Sorption-Enhanced Methanation Using CaO- and Ni-Based Catalysts as Functional Materials

In this work, a detailed parametric study of sorption-enhanced methanation (SEM) to produce synthetic natural gas was carried out. A commercial Ni-based catalyst and CaO as a H₂O sorbent were used as functional materials. The operational parameters studied included the reaction temperature, H₂/CO module in the feed gas, CO space velocity, and sorbent/catalyst mass ratio. High CH₄ purity, close to 90%, was obtained at 275 °C, utilizing a module with H₂/CO = 3 as the feed gas, 0.8 kg_CO/kg_cat h, and a CaO/catalyst mass ratio of 1. Under these operational conditions, a cycle stability test was performed, demonstrating good reproducibility over 14 cycles. SEM performance was also analyzed using a sintered CaO sorbent. The study demonstrated that the reactivation of the material resulted in similar effectiveness to using calcined CaO. Finally, the process was studied utilizing a H₂/CO/CO₂ mixture as the feed gas, obtaining 80% CH₄ purity in the product gas.