沉淀法SiO2包覆纳米CaCO3吸附剂性能

以CO₂为沉淀剂，Na₂SiO₃为硅源，制备了SiO₂包覆纳米CaCO₃吸附剂。TEM测试证实纳米CaCO₃表面包覆一层SiO₂膜, 用SEM & EDX 测试5个包硅样品Si含量为0.67%～4.93%。采用TGA考察吸附剂的分解温度及600℃、20% CO₂条件下的吸附性能。结果表明：采用CO₂沉淀法包覆SiO₂后，与未包硅的纳米CaCO₃相比，分解温度降低9～42℃。纳米SiO₂/CaCO₃吸附剂的循环吸附率、吸附容量、吸附速率均随Si含量的减小先增加后降低。Si含量为1.05%的纳米SiO₂/CaCO₃吸附剂显示最佳吸附性能，第1、5次循环吸附容量分别为8.9、6.0 mol·kg^-1，与未包覆SiO2的纳米CaCO₃相比，分别提高11%、50%，同时在第5次循环快反应段吸附速率较纳米CaCO₃提高10%。与纳米CaCO₃相比，包硅后的吸附剂具有较高的吸附容量和循环吸附率，循环稳定性较好。

Properties of SiO2 coated nano SiO2/CaCO3 sorbents by precipitation method

SiO₂ coated nano CaCO₃ sorbents were prepared by using CO₂ as precipitant and Na2SiO3 as silica source.TEM results showed that nano CaCO₃ was coated by SiO₂, and SEM & EDX tested Si content was 0.67%－4.93%.TGA was used to investigate the decomposition temperature and sorption properties under the condition of 600℃, 20% CO₂ of absorbents.Compared with uncoated nano CaCO₃, the decomposition temperature of SiO₂ coated nano CaCO₃ decreased by 9—42℃.With decreasing Si content, the cycle sorption ratio, cycle sorption capacity and sorption rate of SiO₂ coated nano CaCO₃ absorbents increased first but then decreased.The sample containing 1.05% Si had outstanding sorption properties.The 1st and 5th cycles sorption capacities were 8.9 mol·kg^-1 and 6.0 mol·kg^-1, 11% and 50% higher than uncoated nano CaCO₃.The 5th cycle sorption rate of rapid reaction section was improved by 10% compared with uncoated nano CaCO₃.SiO₂ coated nano CaCO₃ possessed higher sorption capacity and cycle sorption ratio, and better cycle stability than uncoated nano CaCO₃.