Sustainable aromatic production from catalytic pyrolysis of lignin mediated by a novel solid Lewis acid catalyst.

• WO x -TiO 2 -Al 2 O 3 exhibits a catalytic capacity comparable to HZSM-5. • The Ti3+ in W-O-Ti bond can act as Lewis acid sites to bind to C-O bonds. • The increase in Lewis acid favors the deoxygenation reaction. • The coupling effect of WO x and Al 2 O 3 promotes the alkylation reactions of aromatics. Lignin catalytic pyrolysis for sustainable aromatic production is a promising approach for reducing the overwhelming dependence on fossil resources while mitigating CO 2 emissions. The key to achieving the efficient catalytic pyrolysis of lignin lies in the rational design of advanced catalysts with excellent deoxygenation capacity. In this study, we develop a novel mixed metal oxide (WO x -TiO 2 -Al 2 O 3) as efficient solid Lewis acid catalysts for the catalytic pyrolysis of lignin. We demonstrate that WO x -TiO 2 -Al 2 O 3 exhibits the best catalytic ability at a pyrolysis temperature of 600 °C with a catalyst-to-lignin weight ratio of 2. The yields of bio-oil and monocyclic aromatic hydrocarbons (benzene, toluene, and xylene) can respectively reach 30.2 wt% and 1.6 wt%, which is slightly lower than those of the commercial HZSM-5 catalyst (31.7 wt% and 1.9 wt%). We also prove that the M−O−M bonds formed between oxygenophilic metals can generate electron holes as the temperature increasing. Those holes may combine with C-O bonds of phenolic compounds to generate metal–oxygen–carbon (M−O−C) bonds, facilitating the deoxygenation of lignin-derived pyrolysis vapours. These findings may provide guidance for the design of novel solid Lewis acid catalysts for the direct deoxygenation of lignin for the preparation of aromatic compounds. [ABSTRACT FROM AUTHOR]