that the optimal catalyst performance requires a precise tuning among metal sites, pore structure and acidity. Subsequently, to enhance the cold flow properties of the HDO intermediates, a series of bifunctional catalysts were engineered by precisely regulating the spatial distribution of Pt nanoparticles on ZSM-22/Al₂O₃ composite supports. Our study demonstrate that maintaining nanoscale proximity between metal and acid sites is crucial for maximizing the selectivity toward branched isomers. Guided by these insights, reaction conditions were optimized, leading to a stable and efficient integrated process. This work provides a fundamental understanding of catalyst design for upgrading phenolic lipids and offers a practical technological route for valorizing CNSL into advanced biofuels.