Biotemplated synthesis of highly stable calcium-based sorbents for CO₂ capture via a precipitation method

详细信息    查看全文

• 作者：Thongthai Witoon ; Thumrongrut Mungcharoen ; Jumras Limtrakul
• 关键词：Carbon dioxide ; Calcium oxide ; N2-porosimetry ; Carbonation/calcination ; Chitosan
• 刊名：Applied Energy
• 出版年：1 April, 2014
• 年：2014
• 卷：118
• 期：Complete
• 页码：32-40
• 全文大小：2335 K

文摘

The alternation between uptake and release of CO₂ by CaO sorbents is a promising method for removal of CO₂ from a hot gas stream. The main drawback of this method is the deterioration of CO₂ capture capacity following multiples cycles. In the present study, CaO sorbents with a high CO₂ capture capacity and improved stability were prepared using chitosan as biotemplate via a simple precipitation method. Effects of mass ratio of chitosan to Ca²⁺ (0.125:1-2.5:1) on physical properties of the CaO sorbents as well as their CO₂ capture performance were investigated. The cyclic CO₂ capture performance of the CaO sorbents derived from chitosan template has been compared with that of CaO templated on a synthetic polymer (SDS), a hybrid of chitosan and SDS, and a non-templated CaO sorbent. The variation of chitosan to Ca²⁺ ratios was found to drastically change both the morphology and size of the CaCO₃ products. CaCO₃ particles homogeneously amalgamated with the chitosan matrix at a ratio of chitosan to Ca²⁺ of 0.125:1-0.75:1. With a yet higher ratio of 0.75:1, larger amount of chitosan molecule could incorporate into the CaCO₃ particles, but a phase separation was also observed. SDS was found to act as a template for the formation of large CaCO₃ particles with a spherical shape. CO₂ uptake activity and stability were found to depend on both surface area and shape of the synthetic CaO materials. The CaO sorbent derived from chitosan template exhibited a higher CO₂ uptake activity and stability than the other CaO sorbents. The CaO prepared in the presence of chitosan to Ca²⁺ ratio of 0.75:1 achieved the highest CO₂ uptake of 83.75% in the first cycle and retained an excellent carbonation conversion of 57.78% after 20 consecutive test cycles. This finding indicates that the CaO derived from chitosan template constitutes a feasible option as a CO₂ sorbent due to its potentially low costs, environmentally benign nature, and elevated CO₂ capture capacity.