Catalytic ethanolysis of Kraft lignin to small-molecular liquid products over an alumina supported molybdenum nitride catalyst

•An alumina supported molybdenum nitride catalyst for lignin ethanolysis.•The products are alcohols, esters, mono-phenols, benzyl alcohols and arenes.•The preparation and reaction conditions have great influences on the activity.•907 mg/g lignin aliphatics and 282 mg/g lignin aromatics are obtained.•No significant activity loss is observed in three runs.

An alumina supported molybdenum nitride catalyst (Mo2N/Al2O3) is examined for the ethanolysis of Kraft lignin in supercritical ethanol in a batch reactor with an initial nitrogen pressure of 0 MPa (gauge). No char or tar is formed in this process. The Mo loading as well as the nitriding temperature in the catalyst preparation process has a great influence on the activity. The best performance is obtained over 30 wt% Mo2N/Al2O3 catalyst nitrided at 700 °C. The overall yields of sulfur-free small-molecular products achieve the maximum value of 1189 mg/g lignin, with aliphatic compounds accounting for 907 mg/g lignin and aromatic compounds 282 mg/g lignin, respectively. Both the product yields and the molecular distribution are also strongly dependent on the reaction time and temperature. Furthermore, the Mo2N/Al2O3 catalyst exhibits an excellent recycle performance with no significant activity loss after at least three runs. After reaction, the bulk structure of Mo2N/Al2O3 catalyst was well-preserved only with a slight surface oxidation.

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