Zn^(2+)通过电子转移提升CO酯化反应Pd基催化剂性能  

Introduction of Zn^(2+)Promotes the Catalytic Performance of Pd-based Catalyst for CO Esterification Reaction via Electron Transfer

作　　者：刘洵 江辉波 荆凯强 徐忠宁[1] 郭国聪[1] Liu Xun;Jiang Hui-Bo;Jing Kai-Qiang;Xu Zhong-Ning;Guo Guo-Cong(State Key Laboratory of Structural Chemistry,Fujian Institute of Research on the Structure of Matter,Chinese Academy of Sciences,Fuzhou,Fujian 350002;University of Chinese Academy of Sciences,Beijing 100049)

机构地区：[1]中国科学院福建物质结构研究所,结构化学国家重点实验室,福建福州350002 [2]中国科学院大学,北京100049

出　　处：《化学学报》2023年第7期691-696,共6页Acta Chimica Sinica

基　　金：国家重点研发计划项目(2021YFB3801600,2017YFA0700103,2018YFA0704500);中国科学院战略性先导专项课题(XDA29030600);国家自然科学基金(22172171);福建省自然科学基金(2022H0039);中科院洁净能源创新研究院-榆林学院联合基金(2022010)的资助。

摘　　要：煤制乙二醇是现代煤化工中的一个重要技术路线,其中CO酯化反应合成草酸二甲酯(DMO)是关键步骤之一.负载型Pd基催化剂可有效催化该反应,但关于载体效应的研究相对较少.本研究使用二维层状材料CoAl-LDH(layered double hydroxides)作为载体,合成的Pd/CoAl-LDH催化剂在CO酯化制DMO反应中显示出51.5%的CO转化率.进一步在载体中引入Zn^(2+)合成Pd/ZnCoAl-LDH催化剂,其CO转化率提高至61.8%.XPS(X-rayphotoelectron spectroscopy)表征结果表明, Zn^(2+)的引入促进了Pd活性物种与载体ZnCoAl-LDH之间部分电子转移,从而使该催化剂表现出优异的活性.原位红外实验表明,载体中引入Zn^(2+)使得CO吸附峰发生红移,该结果进一步证实了Zn^(2+)的引入增加了Pd活性位点的局域电子密度.本研究通过结构设计增强催化剂载体的Lewis碱性,从而提高催化剂的反应活性,为进一步提升Pd基多相催化剂的性能提供了有益参考.Coal to ethylene glycol is a crucial route in modern coal chemical industry,and the CO esterification reaction,which synthesizes dimethyl oxalate(DMO),is a key step in this process.While supported Pd-based catalysts are effective for this reaction,research on support effect is limited.In this study,we employed a two-dimensional material CoAl-LDH(layered double hydroxides)as a catalytic support to investigate the support effect for the CO esterification reaction.We prepared various LDH supports with different Co/Al molar ratios and loaded Pd metal using the ALD(atomic layer deposition)method.The successful preparation of LDH carriers was confirmed by TEM(transmission electron microscopy),XRD(X-ray diffraction),and Fourier infrared spectroscopy characterizations.The catalysts were evaluated for their catalytic performance in the CO esterification to DMO reaction.Based on the results,the support with a Co/Al molar ratio of 1∶1 was chosen for further study,as it exhibited the highest Lewis basicity in CO_(2)-TPD(temperature programmed desorption)tests.We then prepared the Pd/ZnCoAl-LDH catalyst by doping Zn2+into the selected CoAl-LDH support.Compared to the Pd/CoAl-LDH catalyst,the Pd/ZnCoAl-LDH catalyst exhibited better catalytic activity for the CO esterification to DMO reaction,with the conversion of CO increasing from 51.5%to 61.8%.XPS(X-ray photoelectron spectroscopy)characterization results indicated that the introduction of Zn^(2+)promoted electron transfer between the Pd active species and ZnCoAl-LDH,which is responsible for the higher activity of the Pd/ZnCoAl-LDH catalyst.In situ DRIRS(diffuse reflectance infrared spectroscopy)experiments demonstrated a red-shift in the adsorption peak of CO,which further confirmed the increase in electron density around the Pd active species.In addition,the 100 h stability test results showed that the introduction of Zn2+can also enhance the stability of the catalyst.After 100 h of evaluation,the catalytic activity of Pd/CoAl-LDH catalyst decreased significantly,while t

关 键 词：ZnCoAl-LDH Lewis碱位点 草酸二甲酯 电子转移 

分 类 号：TQ223.162[化学工程—有机化工] TQ426