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 °C, 5 min of regeneration in pure N₂ at 750 °C), the Na,K-codoped Li₄SiO₄ presented a stable CO₂ capture capacity of 0.22 g_CO2/g_sorbent after the first 10 cycles.

Li ₄ SiO ₄被认为是从化石燃料发电厂的烟道气中捕获CO ₂最具潜力的高温吸附剂材料之一。但是，它通常在低CO ₂浓度下动力学缓慢。在这项工作中，通过柠檬酸溶胶-凝胶法制备了一系列Na / Si（或K / Si）原子比为0.05、0.1和0.2的Na和K掺杂的Li ₄ SiO ₄基吸附剂。所制备的材料通过各种技术进行表征，表明在Li ₄ SiO的表面上存在Li ₃ NaSiO ₄（用于掺杂Na的吸附剂）和LiKCO ₃（用于掺杂K的吸附剂）。_4个粒子。与不含杂原子的Li ₄ SiO ₄相比，所有Na和K掺杂的Li ₄ SiO ₄均表现出大大提高的CO ₂吸附率和在15％CO _2中的容量，尤其是Na掺杂的吸附剂具有最快的吸附速率。 。K掺杂的Li ₄ SiO _4的性能改善是由于在CO ₂吸附过程中形成了共晶的Li ₂ CO ₃ -K ₂ CO ₃熔融碳酸盐，而对于Na掺杂的Li ₄ SiO ₄，Li ₃ NaSiO均被碳化。_{如图4所示}，共晶Li ₂ CO ₃ -Na ₂ CO ₃熔融盐的存在有助于改善。另外，Na和K掺杂的Li ₄ SiO ₄在循环操作中均表现出不完全再生，但后者具有更好的稳定性。在此背景下，我们特意制备了Na ：K：Si：0.1：0.1：1的Na，K掺杂的Li ₄ SiO ₄基吸附剂，该吸附剂显示出快速的动力学和良好的循环稳定性。在30个连续的吸附-再生循环中（在650°C的15％CO ₂中吸附10分钟，在750°C的纯N ₂中再生5分钟），掺有Na，K的Li ₄在前10个循环后，SiO ₄的稳定CO ₂捕集能力为0.22 g _CO2 / g_吸附剂。