Catalytic decomposition of 4-phenoxyphenol over Pd/XCs2.5H0.5PW12O40/ACA (activated carbon aerogel)-SO3H (X = 10–30 wt%) catalysts

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/15Cs2.5H0.5PW12O40/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/15Cs2.5H0.5PW12O40/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/15Cs2.5H0.5PW12O40/ACA-SO3H catalyst was stable and reusable in the decomposition of 4-phenoxyphenol.

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► Pd/XCs2.5H0.5PW12O40/ACA-SO3H (X = 10–30 wt%) catalysts were prepared.
► Catalytic decomposition of 4-phenoxyphenol was conducted.
► Acidity of the catalysts played an important role in the reaction.
► Total yield for main products increased with increasing acidity of the catalysts.