The transition to sustainable aviation fuel (SAF) requires efficient catalytic technologies to convert oxygenated lipid-derived feedstocks into hydrocarbon fuels that comply with stringent aviation fuel specifications. Motivated by the relatively low cost of nickel (Ni)-based catalysts and their suitability for large-scale commercial applications, a series of Ni-based catalysts supported on a modified beta zeolite (m-beta) were synthesized to investigate the effects of gallium (Ga) incorporation and the addition of a cerium (Ce) promoter on hydroconversion of palm oil-derived biodiesel. Based on catalyst characterization, the incorporation of Ga improved Ni dispersion and reduced Ni particle size, while Ce further modified Ni electronic states, enhanced H2 consumption, and introduced additional Brønsted acid sites through OH-bridging Ce species. Among the studied catalysts under a central condition, the bimetallic 5Ni5Ga/m-beta catalyst exhibited the highest liquid biofuel yield at 75.9 wt %, with 35.1 wt % biojet fuel-range hydrocarbons, and a high iso-/n-alkane ratio (1.14), attributable to its enhanced Ni active sites and alkane dehydrogenation and aromatization. For the effect of reaction parameters, both the reaction temperature and weight hourly space velocity (WHSV) played critical roles in overcoming limitations in oxygen-removal reactions. Although higher reaction temperatures and lower WHSV enhanced the biojet fuel fraction in the resulting liquid biofuels, these conditions should be carefully optimized to minimize undesirable aromatization. The addition of an appropriate Ce loading to the 5Ni5Ga/m-beta catalyst (5Ni5Ga-5Ce/m-beta) could further improve oxygen removal and alter the reaction pathway, thereby increasing iso-alkane selectivity over aromatic and cyclic compounds. A blend of oil between commercial Jet A-1 and the resulting liquid biofuel from 5Ni5Ga-5Ce/m-beta at 90/10 (v/v) had a heating value comparable to that of Jet A-1 (43.0 MJ/kg) and a freezing point of −54.9 °C. These results highlight the potential of NiGaCe/m-beta catalysts as cost-effective systems for producing SAF-compatible hydrocarbons from biodiesel, expanding strategies for sustainable aviation applications.
Ruthaisirirot et al. (Wed,) studied this question.