Activated carbon aerogel (ACA) bearing sulfonic acid group (ACA-SO3H) was prepared by a sulfonation of activated carbon aerogel, and subsequently, Cs2.5H0.5PW12O40 was impregnated on ACA-SO3H to form XCs2.5H0.5PW12O40/ACA-SO3H with a variation of Cs2.5H0.5PW12O40 content (X=10, 15, 20, 25, and 30 wt%). Palladium catalysts were then supported on XCs2.5H0.5PW12O40/ACA-SO3H by an incipient wetness impregnation method. The prepared Pd/XCs2.5H0.5PW12O40/ACA-SO3H catalysts were applied to the decomposition of 4-phenoxyphenol. 4-Phenoxyphenol was used as a lignin model compound for representing 4-O-5 linkage of lignin. Cyclohexanol, benzene, and phenol were mainly produced by the decomposition of 4-phenoxyphenol. Acidity of Pd/XCs2.5H0.5PW12O40/ACA-SO3H catalysts played an important role in the decomposition of 4-phenoxyphenol. Conversion of 4-phenoxyphenol and total yield for main products (cyclohexanol, benzene, and phenol) increased with increasing acidity of Pd/XCs2.5H0.5PW12O40/ACA-SO3H. Among the catalysts tested, Pd/15Cs(2.3)H(0.5)PW(12)O(40)/ACA-SO3H with the largest acidity showed the highest conversion of 4-phenoxyphenol and total yield for main products. Conversion of 4-phenoxyphenol and total yield for main products over Pd/15Cs(2.5)H(0.5)PW(12)O(40)/ACA-SO3H were much higher than those over palladium catalyst supported on activated carbon aerogel (Pd/ACA) and palladium catalyst supported on activated carbon aerogel bearing sulfonic acid group (Pd/ACA-SO3H). Furthermore, Pd/15Cs(2.5)H(0.5)PW(12)O(40)/ACA-SO3H catalyst was stable and reusable in the decomposition of 4-phenoxyphenol. (C) 2013 Elsevier B.V. All rights reserved.