文献类型：期刊文献

英文题名：Sol-gel derived, Na/K-doped Li4SiO4-based CO2 sorbents with fast kinetics at high temperature

作者：Cui, Hongjie[1];Li, Xinlei[1];Chen, Hui[1];Gu, Xiongyi[1];Cheng, Zhenmin[1];Zhou, Zhiming[1]

机构：[1]East China Univ Sci & Technol, Sch Chem Engn, Shanghai 200237, Peoples R China

年份：2020

卷号：382

外文期刊名：CHEMICAL ENGINEERING JOURNAL

收录：;EI(收录号：20194107517584);WOS:【SCI-EXPANDED(收录号:WOS:000503381200237)】；

基金：This work was supported by the National Natural Science Foundation of China (21776088) and the Fundamental Research Funds for the Central Universities (222201718003).

语种：英文

外文关键词：High-temperature CO2 sorbent; Li4SiO4; Na- and K-doped; Sorption mechanism; Kinetics

摘要：Li4SiO4 is considered as one of the most potential high-temperature sorbent materials for CO2 capture from the flue gas of fossil fuel-fired power plants. However, it usually suffers from slow kinetics at low CO2 concentrations. In this work, a series of Na- and K-doped Li4SiO4-based sorbents with Na/Si (or K/Si) atomic ratios of 0.05, 0.1 and 0.2 were prepared by a citrate sol-gel method. The prepared materials were characterized by various techniques, which revealed the presence of Li3NaSiO4 (for Na-doped sorbents) and LiKCO3 (for K-doped sorbents) on the surface of Li4SiO4 particles. All Na- and K-doped Li4SiO4 showed greatly enhanced CO2 sorption rates and capacities in 15% CO2 as compared to the heteroatom-free Li4SiO4, and in particular, the Na-doped sorbents had the fastest rates. The improved performance of K-doped Li4SiO4 resulted from the formation of eutectic Li2CO3-K2CO3 molten carbonates during CO2 sorption, while for Na-doped Li4SiO4, both the carbonation of Li3NaSiO4 and the presence of eutectic Li2CO3-Na2CO3 molten salts contributed to the improvement. In addition, both Na- and K-doped Li4SiO4 exhibited incomplete regeneration during cyclic operation, but the latter had better stability. In this context, we deliberately prepared a Na,K-codoped Li4SiO4-based sorbent with a Na:K:Si atomic ratio of 0.1:0.1:1, which showed fast kinetics and good cyclic stability. During 30 consecutive sorption-regeneration cycles (10 min of sorption in 15% CO2 at 650 degrees C, 5 min of regeneration in pure N-2 at 750 degrees C), the Na,K-codoped Li4SiO4 presented a stable CO2 capture capacity of 0.22 g(CO2)/g(sorbent) after the first 10 cycles.