Catalytic hydroprocessing of yellow dodolla oil using thermally stable and mesoporous AlPO4-18 supported β-Mo2C, Ni3C, and WC nanoparticles to produce bio-jet fuel
Authors: Redda Zinnabu Tassew , Kadow Steffen , Barz Mirko , Yimam Abubeker , Wesenfeld Hartmut , Brennecke Daniel , Laß-Seyoum Asnakech 
Published: December 2024

Abstract
Background
The transition from fossil-derived jet fuels to sustainable aviation fuels represents one of the most viable strategies to decarbonize air transport and mitigate CO2 emissions generated by fossil fuel combustion. In the present investigation, a catalytic hydroprocessing upgrading approach was used to transform Yellow Dodolla oil—one of the most prominent inedible Brassica carinata vegetable oils (indigenous to Ethiopia)—into bio-jet fuel.

Methods
The feedstock was upgraded to jet fuel through catalytic hydroprocessing under elevated hydrogen pressure (21 bar), varying temperatures (300 and 500 °C), and employing supported carbon-coated mesoporous and crystalline nanocatalysts (β-Mo2C/AlPO4-18, Ni3C/AlPO4-18, and WC/AlPO4-18) in a laboratory-scale continuous three-phase fixed-bed reactor system. Other variables, such as the volumetric flow rate of oil feedstock, volumetric flow rate of hydrogen gas, hydrogen gas-to-oil ratio, catalyst-to-oil ratio, liquid hourly space velocity, weight hourly space velocity, and residence time, were maintained constant throughout the experimental procedure. Subsequent to an in-depth evaluation of catalytic performance parameters (conversion, selectivity, yield, and deoxygenation rate), a detailed characterization of the liquid phase products was undertaken to explore their most significant properties.

Results
The analysis results demonstrated that the catalytic hydroconversion of the feedstock resulted in a conversion range of 71.57–79.76 wt.%, with the highest conversion of 79.76 wt.% achieved by Ni3C/AlPO4–18 at the maximum temperature. Moreover, the rate of deoxygenation varied from 8.08 to 11.67 wt.% at 300 °C, with nickel catalyst reaching the maximum rate, while it sharply rose to vary from 57.31 to 96.67 wt.% using molybdenum as the temperature increased to 500 °C. It was also discovered that in comparison to bio-gasoline (2.63–8.72 wt.%) and biodiesel (1.18–4.58 wt.%), bio-jet fuel (C8–C16) had noticeably higher yields (23.34–27.31 wt.%), selectivity (37–45 wt.%), and a superb hydrocarbon product distribution (C9–C16) at the maximum temperature, with WC/AlPO4-18 producing the highest yields and selectivity of jet fuel. The characterization results revealed that the hydrocracked liquid products possessed virtually identical physicochemical properties, chemical compositions, hydrogen-to-carbon atomic ratios (1.90–1.92), oxygen-to-carbon atomic ratios (0.002–0.030), and gravimetric energy densities (41.35–42.89 MJ kg−1) to those of conventional jet fuels.

Conclusions
The conclusions of the study demonstrated that the non-food Yellow Dodolla oil was successfully hydrocracked into sustainable aviation fuel using AlPO4-18 supported metal carbide catalyst nanoparticles under the right reaction conditions and reactor system, potentially supporting the significant efforts of the aviation industry to lower its carbon footprint.