双金属催化剂Pd-Coy/Al2O3的协同催化性能研究

Study on Synergistic Catalytic Performance of Bimetallic Catalyst Pd-Co_y/Al_2O_3

通过等体积浸渍法制备了单金属Pd/Al_2O_3催化剂和双金属Pd-Coy/Al_2O_3催化剂,并用于催化2-乙基蒽醌加氢反应。利用N2吸脱附、ICP-AES、XRD、CO化学吸附、TEM、EDX、XPS等表征催化剂的比表面、物相结构以及电子结构。加氢结果发现与单金属Pd/Al_2O_3催化剂相比,双金属Pd-Co0.2/Al_2O_3催化剂加氢效率从11.8 g/L提高到13.5 g/L,选择性从87.2%提高到95.2%。从XPS表征结果发现,催化剂掺杂Co后,一部分Pd颗粒将电子转移到氧化的Co上,形成Pd-Coδ+结构。由羰基活化机理可知,Coδ+吸附C=O中氧的孤对电子,活化C=O,使得C=O加氢反应变得更容易,从而Pd-Co催化剂表现出高催化效率。

Pd-Co/Al2O3 and Pd/Al2O3 were prepared by the impregnation method and tested for the catalytic performance in the hydrogenation reaction of 2-ethylanthraquinone.Their texture structure,crystal phase structure and electron structure were characterized by means of N2 adsorption-desorption,ICP-AES,CO absorption,XRD,TEM,EDX and XPS.The results showed that the hydrogenation efficiency and selectivity of Pd-Co0.2/Al2O3 were 13.5 g/L and 95.2%,respectively,larger than 11.8 g/L and 87.2%of Pd/Al2O3,revealing the synergistic effects between Pd and Co.From XPS characterization,it was found that after doping Co,the electrons of some Pd particles was transferred to oxidized Co to form a new structural species Pd-Co^δ+.Co^δ+in the Pd-Co/Al2O3 system may act as the electrophilic sites for the adsorption and activation of C=O of the 2-ethylanthraquinone molecule through the lone electron pair of the oxygen atom,resulting in the enhanced catalytic performance of Pd-Co catalyst for the hydrogenation of C=O.