Chemical Engineering Journal, Vol.374, 328-337, 2019
Novel low cost Li4SiO4-based sorbent with naturally occurring wollastonite as Si-source for cyclic CO2 capture
Li4SiO4-based ceramic has been considered as one of the most promising candidates for high-temperature CO2 capture owing to its relatively high sorption capacity and desirable cyclic stability. Si-source is one of the most important factors affecting the cost as well as the CO2 capture performance of Li4SiO4 sorbent. In this work, naturally occurring wollastonite was firstly employed as the Si-source to produce Li4SiO4-based sorbent. The as-prepared sorbent was primarily composed of Li4SiO4 and CaO. It is believed that the enhanced CO2 capture performance was attributed to the effect of CaO as well as the occurrence of Li-Ca interactions (Li4SiO4 + CaO + CO2 <-> Li2CaSiO4 + Li2CO3), which were experimentally verified via in situ XRD test. As a result, the sorbent possesses a relative high capacity of similar to 0.18 g/g at the initial cycles during the cyclic sorption-desorption test. However, its capacity gradually declined owing to the separation and formation of sintered CaO external shell. From the cost analysis, the as-prepared CaO-Li4SiO4 sorbent can effectively decrease the total raw material cost by reducing Li-demand. To sum up, the good comprehensive performance and relative low cost of as-prepared CaO-Li4SiO4 sorbent make it promising for its practical applications in the future.