Facile synthesis of polymer-derived K, Ti co-doped Li4SiO4-based sorbent for efficient and stable post-combustion CO2 capture

Abstract

Li4SiO4-based sorbent has received considerable attention in the past decade due to its attractive intrinsic merits for post-combustion CO2 capture. To meet the practical applications, the development of Li4SiO4-based sorbent with more higher capture performances by an easy preparation route is desired. In this work, a facile and novel polymer-derived ceramic strategy (PDCs) was used to yield the high-performance Li4SiO4-based sorbent. The phase evolution and microstructure development of Li4SiO4 during the polymer-to-ceramic conversion were investigated. The CO2 capture performances of obtained Li4SiO4 sorbent were studied by comparing with other methods. To further improve its capture performances, Ti(EtO)4-K2CO3 were doped in Li4SiO4, and the enhancement mechanism was surveyed. Results indicate that high-purity Li4SiO4 sorbent with high adsorption properties can be prepared by PDCs route at 700 ℃, and it possessed similar synthesis and adsorption kinetics with the Li4SiO4 prepared by sol–gel method. The 5 mol% Ti doping exhibited a dual enhancement of adsorption capacity and cyclic stability for Li4SiO4 sorbent. Especially, due to the positive synergistic effect of the K, Ti co-doping, the obtained K/5TE-PDCs-Li4SiO4 sorbent showed ultra-high adsorption capacity (0.303 gCO2/gsorbent), ultra-fast adsorption rate (0.219 gCO2/(gsorbent·min)) and ultra-stable cycling performance at a low CO2 concentration (15 vol%). These efficient and stable CO2 capture performances prove the huge potential of polymer-derived K, Ti co-doped Li4SiO4-based sorbent for practical industrial applications.