Catalytic upgrading of wet waste-derived carboxylic acids to sustainable aviation fuel and chemical feedstocks†

Abstract

We develop a catalytic process comprising exclusively of flow reactions for conversion of wet waste-derived volatile fatty acids to sustainable aviation fuel (SAF) and key aromatic building blocks (benzene, toluene, ethylbenzene, and xylene; BTEX). Acids are upgraded via sequential ketonization and either cyclization of light (C_3–7) ketones to BTEX and an aromatic SAF blendstock or hydrodeoxygenation of C₈₊ ketones to an alkane SAF blendstock. The enabling step investigated in this work is light ketone cyclization over H/ZSM-5, which was chosen through screening upgrading of 4-heptanone over solid acidic and basic catalysts. We then determined the reaction network of 4-heptanone upgrading by analyzing selectivity trends with conversion and concluded that the reaction should be run at full conversion. Finally, we demonstrated the entire acid upgrading process by converting commercial food waste-derived carboxylic acids to SAF blendstocks and BTEX. We blended the C₉₊ aromatic and alkane products to create one SAF blendstock and show that this mixture can be blended 50/50 with Jet A and meet all critical property standards. Techno-economic analysis and life cycle assessment show that utilizing a food waste feedstock for the process can be economically feasible with current policy incentives and reduce greenhouse gas emissions by more than 250%.