Biogas, as a renewable gas resource rich in CH4 and CO2, is a hydrogen production feedstock. Compared to conventional steam reforming, sorption‑enhanced steam reforming enables high-purity hydrogen production through inherent CO2 separation while simplifying the process configuration. Based on the Gibbs free energy minimization method, HSC Chemistry was employed to investigate the effects of temperature, pressure, S/C molar ratio, and CaO/C molar ratio on H2 yield, H2 content, and H2 amplification factor, thereby determining the optimal hydrogen production conditions. The results show that temperature has a similar influence on product distribution in both steam reforming and sorption‑enhanced steam reforming of biogas systems. The introduction of CaO shifted the optimal reaction temperature from 650–700°C to 500–600°C, enabling high H2 content and H2 amplification factor at lower temperatures. Increasing the S/C ratio promoted methane conversion and hydrogen production, although the enhancement became limited when S/C exceeded 3. Increasing the CaO/C ratio significantly improved CO2 capture and hydrogen purity, while the improvement gradually leveled off when CaO/C >3. Sorption‑enhanced steam reforming increased H2 content from 67.6% to 99.4% and reduced system enthalpy by approximately 27%–33% relative to conventional steam reforming. Considering hydrogen yield, purity, and thermodynamic efficiency, the optimal operating conditions were determined to be 500–600°C, 1 bar, S/C = 3, and CaO/C = 3. These findings provide thermodynamic guidance for the design and potential industrial application of sorption‑enhanced steam reforming processes for efficient hydrogen production from biogas.
Wang et al. (Mon,) studied this question.