| 内容提要: |
Valorization of lignin is a sustainable strategy to afford valuable aromatics and fine chemical products, which depends on the acid-base property and metal activity of the catalyst. Here, we develop a Pd-doped catalyst that the support nano MgO was modified with carbon species via methanol thermal annealing, catalyze the cleavage of β-O-4 lignin-type dimers (and actual lignin) into aromatics. Methanol as a carbon precursor was processed to a mixture carbon species that loaded active metal palladium. The carbon supported Pd on MgO surface changed the acid-base strength and affected the catalytic activity of the C-O bond hydrolysis / hydrogenolysis of lignin. Strong acid facilitates aldehyde decarboxylation to alkyl aromatics while relatively weak acid and strong base were highly selective for stable aromatics (such as 1-methoxy-4-propylbenzene and 1-methoxy-4-(proplenlyl) benzene). Allowing Pd/MgO-C-700 to be successfully applied to pine lignin depolymerization, to give 25.2 wt% of aromatics yield (based lignin mass) at 200℃without external hydrogen pressure，and rather surprisingly, a good selectivity of 2-methoxy-4-(proplenlyl)phenols. The pathways reaction for lignin valorization are hypothesized over Pd/MgO-C catalyst. |