Mid-temperature chemical looping methane reforming for hydrogen production via iron-based oxygen carrier particles

Abstract

Chemical looping steam methane reforming (CL-SMR) via iron-based oxygen carriers is a promising method for efficient hydrogen production. To overcome challenges such as high reaction temperatures (>850 °C) and scarcity of low-cost, durable oxygen carriers (OCs), we have developed iron-based particles mixed with various ratios of nickel-based particles to achieve remarkable performance in CL-SMR at 600 °C. The mixed particles showed 85.23% methane conversion and 3.47 and 1.01 mL/min/g_OC hydrogen production rates in the reduction and steam oxidation steps, respectively, in the two-step CL-SMR reaction. In the three-step CL-SMR reaction, air oxidation led to full recovery of oxygen carriers, enhancing methane conversion to 93.30% and elevating hydrogen production rate to 1.41 mL/min/g_OC during steam oxidation. Precise control over methane conversion and hydrogen production in the three-step CL-SMR system is achievable by manipulating the mixing ratios of iron-based to nickel-based OC particles. Comprehensive experimental tests were conducted, covering practical aspects like support materials, gas velocity, and steam-to-carbon ratios. The outstanding cyclic stability of OC particles was confirmed over 200 consecutive redox cycles at 600 °C. The mid-temperature iron-based oxygen carrier particles, integrated with chemical looping demonstration project, might provide a powerful approach toward more efficient and scalable hydrogen production.