Reproducibility of Lithium Silicate Pellets in N₂ Atmosphere

Abstract

A lithium silicate (Li₄SiO₄) absorbent has been developed as a new CO₂ absorbent at high temperatures, which emits CO₂ at temperatures above 993 K in pure CO₂ at 101 kPa. This temperature is approximately 200 K lower than that for well-known CaO. It was used in CH₄ steam reforming experiments and higher CH₄ conversion was observed for a mixture of a catalyst and an Li₄SiO₄ pellet, than for a catalyst alone, at around 873 K. In this study, the emission temperature and reproducibility of an Li₄SiO₄ pellet (5 mm, spherical) in N₂ was examined from the viewpoint of building a high-efficiency H₂ production system, since the CO₂ emission temperature is lower than that in pure CO₂. The pellet completely emitted CO₂ within 1 h at 873 K, and within 0.5 h at 923 K, and showed high reproducibility, exhibiting almost the same absorption property for 5 cycles.