Redox-mediated reverse water gas shift integrated with ammonia cracking over Ni/La0.75Sr0.25Cr0.5Mn0.5O3−δ

• The “NH 3 -RWGS” process produces N 2 -free CO from CO 2 and NH 3 . • Combines NH 3 cracking and chemical-looping reverse water gas shift reaction (RWGS). • La 0.75 Sr 0.25 Cr 0.5 Mn 0.5 O 3-δ provides redox capability, and Ni catalyst cracks NH 3 . • 10:1 mixture of LSCM and Ni catalyst shows good redox capacity and cracking rates. NH 3 and CO 2 can react to produce syngas (H 2 + CO), which serves as a feedstock for the production of chemicals or synthetic fuels. Combining NH 3 cracking (NH 3 → 0.5N 2 + 1.5H 2 ) and the redox-mediated reverse water gas shift reaction (RWGS, CO 2 + H 2 → CO + H 2 O), we propose the “NH 3 -RWGS” process in a two-reactor system that can produce N 2 -free syngas without requiring a downstream gas separation step. We investigate the role of La 0.75 Sr 0.25 Cr 0.5 Mn 0.5 O 3−δ (LSCM) in the redox-mediated RWGS, combined with a stabilized Ni catalyst to impart NH 3 cracking functionality. The mixture of LSCM and Ni catalyst at a weight ratio of 10:1 increases the NH 3 cracking activity fivefold compared to using only LSCM. Because the reduction of LSCM proceeds through a two-step mechanism that requires the prior cracking of NH 3 , it also substantially increases the redox reactivity of LSCM. The Ni catalyst exhibits undesirable nitrogen uptake at ∼500 °C, and the redox capacity of LSCM with NH 3 and CO 2 decreases with temperature. Therefore, the process is best implemented at ∼600 °C. Under these conditions, the application of the “NH 3 -RWGS” process with mixtures of LSCM and Ni catalyst is promising to produce high-quality, N 2 -free syngas directly from NH 3 and CO 2 .