Synergistic promotions between high purity H2 production and CO2 capture via sorption enhanced chemical looping reforming
Mingkai Liu, Yang Li, Xuyun Wang, Zhongrui Gai, Qiong Rao, Tianlong Yang, Jinrui Zhang, Sanli Tang, Ying Pan, Hongguang Jin
Abstract
Hydrogen energy, a promising clean source, holds potential to combat global warming. To achieve efficient and low-carbon H2 production, we proposed an isothermal sorption-enhanced chemical looping reforming (SE-CLR) process to realize the high-purity hydrogen production and in-situ CO2 capture at mild temperatures (550–650 °C). For practical application, the process is characterized to use Fe-Ni double metal oxide particles as steam methane reforming oxygen carriers, and K2CO3-promoted Li4SiO4 particles as CO2 sorbent. The oxygen transfer capacity of metal oxide matintained high at 57.4%, and the K-Li4SiO4 absorbents remained at 22.5% CO2 absorption capacity over 200 isothermal absorption-regeneration cycles. Conducting a synergistic conversion mechanism within double metal oxides and absorbents, and adjusting the absorbent-to-metal oxide mass ratio to 7:4, enhanced hydrogen purity to 92% and CO2 uptake to 95%. Furthermore, in-situ CO2 removal in CLR processes achieved methane conversion and H2 production rates equivalent to conventional CLR processes under the same reaction conditions, but at temperatures ∼60 °C lower. The effects of the reaction temperature, pressure, steam-to-methane and methane-to-solid ratios on SE-CLR performance were studied systematically. Finally, stable hydrogen production with a purity of 91%–89% and CO2 uptake of 94%–91% were obtained over 25 CLR cycles, with minimal changes in mechanical strength of particles.