Ni-Substituted LaFeO ₃ Perovskite Catalysts for Enhanced Ammonia Production via Microalgae Gasification

Ammonia (NH3) is increasingly recognized as a promising sustainable energy carrier. Ammonia production through the gasification of nitrogen-rich biomass offers a sustainable, decentralized, and flexible approach for the efficient storage and conversion of renewable energy. In this work, LaFe1–xNixO3 (x = 0–0.3) perovskite catalysts were employed to enhance the ammonia yield from microalgae gasification. The effects of Ni substitution on catalyst structure, catalytic performance, and nitrogen conversion pathways were systematically investigated. Characterization results reveal that Ni incorporation decreases lattice parameters, enhances oxygen vacancy concentration, and increases adsorbed oxygen, thereby improving catalytic performance. Gasification experiments demonstrate that Ni doping significantly enhances syngas generation and fuel-N conversion efficiency. The conversion of fuel-N into NH3 increases from 56.4% for LaFeO3 to 62.9% for LaFe0.7Ni0.3O3, accompanied by reduced HCN formation and higher NH3/HCN ratios, indicating improved NH3 selectivity. LaFe0.7Ni0.3O3 catalyst exhibits excellent structural stability and coke resistance after 20 consecutive cycles. These results demonstrate that Ni-substituted LaFeO3 perovskites enable efficient and durable green ammonia synthesis from nitrogen-rich biomass under mild conditions.