Three-Dimensional Dual-Site Catalysts for Industrial Ammonia Synthesis at Dramatically Decreased Temperatures and Pressures

Industrial ammonia (NH3) production via the Haber-Bosch (H-B) process is a great achievement of the 20th century, but its energy-intensive character renders NH3 production costly. Despite considerable efforts, progress in developing an efficient H-B catalyst that operates under near-ambient conditions has been slow. In this study, we leverage the confinement concept to facilitate low-temperature and low-pressure NH3 synthesis by constructing three-dimensional (3D) dual-site environments. Through first-principles calculations and microkinetic modeling, we demonstrate that the 3D confined dual site on diporphyrins can surpass the limitations imposed by energy-scaling relations, resulting in a significantly increased turnover frequency (TOF) for NH3 production. Notably, the calculated TOF is 2-3 orders of magnitude higher than that of the commercial ruthenium catalyst at the same working conditions, thus enabling a much-milder H-B process, e.g., at a dramatically decreased working pressure of 10 bar at 590 K. We believe that the strategy will pave the way for the development of economically viable alternatives to current industrial processes.