Thermocatalytic Conversion of Fatty Acids and Their Derivatives to Aromatics over MoOx/HZSM-5 via Tandem Deoxygenation-Aromatization

Abstract

Benzene, toluene and xylenes (BTX) serve as critical components in enhancing cold flow properties in high-performance fuels such as jet fuel, preventing fuel gelling and crystallization at low temperatures while maintaining combustion efficiency; however, their production remains largely reliant on conventional crude oil–derived processes. Alternate pathways such as catalytic pyrolysis, methanol-to-aromatics processes, etc. remain underexplored for sustainable synthesis of these aromatic hydrocarbons. This study presents a novel approach for producing aromatic hydrocarbons using MoOx/HZSM-5 catalyst in a continuous fixed-bed reactor. Feedstocks of interest such as oleic acid (OA), linolenic acid (LA), corn distiller’s oil (CDO), and used cooking oil (UCO) were individually co-fed with water through the catalyst bed. A comprehensive design of experiments was employed to systematically elucidate the effect of critical reaction parameters such as temperature (350–375 °C), space time (1–4 h), and Mo(VI) loading on HZSM-5 (0–10 wt%). With no additional H2 requirement for the process, the maximized operating conditions generated a maximum yield of 85% aromatic hydrocarbons in the liquid product obtained. The major platform chemicals produced during the conversion were benzene, toluene, ethylbenzene, and xylenes (BTEX), which were characterized using GC-MS. Further evidence for the extent of deoxygenation of feedstocks and presence of aromatic compounds in the product was supported by IR and 1H-NMR analyses respectively. The catalysts synthesized were characterized using BET, XRD, IR, SEM, NH3 and XPS. This study positions MoOx/HZSM-5 as a promising catalyst enabling the efficient, H2-free production of BTX from renewable fatty acid feedstocks, advancing the development of sustainable routes to produce these platform chemicals.