Activated carbon aerogel (ACA) was prepared by a chemical activation of carbon aerogel using phosphoric acid (H3PO4). A series of Cs2.5H0.5PW12O40-impregnated activated carbon aerogels (XCs2.5H0.5PW12O40/ACA) were prepared with a variation of Cs2.5H0.5PW12O40 content (X) in order to provide acid sites to ACA. Palladium catalysts were then supported on Cs2.5H0.5PW12O40-impregnated activated carbon aerogel (Pd/XCs2.5H0.5PW12O40/ACA, X = 10,20, 30, 40, and 50 wt%) by an incipient wetness impregnation method for use in the decomposition of 4-phenoxyphenol to aromatics. 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. Conversion of 4-phenoxyphenol and total yield for main products (cyclohexanol, benzene, and phenol) were closely related to the acidity of Pd/XCs2.5H0.5PW12O40/ACA. Conversion of 4-phenoxyphenol and total yield for main products increased with increasing acidity of Pd/XCs2.5H0.5PW12O40/ACA. Among the catalysts tested, Pd/20Cs(2.5)H(0.5)PW(12)O(40)/ACA 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/20Cs(2.5)H(0.5)PW(12)O(40)/ACA were much higher than those over palladium catalyst supported on commercial activated carbon (Pd/AC) and palladium catalyst supported on activated carbon aerogel (Pd/ACA). (C) 2012 Elsevier B.V. All rights reserved.