钾修饰镁铝复合金属氧化物脱除二氧化碳实验研究

Study on CO_2 Capture Performance by Potassium-Promoted MgAl-Hydrotalcite Adsorbent

镁铝复合金属氧化物作为中温（250～450℃）条件下吸收增强水气变换反应的吸收剂具有较好潜力。文中通过碳酸钾浸渍增加吸收剂表面碱性以提高镁铝复合金属氧化物CO_2吸收能力。热重分析研究了煅烧温度、碳酸钾修饰量、反应温度等对其CO_2吸收能力的影响规律,结合吸收剂表征结果,得出中温下吸收剂最佳煅烧温度为400℃左右,最佳碳酸钾修饰含量为25%。利用钾修饰镁铝复合金属氧化物恒温多循环吸收解吸实验及傅里叶变换红外光谱实验结果,推测镁铝复合金属氧化物吸收剂CO_2吸收机理。研究发现钾修饰镁铝复合金属氧化物对CO_2的吸收是部分可逆的,仅通过改变CO_2分压即可完成吸收剂的部分再生。

Mg Al-hydrotalcite adsorbent has received great attention due to its sufficiently high carbon dioxide adsorption capacity at elevated temperatures（250~450 ℃） during the water-gas shift process. In this study, Mg Al-hydrotalcite was impregnated with K_2CO_3 to increase the alkalinity of adsorbent, aiming at enhancing CO_2 sorption uptake. Thermogravimetric analysis was used to investigate the effect of calcination temperature, K_2CO_3 amount and adsorption temperature on the equilibrium CO_2 sorption uptake. Coupled with the help of X-ray diffractometry and N2 gas physisorption analysis, the results showed that the optimal calcination temperature for a maximum equilibrium CO_2 sorption uptake was 400 ℃ and the optimal ratio of K2CO3 in the samples was 0.25： 1 by weight. Moreover, repeated adsorption/desorption cycles experiments by potassium-promoted Mg Al-hydrotalcite adsorbent were conducted and the Fourier transform infrared spectroscopy（FTIR） analysis was applying to further investigate the mechanism of CO_2 sorption enhancement on K_2CO_3-promoted hydrotalcite. The results showed that adsorption of CO_2 for Mg Al-hydrotalcite adsorbents was reversible and regeneration of adsorbents can be realize by altering CO_2 partial pressure.