Microenvironment and electronic state modulation of Pd nanoparticles within MOFs for enhancing low-temperature activity towards DCPD hydrogenation  

MOFs中Pd纳米粒子的微环境和电子结构调控增强双环戊二烯低温加氢活性

作　　者：Zhiyuan Liu Changan Wang Ping Yang Wei Wang Hongyi Gao Guoqing An Siqi Liu Juan Chen Tingting Guo Xinmeng Xu Ge Wang 刘志远;王长安;杨平;王薇;高鸿毅;安国庆;刘斯奇;陈娟;郭婷婷;徐鑫梦;王戈(北京科技大学材料科学与工程学院,北京材料基因组工程高精尖创新中心,分子与微结构可控材料技术北京市重点实验室,北京100083;北京科技大学顺德创新学院,广东顺德528399;中石化石油化工科学研究院有限公司,北京100083)

机构地区：[1]Beijing Advanced Innovation Center for Materials Genome Engineering,Beijing Key Laboratory of Function Materials for Molecule&Structure Construction,School of Materials Science and Engineering,University of Science and Technology Beijing,Beijing 100083,China [2]Shunde Innovation School,University of Science and Technology Beijing,Shunde 528399,Guangdong,China [3]Sinopec Research Institute of Petroleum Processing Co.,Ltd,SINOPEC,Beijing 100083,China

出　　处：《Chinese Journal of Catalysis》2024年第9期112-122,共11页催化学报（英文）

基　　金：国家重点研发计划(2021YFB3500700);广东省自然科学基金(2022A1515011918).

摘　　要：Precise control of the local environment and electronic state of the guest is an important method of controlling catalytic activity and reaction pathways.In this paper,guest Pd NPs were introduced into a series of host UiO-67 MOFs with different functional ligands and metal nodes,the microenvironment and local electronic structure of Pd is modulated by introducing bipyridine groups and changing metal nodes(Ce_(6)O_(6) or Zr_(6)O_(6)).The bipyridine groups not only promoted the dispersion Pd NPs,but also facilitated electron transfer between Pd and UiO-67 MOFs through the formation of Pd-N bridges.Compared with Zr6 clusters,the tunability and orbital hybridisation of the 4f electronic structure in the Ce_(6) clusters modulate the electronic structure of Pd through the construction of the Ce-O-Pd interfaces.The optimal catalyst Pd/UiO-67(Ce)-bpy presented excellent low-temperature activity towards dicyclopentadiene hydrogenation with a conversion of>99% and a selectivity of>99%(50℃,10 bar).The results show that the synergy of Ce-O-Pd and Pd-N promotes the formation of active Pd^(δ+),which not only enhances the adsorption of H_(2) and electron-rich C=C bonds,but also contributes to the reduction of proton migration distance and improves proton utilization efficiency.These results provide valuable insights for investigating the regulatory role of the host MOFs,the nature of host-guest interactions,and their correlation with catalytic performance.当今世界能源消费仍以化石能源为主导,导致其副产品供应量大幅增长.目前,C3,C4,C6,C7及C8等馏分都已得到充分利用,然而C5馏分利用率却相对较低.双环戊二烯(DCPD)作为C5馏分的重要组成部分,通过加氢制备四氢双环戊二烯(THDCPD)是合成高能量密度液体燃料的关键步骤.这一过程不仅能带来显著的经济利益和社会效益,还有助于提高资源利用率.本文选取不同金属节点(Zr_(6)O_(6)或Ce_(6)O_(6))与有机配体(含氮基团或不含氮基团)进行组合,制备了一系列UiO-67 MOFs基体(UiO-67(Ce)-bpy,UiO-67(Ce),UiO-67(Zr)-bpy和UiO-67(Zr)),再利用双溶剂法引入了客体Pd NPs,并用于催化DCPD加氢反应.X射线粉末衍射、傅里叶变换红外光谱和透射电镜等结果证明了系列UiO-67 MOFs基体的成功合成,且超小客体Pd NPs均匀地分散在UiO-67(Ce)-bpy,UiO-67(Ce)和UiO-67(Zr)-bpy上.X射线光电子能谱、氢气程序升温还原、拉曼光谱、CO漫反射傅里叶变换红外光谱等结果表明,联吡啶基团和Ce_(6)O_(6)有助于调节Pd的微环境和局部电子结构:(1)联吡啶基团不仅促进了Pd NPs的均匀分散,还通过形成Pd-N桥促进了Pd和UiO-67 MOFs之间的电子转移;(2)与Zr_(6)团簇相比,具有4f电子结构的Ce_(6)团簇中可通过构建Ce-O-Pd界面来调节Pd的电子结构.Pd/UiO-67(Ce)-bpy可在温和条件(50℃,10 bar)下高效催化DCPD加氢反应,DCPD转化率大于99%,THDCPD选择性大于99%.基于系统对比实验和表征结果,推断了Pd/UiO-67(Ce)-bpy的催化机理.该机理中,高活性的Pd^(δ+)物种与超小的Pd^(0)物种紧密结合,这两种活性位点的协同效应促进了对DCPD的高效催化.具体而言,高活性的Pd^(δ+)物种作为Lewis酸位点,能够接受来自富电子DCPD中C=C的π电子,从而形成活化中间体;同时,高度分散的超小Pd^(0)物种具有较强的H_2裂解能力,有助于产生大量的Pd-H.与传统的单金属中心位点相比,由于Pd^(δ+)和Pd^(0)紧密结合,Pd-H�

关 键 词：Interface regulation Pd^(δ+) MICROENVIRONMENT Electronic state HYDROGENATION 

分 类 号：TB383.1[一般工业技术—材料科学与工程] O621.251[理学—有机化学]