Efficient carbon dioxide adsorption properties of cellular structure Li4SiO4 sorbents prepared by additive manufacturing based on polymer-derived ceramics strategy

Li4SiO4 is considered as one of the most promising materials for post-combustion CO2 capture at high temperature due to its inherent merits. To avoid elutriation in practical application, granulating and shaping of Li4SiO4 sorbents are getting extensive attention. However, the cylindrical or spherical pellets prepared by traditional methods are prone to result in severe damping of CO2 capture performance. In this work, the cellular structure Li4SiO4 sorbent was firstly yielded by additive manufacturing based on polymer-derived ceramics strategy. The phase evolution and calcination process were investigated to optimize the microstructure of that sorbents. In addition, three sodium halides were severally doping in Li4SiO4 sorbents to further improve the CO2 uptake, and the enhancement mechanism was studied. Results show that abundant gas channels around the Li4SiO4 grain can be generated by a novel residual carbon controlling calcination. Additionally, the 6 mol% NaF doped cellular structure Li4SiO4 sorbents possessed superior CO2 adsorption capacity: 0.329 gCO2/gsorbent in 70 vol% CO2 and 0.286 gCO2/gsorbent in 15 vol% CO2, as well as ultrafast adsorption rate. Especially, the sorbents still kept a high adsorption capacity of 0.274 gCO2/gsorbent and obtained a more efficient regeneration process after undergoing 15 cycles of adsorption–desorption in a low CO2 concentration flue gas. Hence, the introduction of additive manufacturing and polymer-derived ceramics strategy in fabrication of Li4SiO4 sorbents provides a new approach and promising prospects for the high-temperature CO2 capture.