A high temperature, lithium orthosilicate based solid absorbent for post combustion CO_2 capture

摘要

A lithium orthosilicate (Li_4SiO_4) based solid absorbent supplied by Toshiba Corporation was found to be promising for post combustion CO_2 capture. The absorbent reacts chemically with CO_2 at elevated temperatures and very large capacities can be achieved. The presence of water vapor greatly enhanced CO_2 absorption rates without affecting capacity. Exposure to flue gas containing even low levels of SO_2 resulted in an irreversible reaction with the absorbent and a decrease in CO_2 capacity. Breakthrough experiments indicated capacities as high as 6.7 mmol CO_2/g. The absorbent will likely require a thermal swing process with absorption at 550°C and regeneration at 650°C.