Effect of metal site influenced by metal particle size on the catalytic hydrogenolysis of cornstalk lignin

The property of metal site affects the catalyst activity significantly. Herein, the effect of metal site influenced by metal particle size on lignin hydrogenolysis was explored. Four different preparation methods were employed to obtain Ru/Al 2 O 3 catalysts with different Ru metal particle size. Ru/Al 2 O 3 -IM catalyst with 10.5 nm Ru particle size only had 16.9 wt% yield of aromatic monomer products. While, Ru/Al 2 O 3 –BH catalyst that possessed the metal particle size of 3.6 nm obtained the high monomer yield of 31.7 wt%, with the a low selectivity of methoxy-containing products. Small metal particle size enabled to enhance hydrogen absorption and activation ability, which provided more active hydrogen species and improved lignin hydrogenolysis performance. It can also expose more metal sites to contact with substrates and promote the demethoxylation reaction to achieve more phenols products. The ratio of phenols/guaiacols product kept a good linear relation with Ru particle size. Moreover, Ru/Al 2 O 3 –BH catalyst with a small Ru particle size had a high TOF of 0.57 mol guaiacol mol Ru −1 min −1 , which was much larger than that of the other Ru/Al 2 O 3 catalysts with a large Ru particle size.