Single-atom iron in zeolite Y for highly efficient acetylene semi-hydrogenation

An acetylene impurity of 0.5-3 % is present in ethylene produced from steam cracking, disrupting the polymerisation process by causing harm to the Ziegler-Natta catalyst. Achieving polymer-grade ethylene requires the removal of acetylene through chemoselective hydrogenation to ethylene, preventing over‑hydrogenation to ethane. The current state-of-the-art process employs expensive, scarce Pd nanoparticles with low selectivity. Single-atom catalysts (SACs) enhance selectivity by preferentially desorbing ethylene. Single atoms of earth-abundant iron can improve selectivity and reduce costs. Here, we introduce zeolite Y-supported single-atom iron (Fe 1 @Y) catalyst, prepared through in-situ hydrothermal method, which efficiently catalyses semi‑hydrogenation of acetylene to ethylene. Characterisation techniques confirm absence of Fe nanoparticles and presence of single-atom Fe sites. Fe 1 @Y achieves a remarkable ethylene selectivity of 93 % ± 2 % at full acetylene conversion, following a dissociative mechanism and stable operation for over 600 h. Under industrial conditions with excess ethylene in the feed, ethylene selectivity of 91 % ± 2 % was maintained at full acetylene conversion. The TOF C 2 H 2 → C 2 H 4 of 711 mol C 2 H 2 → C 2 H 4 h − 1 mol Fe − 1 achieved by Fe 1 @Y is ~14 times greater than previously reported zeolite-supported SACs. Changing iron dispersion from nanoparticles to single atoms significantly enhanced catalytic activity and selectivity, a strategy extendable to other moderately active metals and hydrogenation reactions. • Single-atom iron in zeolite (Fe 1 @Y) was prepared via in-situ hydrothermal method. • Fe 1 @Y achieved >90 % C 2 H 4 selectivity at full C 2 H 2 conversion in industrial feed. • A TOF C 2 H 2 → C 2 H 4 of 711 mol C 2 H 2 → C 2 H 4 h − 1 mol Fe − 1 was achieved using Fe 1 @Y. • Fe 1 @Y facilitated dissociative mechanism and was stable for over 600 h. • Dispersion from nanoparticles to atoms enhanced catalytic activity and selectivity.