Enhancing the Chemo-Enzymatic One-Pot Oxidation of Cyclohexane via In Situ H 2 O 2 Production over Supported Pd-Based Catalysts

作者：Joseph Brehm, Richard J. Lewis, Thomas Richards, Tian Qin, David Morgan, Thomas E. Davies, Liwei Chen, Xi Liu, Graham J. Hutchings · 发表于：ACS Catalysis · 年份：2022 · DOI：10.1021/acscatal.2c03051 · 被引用次数：38 · 研究领域：Catalytic Processes in Materials Science、Electrocatalysts for Energy Conversion、Catalysis and Hydrodesulfurization Studies

High Resolution Image Download MS PowerPoint Slide The combination of an evolved unspecific peroxygenase (UPO), from Agrocybe aegerita (PaDa-I variant) and bimetallic Pd-based catalysts, is demonstrated to be highly effective for the one-pot oxidative valorization of cyclohexane to cyclohexanol and cyclohexanone (collectively KA oil), via the in situ formation of H 2 O 2 from the elements. The alloying of Pd with Zn in particular is found to significantly enhance catalytic performance compared to bimetallic PdAu or monometallic Pd analogues. The improved activity of the PdZn/TiO 2 /PaDa-I system is attributed to the facile formation of PdZn alloys and the resulting electronic modification of Pd, which results in an inhibition of competitive chemo-catalyzed H 2 O 2 degradation reactions and the total suppression of the overoxidation of cyclohexanol. By comparison, the large population of Pd-only clusters present in both the PdAu and monometallic Pd catalysts is considered to be responsible for the promotion of further oxidation products and the unselective conversion of H 2 O 2 to H 2 O, which hampers overall process efficiency. Notably, given the susceptibility of the enzyme to deactivation at moderate H 2 O 2 concentrations, the continual supply of low levels of the oxidant via in situ production represents a highly attractive alternative to the continuous addition of preformed H 2 O 2 or co-enzyme-based systems.