Jeong Kwon Kim

Catalytic Decomposition of Lignin Model Compounds to Aromatics over Acidic Catalysts

Recent progress on the catalytic decomposition of lignin model compounds to aromatics was reported in this review. Cesium-exchanged heteropolyacid catalysts (CsxH3.0−xPW12O40), palladium catalysts supported on cesium-exchanged heteropolyacid (Pd/CsxH3.0−xPW12O40), and palladium catalysts supported on various activated carbon aerogels (ACAs) (Pd/ACA-SO3H (X), Pd/XCs2.5H0.5PW12O40/ACA, Pd/CsxH3.0−xPW12O40/ACA, and Pd/Cs2.5H0.5PW12O40/ACA-SO3H) were prepared, and they were employed for the decomposition of C–O bond in lignin to aromatics. Phenethyl phenyl ether, benzyl phenyl ether, and 4-phenoxyphenol were used as dimeric lignin model compounds representing for β-O-4, α-O-4, and 4-O-5 bonds in lignin, respectively. It was observed that CsxH3.0−xPW12O40 and Pd/CsxH3.0−xPW12O40 were highly active for the decomposition of phenethyl phenyl ether and benzyl phenyl ether to aromatics. However, these catalysts showed very low catalytic performance in the decomposition of 4-phenoxyphenol. Palladium catalysts supported on various ACAs (Pd/ACA-SO3H (X), Pd/XCs2.5H0.5PW12O40/ACA, Pd/CsxH3.0−xPW12O40/ACA, and Pd/XCs2.5H0.5PW12O40/ACA-SO3H) were efficient for the decomposition of 4-phenoxyphenol to aromatics. Acidity of the catalysts played a key role in determining the catalytic performance in the decomposition of 4-phenoxyphenol to aromatics.