Self-Activation Mechanism Investigations on Large K2CO3-Doped Li4SiO4 Sorbent Particles

详细信息    查看全文

• 作者：Sai Zhang ; Qi Zhang ; Chen Shen ; Yanhui Ni ; Yongqiang Wu ; Qiufang Wu ; Zibin Zhu
• 刊名：Industrial & Engineering Chemistry Research
• 出版年：2015
• 出版时间：July 29, 2015
• 年：2015
• 卷：54
• 期：29
• 页码：7292-7300
• 全文大小：743K
• ISSN：1520-5045

文摘

This work investigated the self-activation behavior of large K₂CO₃-doped Li₄SiO₄ sorbent particles. In this self-activation mechanism, the sorption ability increased as the number of cycles increased. After the sorption鈥揹esorption cycles occurred, the sorption ability of the K₂CO₃-doped Li₄SiO₄ sorbent was remarkably enhanced from approximately 2.0 mmol CO₂/g sorbent to approximately 5.0 mmol CO₂/g sorbent at 565 掳C in 10 vol % CO₂ atmosphere. The fresh and used sorbents were then characterized through N₂ adsorption and SEM methods. Results showed that the average pore size increased from 7 to 32 nm and the surface microstructure changed from dense to porous, because the molten eutectic mixture formed by Li₂CO₃ and Li₂SiO₃ can facilitate CO₂ diffusion. The formed CO₂ diffusion channel can provide more CO₂ accessibility; this channel can also reduce the CO₂ diffusion resistance through the product layer. Therefore, the sorption ability of the sorbent is enhanced. Meanwhile, the effects of the self-activation temperature were also investigated and the results revealed that the optimal self-activation temperature is 615 掳C. Furthermore, under critical conditions, the self-activated sorbent performed more efficiently than the fresh sample. At 450 掳C under 10 vol % CO₂ atmosphere, the sorption capacity of the self-activated sorbent was approximately 20 times higher than that of the fresh sample. Finally, a pore鈥揷ore model was also proposed to illustrate the K₂CO₃-doped Li₄SiO₄ self-activation mechanism.