Wittreich Gerhard R, Liu Shizhong, Dauenhauer Paul J, Vlachos Dionisios G
Department of Chemical and Biomolecular Engineering, University of Delaware, 150 Academy St., Newark, DE 19716, USA.
RAPID Manufacturing Institute and Delaware Energy Institute (DEI), University of Delaware, 221 Academy Street, Newark, DE 19711, USA.
Sci Adv. 2022 Jan 28;8(4):eabl6576. doi: 10.1126/sciadv.abl6576. Epub 2022 Jan 26.
Ammonia affords dense storage for renewable energy as a fungible liquid fuel, provided it can be efficiently synthesized from hydrogen and nitrogen. In this work, the catalysis of ammonia synthesis was computationally explored beyond the Sabatier limit by dynamically straining a ruthenium crystal (±4%) at the resonant frequencies (10 to 10 Hz) of N surface dissociation and hydrogenation. Density functional theory calculations at different strain conditions indicated that the energies of NH surface intermediates and transition states scale linearly, allowing the description of ammonia synthesis at a continuum of strain conditions. A microkinetic model including multiple sites and surface diffusion between step and Ru(0001) terrace sites of varying ratios for nanoparticles of differing size revealed that dynamic strain yields catalytic ammonia synthesis conversion and turnover frequency comparable to industrial reactors (400°C, 200 atm) but at lower temperature (320°C) and an order of magnitude lower pressure (20 atm).
如果氨能够由氢气和氮气高效合成，那么它作为一种可替代的液体燃料可为可再生能源提供高密度存储。在这项工作中，通过在氮表面解离和氢化的共振频率（10至10赫兹）下动态拉伸钌晶体（±4%），对氨合成的催化作用进行了超出萨巴蒂尔极限的计算探索。不同应变条件下的密度泛函理论计算表明，NH表面中间体和过渡态的能量呈线性缩放，从而能够描述连续应变条件下的氨合成。一个微观动力学模型，该模型包括多个位点以及不同尺寸纳米颗粒中台阶与Ru(0001)平台位点之间具有不同比例的表面扩散，结果表明动态应变产生的催化氨合成转化率和周转频率与工业反应器（400°C，200个大气压）相当，但温度更低（320°C）且压力低一个数量级（20个大气压）。
