# Promotional Effect of Mn On NH3 Synthesis Over Inverse Iron Catalyst

## TL;DR

A new iron-manganese catalyst boosts ammonia production efficiency under mild conditions by enhancing nitrogen activation.

## Contribution

A Mn-incorporated iron catalyst with inverse structure is developed, showing significantly improved ammonia synthesis performance.

## Key findings

- The FeMn catalyst achieves about twice the ammonia formation rate of conventional iron catalysts under mild conditions.
- Mn enrichment at the surface lowers activation energy and enhances N2 activation.
- Surface Mn3N2 species are identified as key to improving nitrogen bond cleavage and ammonia synthesis.

## Abstract

The Haber–Bosch process has been established for over a century, and it still remains central to global ammonia production. To this day, industrial NH3 synthesis still relies on fuzed iron catalysts developed in the early 20th century, which underscores the ongoing challenge in the development of alternative catalysts with superior activity under mild conditions. Here, we report a Mn‐incorporated iron (FeMn) catalyst prepared via a facile sol–gel method. The resultant FeMn catalyst exhibits an approximately twofold higher NH3 formation rate than that for the conventional commercial iron catalyst under mild conditions. Kinetic analysis revealed that Mn incorporation results in ammonia synthesis with a lower apparent activation energy, which suggests enhanced N2 activation. Further structural and surface analyses indicate that Mn enrichment at the catalyst surface favors N2 activation, which likely facilitates N≡N bond cleavage and contributes to the observed activity enhancement. This work highlights a simple yet effective strategy to boost the performance of Fe‐based catalysts for ammonia synthesis under mild conditions.

We report a novel catalyst with an inverse structure of a supported metal catalyst, consisting of mesoscale iron particles doped with Mn species (FeMn). The FeMn catalyst exhibited about twofold higher NH3 formation rate than the conventional commercial iron catalyst under mild conditions. Characterization and kinetic studies revealed that surface Mn3N2 species play a key role in N2 activation, leading to enhanced NH3 synthesis over iron.© 2026 WILEY‐VCH GmbH