Catalytic decomposition of phenethyl phenyl ether and benzyl phenyl ether to aromatics over Pd/Cs xH 3.0− xPW 12O 40 ( x = 2.0, 2.3, 2.5, 2.8, and 3.0)

Abstract

Palladium catalysts supported on cesium-exchanged heteropolyacid (Pd/Cs x H 3.0− x PW 12O 40, 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 Cs x H 3.0− x PW 12O 40. Conversion of lignin model compounds and total yield for main products increased with increasing surface acidity of Cs x H 3.0− x PW 12O 40. Among the catalysts tested, Pd/Cs 2.5H 0.5PW 12O 40 with the largest surface acidity of Cs 2.5H 0.5PW 12O 40 showed the highest conversion of lignin model compounds and total yield for main products.