Decomposition of 4-phenoxyphenol to aromatics over palladium catalyst supported on activated carbon aerogel

Carbon aerogel (CA) was prepared by a sol–gel polymerization of resorcinol and formaldehyde, and a series of activated carbon aerogels (ACA-H3PO4-X, X = 0, 0.5, 1.0, 2.0, and 3.0) were prepared by a chemical activation using different amount of phosphoric acid (X represented weight ratio of H3PO4 with respect to CA). Palladium catalysts were then supported on activated carbon aerogels (Pd/ACA-H3PO4-X, X = 0, 0.5, 1.0, 2.0, and 3.0) 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 average palladium particle size of Pd/ACA-H3PO4-X. Conversion of 4-phenoxyphenol and total yield for main products increased with decreasing average palladium particle size of Pd/ACA-H3PO4-X. Among the catalysts tested, Pd/ACA-H3PO4-1.0 with the smallest average palladium particle size 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/ACA-H3PO4-1.0 were much higher than those over palladium catalyst supported on commercial activated carbon (Pd/AC).

Graphical abstract.Figure optionsDownload full-size imageDownload high-quality image (117 K)Download as PowerPoint slideHighlights► Decomposition of 4-phenoxyphenol to aromatics was carried out. ► Palladium catalyst supported on activated carbon aerogel (Pd/ACA-H3PO4-1.0) was used. ► Palladium catalyst supported on commercial activated carbon (Pd/AC) was also tested. ► Pd/ACA-H3PO4-1.0 showed a better catalytic performance than Pd/AC.