Al-doped silica nanospheres supported Ni catalysts for active sites modulating in the reductive depolymerization of technical lignin

Depolymerizing technical lignin into aromatic monomers is a promising route to renewable aromatic precursors for sustainable aviation fuels, yet it is hindered by the low reactivity of condensed C O and C C linkages. In this work, Al-modified silica nanosphere supported Ni catalysts (Ni/Al-SiO 2 ) are developed for selective lignin hydrogenolysis. The optimal Ni/Al 2 -SiO 2 achieves complete β-O-4 bond conversion and fully transforms 2-phenoxy-1-phenylethanol into phenol and ethylbenzene with yields exceeding 99%. In contrast, commercial Ru/C mainly produces ring-saturated products. Ni/Al 2 -SiO 2 also accelerates the hydrogenolysis of the β-1 bond in 1,2-diphenylethane, delivering high aromatic selectivity with no detectable cycloalkanes. For technical lignin, Ni/Al 2 -SiO 2 affords a 23% aromatic-monomer yield, outperforming that of Ru/C (19%), and maintaining consistent performance across various types of technical lignin. The incorporation of Al generates Lewis-acid sites and polar oxygen motifs, which enrich and polarize the substrates. Adjacent Ni 0 sites dissociate H 2 to generate reactive hydrogen, while strengthened interfacial adsorption, reduced key barriers, and promoted hydrogen spillover enable rapid hydrogenative capping of reactive intermediates, suppressing condensation and preserving aromatic selectivity. This work provides a non-noble-metal interface-engineering strategy for reductive depolymerization of technical lignin into aromatic-rich sustainable aviation fuel precursors.