掺杂镧铝盐对钙基循环捕捉CO_2能力的影响

Effect of Doped Lanthanum and Aluminum Salts on Calcium Looping Cycle for CO_2 Capture

钙基循环已经被证明是燃煤电厂尾气CO2捕捉最有吸引力的方式之一。但是,随着循环反应次数的增加,再生的CaO的捕捉效率迅速降低。为提高多次循环后CaO的碳化效率和吸收容积,采用燃烧合成法制备不同掺杂质量比例的改性CaO/La2O3、CaO/Ca12Al14O33、CaO/LaAlO3吸收剂。研究结果表明,不同量地掺杂镧盐或铝盐均能大幅提高钙基CO2吸收剂的碳化效率,其中单独掺杂铝盐较镧盐使CaO循环捕捉CO2的效果更好。但是同时掺杂2者时,生成的LaAlO3作为极具活性的催化物质,只需要较小的掺杂量(5%),就可以使吸收剂在15个碳化/煅烧循环后仍然获得超过0.4(gCO2/g吸收剂)的吸收容积。而单独掺杂铝盐,所生成的Ca12Al14O33作为一种惰性骨架物质,只有在掺杂量较大(>10%)时才能使吸收剂获得等量的吸收容积。

Calcium looping cycle has been identified to be an attractive method for CO2 capture from flue gas of coal combustion.However,it is well known that the absorption capacity of CaO sharply decreases with increasing carbonation/calcination cycles.In order to improve the carbonation conversion and absorption capacity of CaO after mutiple cycles,modified CaO/La2O3,CaO/Ca12Al14O33 and CaO/LaAlO3 sorbents were synthesized at the different doped weight ratios by combustion-synthesis method.The experimental results indicated that all different doped weight ratios of lanthanum or aluminum salts played an active role in improving carbonation conversion of CaO-based CO2 sorbents and aluminum salt had better effect than lanthanum salt when only one of them was doped.However,when both of them were doped simultaneously,the formed LaAlO3,a high active catalyst,needed only a low doped weight ratio（5%） to make the sorbent achieve high absorption capacity of over 0.4（g CO2/g sorbnet） after 15 carbonation/calcination cycles.By contrast,when only the aluminum salt was doped,the formed Ca12Al14O33,a inert binder,required a larger doped weight ratio（10%） to get the same performance as the former.