Catalytic decomposition of phenethyl phenyl ether and benzyl phenyl ether to aromatics over Pd/CsxH3.0−xPW12O40 (x = 2.0, 2.3, 2.5, 2.8, and 3.0)

Palladium catalysts supported on cesium-exchanged heteropolyacid (Pd/CsxH3.0−xPW12O40, x = 2.0–3.0) were prepared and applied to the decomposition of lignin model compounds. Phenethyl phenyl ether and benzyl phenyl ether were employed as lignin model compounds for representing β-O-4 and α-O-4 bonds in lignin, respectively. Phenol, ethylbenzene, benzene, and toluene were mainly produced by the decomposition of phenethyl phenyl ether. On the other hand, phenol, benzene, and toluene were mainly produced by the decomposition of benzyl phenyl ether. Conversion of lignin model compounds (phenethyl phenyl ether and benzyl phenyl ether) and total yield for main products were closely related to the surface acidity of CsxH3.0−xPW12O40. Conversion of lignin model compounds and total yield for main products increased with increasing surface acidity of CsxH3.0−xPW12O40. Among the catalysts tested, Pd/Cs2.5H0.5PW12O40 with the largest surface acidity of Cs2.5H0.5PW12O40 showed the highest conversion of lignin model compounds and total yield for main products.