摘要
采用溶胶-凝胶法制备了掺杂La3+、Mg2+的复合钙基CO2吸收剂,并在固定床反应器上进行了多循环的煅烧/碳化实验,对其CO2吸收活性及循环反应稳定性进行了研究。实验结果表明,掺杂La3+、Mg2+的复合钙基吸收剂可以显著提高吸收剂在多循环煅烧/碳化过程中的反应活性和循环稳定性。在XRD分析的基础上,计算和比较了不同钙基吸收剂CaO的微晶参数,发现掺杂La3+、Mg2+制备的氧化钙吸收剂可以有效地减小CaO晶粒的尺寸。同时,通过FSEM图像分析,发现掺杂La2O3制备的复合钙基吸收剂有一定程度的烧结现象发生,但由于掺杂的La3+可以进入CaO晶体与Ca2+发生不等价取代,导致阳离子空位增加,使晶格活化,有利于在碳化过程中与CO2发生反应,从而大大提高吸收剂的反应活性。
Regeneratable CaO-based sorbents for CO2 capture during coal combustion process are receiving more and more attention. Unfortunately, the CO2 sorbtion capacity of CaO-sorbents based on natural limestone decreases rapidly with times of capture-and-release cycle because of severe sintering. This sintering can be effectively mitigated by properly doping metal oxides. In this paper an attempt was done to prepare a class of synthetic CaO/La203 and CaO/MgO sorbents by sol-gel method. The CO2 sorption capacity of these doped CaO-based sorbents in multi-cycles and the effect of additive La^3＋ or Mg^2＋ were investigated in a fixed bed reactor. The results show that additive of La2 03 or MgO） plays a positive role in the multiple capture/regeneration reactions. Based on XRD analysis, it is concluded that addition of La^3＋ or Mg^2＋ can significantly reduced the crystalline size of CaO. Furthermore, it is also showed from FSEM images analysis that the CaO-based sorbents doped La^3＋ also have certain degree sintering. However, the La^3＋ can get into CaO crystal, resulting in activation of CaO lattice and increase of cation vacancy, which can plays a positive role in the process of capturing CO2, thereby greatly improve the reactivity of these sorbents.
出处
《化工学报》
EI
CAS
CSCD
北大核心
2011年第10期2905-2913,共9页
CIESC Journal
基金
国家重点基础研究发展计划项目(2011CB707301)
国家自然科学基金项目(50936001
51021065)~~
关键词
CO2捕集
钙基吸收剂
掺杂
晶粒尺寸
CO2 capture
CaO-based sorbents
doped CaO
crystalline size
