Production of sustainable aviation fuels by the two-step alkylation and hydrodeoxygenation of biomass pyrolysis oils over metal-acid bifunctional catalysts

Abstract

Biomass pyrolysis oils present a promising feedstock for sustainable aviation fuel (SAF); however, their shortchain length and high oxygen contents led to an impaired fuel quality and energy density. In this study, the hydrodeoxygenation (HDO) of carvacrol, a model alkyl-phenolic compound from alkylated bio-oils, was investigated using non-noble bimetallic Ni-Cu catalysts supported on a two-dimensional ITQ-2 zeolite. Through systematic optimization of the metal/acid ratio, pore architecture (e.g., pore size, and hierarchical structure), and reaction conditions (140-180 degrees C, 10-50 bar H2), the optimal 4Ni-6Cu formulation achieved >90 % conversion with >80 % selectivity in the generation of high-density, oxygen-free, and aviation-fuel grade hydrocarbons. The application of the developed system to alkylated guaiacol and real alkylated bio-oils further demonstrated the robustness of this catalyst in the presence of a realistic feedstock. Moreover, environmental and energy assessments revealed that the optimized process minimized waste generation and energy consumption, highlighting its potential for scalable SAF production. These findings offer critical insights into the design of costeffective non-precious metal catalysts for the efficient upgrading of biomass-derived oxygenates.