Selective cleavage of CO bond in benzyl phenyl ether over Pd/AC at room temperature
Selectively cleaving the C O bonds in lignin to produce aromatic products are challenging problems. Currently, catalytic hydrogenolysis of C O bonds in lignin requires harsh conditions. Herein, selectively cleaving C O bond of benzyl phenyl ether (BPE) was studied over Pd/AC, Ru/AC and Ni/AC. Among these catalysts, Pd/AC efficiently cleaved C O bond in BPE under super mild conditions (25 °C, 2 h and 0.1 MPa H 2 ). The products were toluene and phenol without hydrogenation of the aromatic ring . The main competitive step of hydrogenolysis and hydrogenation is sensitive to reaction temperature over Pd catalyst. A mild temperature is preferred for hydrogenolysis, since the H species nearby the oxygen atom are more strongly adsorbed than nearby the benzene rings . With the different H-donor solvents, the highest conversion of BPE was obtained in isopropanol. Based on the experiments, the reactions occurred via cleavage of the C aliphatic -O bond in BPE and the synergetic effects between the H from absorbed H 2 on the surface of the Pd and the intermediates radicals of benzyl and phenoxy should be the key points to such an optimum result.
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