簇-金属氧化物助剂电子相互作用调控的Ru原子簇催化剂用于温和条件下合成氨反应  

Tuning clusters‐metal oxide promoters electronic interaction of Ru‐based catalyst for ammonia synthesis under mild conditions

作　　者：张天华 胡海慧 李嘉欣 高迎龙 李玲玲 张明远 彭渲北 周岩良 倪军[1] 林炳裕[1] 林建新[1] 朱兵 吴冬霜 张林杰[4] 韩丽丽 郑黎荣[5] 王秀云[1] 江莉龙[1] Tianhua Zhang;Haihui Hu;Jiaxin Li;Yinglong Gao;Lingling Li;Mingyuan Zhang;Xuanbei Peng;Yanliang Zhou;Jun Ni;Bingyu Lin;Jianxin Lin;Bing Zhu;Dongshuang Wu;Linjie Zhang;Lili Han;Lirong Zheng;Xiuyun Wang;Lilong Jiang(National Engineering Research Center of Chemical Fertilizer Catalyst,Fuzhou University,Fuzhou 350002,Fujian,China;College of Chemistry,Fuzhou University,Fuzhou 350002,Fujian,China;School of Materials Science&Engineering(MSE)College of Engineering,Nanyang Technological University,Nanyang Avenue,Singapore 639798,Singapore;State Key Laboratory of Structural Chemistry,Fujian Institute of Research on the Structure of Matter,Chinese Academy of Sciences,Fuzhou 350002,Fujian,China;Institute of High Energy Physics,Chinese Academy of Sciences,Beijing 100049,China)

机构地区：[1]福州大学化肥催化剂国家工程研究中心,福建福州350002 [2]福州大学化学学院,福建福州350002 [3]南洋理工大学材料科学与工程学院,新加坡639798 [4]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 [5]中国科学院高能物理研究所,北京100049

出　　处：《Chinese Journal of Catalysis》2024年第5期209-218,共10页催化学报（英文）

基　　金：国家重点研发计划(2021YFB4000400,2022YFA1604101);国家自然科学基金(22222801,22038002,92361303,22108037).

摘　　要：氨是重要的化肥原料,也是颇具潜力的氢能源载体,对于可再生能源的储存、运输和终端利用至关重要.然而,传统Haber-Bosch工艺合成氨的反应条件苛刻,需要高温高压条件,并消耗大量化石能源及排放大量二氧化碳.可再生能源电解水制氢耦合温和合成氨新技术(eHB),不仅能实现可再生能源电力的“消纳和调峰”,而且可进行低成本、跨地域长距离存储运输,并可将“绿氨”与氢能产业相结合.然而,现有的高温高压合成氨催化剂与eHB工艺相不匹配,因此,迫切需要开发温和条件下高效合成氨催化剂技术,以实现可再生能源电力电解制氢体系和合成氨技术互补融合.目前,虽然助剂对于Ru基纳米簇(≥1 nm)合成氨催化剂的影响规律已得到了广泛研究,但它们对于Ru原子簇催化剂的作用机制尚不清楚,需要进一步揭示.本文考察了Ba及Ce助剂对Ru原子簇催化剂的影响规律,并分析了其作用机制.首先,通过简单的浸渍法将Ba和/或Ce物种掺杂到Ru原子簇催化剂(2 wt%Ru ACCs),制得Ba/Ce/2 wt%Ru ACCs催化剂;然后,通过一系列实验考察了这些催化剂的合成氨性能,并利用多种表征手段对其进行了深入分析.合成氨性能测试结果表明,添加Ba和Ce助剂后,2 wt%Ru ACCs催化剂的合成氨速率明显提高,在400℃和1 MPa下,Ba/Ce/2 wt%Ru ACCs催化剂的合成氨反应速率达到56.2 mmolNH_(3) gcat^(-1) h^(-1),是2 wt%Ru ACCs的7.5倍,且催化剂表现出较好的稳定性,在稳定运行140 h后活性未见明显降低.球差校正电子显微镜和X射线吸收精细结构谱结果表明,负载Ba和/或Ce后,Ru以Ru_(3)原子簇形式存在.X射线吸收近边结构谱和X射线光电子能谱结果表明,Ru与Ba及Ce物种之间存在较强的簇-金属氧化物助剂电子相互作用,可促进电子转移到Ru物种,形成富电子状态的Ru,进而促使电子转移到N_(2)的p*反键轨道,提高温和条件下合成氨反应速率.利用25%N_(2)+75%D_(2Ammonia(NH_(3))is an excellent candidate for hydrogen storage and transport.However,producing NH_(3)under mild conditions is a long-term,arduous task.Atomic cluster catalysts(ACCs)have been shown to be effective for catalytic N2-to-NH_(3)conversion,opening the door to the development of efficient catalysts under mild conditions.Still,ACC formation with thermally stable catalytic sites remains a challenge because of their high surface free energy.Herein,we report anchoring Ba and/or Ce onto Ru ACCs(2 wt%Ru atomic clusters supported on N-doped carbon)to form so-called clusters-metal oxide promoters electronic interaction(CMEI)to stabilize the Ru atomic clusters.The resulting Ba/Ce/Ru ACCs significantly boost the NH_(3)synthesis rate to 56.2 mmolNH_(3)gcat^(-1) h^(-1) at 400℃ and 1 MPa,which is 7.5-fold higher than that of Ru ACC.The strengthened CMEI between the Ba/Ce and Ru atomic clusters across the Ba/Ce/Ru ACC enables electron transfer from Ba and/or Ce to Ru atomic clusters.As such,the electron-enriched Ru atom could facilitate electron transfer to N≡N bondπ*orbitals,which would weaken the N≡N bond and drive the eventual conversion of N2 to NH_(3).This study offers insight into the role of CMEI in Ru ACCs and provides an effective approach for designing stable atomic cluster catalysts for NH_(3)synthesis.

关 键 词：原子簇 助剂 N_(2)活化 合成氨 电子相互作用 

分 类 号：TQ116.21[化学工程—无机化工] TQ426