Catalyst Design Strategies for Ammonia Synthesis from Nitric Oxide

Abstract

Ammonia synthesis from nitrogen oxides (NO_x) offers a promising alternative to conventional N₂–H₂ processes by bypassing the energy challenge of N≡N bond cleavage while simultaneously processing major air pollutants. This review outlines our recent progress in the NO_x-To-Ammonia (NTA) reaction using CO or H₂ as a reductant. Catalysts based on Pt/TiO₂, Cu/CeO₂, and Ni/CeO₂ revealed distinct mechanistic pathways involving formate and isocyanate (NCO) intermediates rather than direct NO reduction. Optimization of the TiO₂ crystalline phase and preparation improved Pt dispersion and boosted activity. Cu/CeO₂ achieved good low-temperature performance without requiring precious metals. Ni/CeO₂ and bimetallic Ni–Pt/TiO₂ catalyzed an NCO-mediated route. Moreover, partially reduced Pt/TiO_2–δ nearly eliminated N₂O byproducts. These advances demonstrate that rational catalyst design targeting key intermediates enables selective low-temperature ammonia synthesis from NO_x, so promoting a sustainable strategy for energy-efficient nitrogen utilization.