Yongliang Yan, Matteo Fella, Wenting Hu, Ian S. Metcalfe
Hydrogen is a critical feedstock for numerous industrial processes as well as a clean energy carrier to help decarbonise hard-to-abate sectors, particularly when produced via low-carbon pathways. Low-carbon hydrogen production is anticipated to play a pivotal role in the global energy transition. Among emerging technologies, chemical looping offers a promising route for generating high-purity hydrogen with inherent CO 2 separation. In this work, the chemical looping water–gas shift (CL-WGS) reaction has been demonstrated in a sub-pilot scale counter-current packed-bed reactor using a non-stochiometric ABO 3− δ perovskite (La 0.6 Sr 0.4 FeO 3- δ ) as oxygen carriers. This approach enables super-equilibrium conversions for low-carbon hydrogen production and is demonstrated at the kilogram scale under simulated industrial conditions. At a bed temperature of 820 °C, the counter-current CL-WGS process achieved over 90 % conversion of both H 2 O and CO, compared to the 50 % equilibrium-limited conversion of the conventional water–gas shift reaction. These conversions were consistently maintained across 100 cycles in the stability experiment performed in this study. Comparable performance was observed at a reduced operating temperature of 720 °C, with no evidence of carbon deposition during CO feeding. Various syngas compositions have been investigated as reducing feeds and near-complete conversions can also be achieved. Furthermore, different feeding strategies were explored to optimise reactor performance in response to specific product requirements. Notably, eliminating the inert purge step resulted in only a modest reduction in conversion (2.9–7.0 %) while significantly enhancing production rate and offering potential cost savings. These findings highlight the viability of the CL-WGS process as an efficient and scalable route for low-carbon hydrogen production, with strong potential for pilot-scale demonstration and future commercialisation.