リチウムシリケートペレットを充填した反応器による高温CO_2除去

概要

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For the purpose of carbon dioxide (CO_2) capture at high temperatures, Toshiba developed a novel CO_2 absorbent, a lithium silicate (Li_4SiO_4). It shows an immediate CO_2 absorption and emission properties, which results in an obvious weight change of up to 36%. Since, in the case of Li_4SiO_4, CO_2 emission occurs at a considerably lower temperature than for a calcium oxide (CaO) absorbent, the reaction between Li_4SiO_4 and CO_2 is very reversible. The emission temperature in 101kPa of pure CO_2 is ca. 800℃, whereas CaO absorbent requires a temperature of 950℃. Considering the practical use of this material as a CO_2 absorbent for power plants, a pellet-type absorbent is thought to be more realistic than a powder-type absorbent. Moreover, regarding the application to the system, the characterization of a reactor using Li_4SiO_4 pellets is required. This paper describes the removal efficiencies of a packed bed reactor using cylindrical pellets of Li_4SiO_4. In a gas flowing condition of 20vol% CO_2, the reactor achieved 100% CO_2 removal at 500℃. Temperature dependence was also investigated. It is noteworthy that the reactor and gas stream were obviously heated during the CO_2 removal because of the exothermic reaction between the Li_4SiO_4 and CO_2. We believe that this phenomenon is one of the important findings to improve the energy penalty for CO_2 recovery.
社団法人日本セラミックス協会の論文
2006-09-01