Alkali-oxygen oxidation mechanism for producing benzene carboxylic acids from lignite: Experimental and molecular modelling studies

•Mechanism of alkali-oxygen oxidation from lignite to BCAs is simulated by ReaxFF.•The ReaxFF simulation results well agree with previous experimental results.•Reaction pathway and active sites for the carboxyl group formation are clarified.•Hydroxy radical is the major oxidant for dehydrogenation and oxygenation.•Alkali can promote side chains break and aromatic ring-opening.