Air-promoted selective hydrogenation of phenol to cyclohexanone at low temperature over Pd-based nanocatalysts

• 来源期刊: 中国科学:化学（英文版）
• 年，卷（期）: 2017,（11）
• 页码范围: 1444-1449
• 页数: 6页
• 语种: 英文
• DOI: 10.1007/s11426-017-9095-4

摘要

Attaining high activity with high selectivity at low temperature is challenging in the selective hydrogenation of phenol to cyclohexanone due to its high activation energy (Ea,55-70 kJ/mol).Here we report a simple and efficient strategy for phenol hydrogenation catalyzed by Pd in aqueous phase at 30 ℃ by introducing air to promote the catalysis.With the assistance of air,＞99％ conversion and ＞99％ selectivity were achieved over Pd(111)/Al2O3 with an overall tumover frequency (TOF) of 621 h 1,～80 times greater than that of the state-of-art Pd catalyst at 30 ℃.Mechanism studies revealed that phenol was activated to generate phenoxyl radicals.The radicals were yielded from the reaction between phenol and hydroxyl radicals in the presence of hydrogen,oxygen and protic solvent on Pd.The phenoxyl pathway resulted in a low apparent Ea (8.2 kJ/mol) and thus high activity.More importantly,this strategy of activating substrate by air can be adapted to other Pd based catalysts,offering a new thinking for the rational design of cyclohexanone production in industry.