Catalytic decomposition of 4-phenoxyphenol to aromatics over Pd/XCs2.5H0.5PW12O40/ACA (X = 10, 20, 30, 40, and 50 wt%) catalysts

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 4O5 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/20Cs2.5H0.5PW12O40/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/20Cs2.5H0.5PW12O40/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).

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► Pd/XCs2.5H0.5PW12O40/ACA with different Cs2.5H0.5PW12O40 content (X) was prepared.
► Catalytic decomposition of 4-phenoxyphenol to aromatics was conducted.
► Acidity of the catalysts played an important role in the reaction.
► Total yield for aromatics increased with increasing acidity of the catalysts.