Pressurized Chemical Looping–Steam Methane Reforming for Thermal H2 Production

Abstract

Large quantities of heat, steam, electricity, and hydrogen are required in many major industrial sectors such as oil and gas and iron and steel. However, the most common technologies for generating these products are large-scale emitters of CO₂ and at the present time must still rely on fossil fuel feedstocks. The deployment of carbon capture, utilization, and storage (CCUS) technologies will be critical in reaching both Canadian and international net-zero emissions targets by 2050. More traditional approaches for CO₂ capture, such as solvent-based scrubbing, can be implemented to reduce emissions but often fall short of attaining carbon-neutral products. Pressurized chemical looping–steam methane reforming (PCL-SMR) has the potential to produce zero-emission H₂ for combustion systems at an attractive cost, thereby avoiding the need for postcombustion CO₂ capture which can be cost prohibitive at certain scales. This is achieved by replacing the existing SMR firebox with dual-reactor chemical looping with inherent CO₂ separation. This work considers a comparison between conventional SMR with and without postcombustion CO₂ capture to that of PCL-SMR at an industrial-scale H₂ production level (∼290 t/day). In all configurations, the syngas is cooled, the H₂ product is separated via pressure swing adsorption before compression, and the tail gas is recycled into the combustion system. The captured CO₂ is processed via a cooling, drying, and compression system to meet the supercritical CO₂ transportation specifications. By operating at elevated pressures (∼6 bar(g)), zero direct CO₂ emissions are achievable without the need for costly gaseous O₂ production, while increasing the net H₂ production efficiency and lowering fresh-water consumption. A detailed comparative techno-economic analysis and life-cycle assessment show a significantly lower levelized cost of H₂ production via PCL-SMR in comparison to SMR with amine-based CO₂ capture, while achieving both greater direct (Scope 1) and indirect (Scopes 2 and 3) CO₂ emission reductions. In addition, several other key benefits of PCL-SMR beyond costs and environmental burdens are highlighted, such as a significant reduction in reformer tube stress and H₂ production efficiency.