Reactivation and remaking of calcium aluminate pellets for CO2 capture
Reactivation and remaking of calcium aluminate pellets for CO2 capture
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DOI：
10.1016/j.fuel.2010.07.054
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发表时间：
2011
期刊：
影响因子：
7.4
通讯作者：
V. Manović;E. Anthony
中科院分区：
文献类型：
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作者：
V. Manović;E. Anthony
CaO基球团与铝酸盐水泥支持显示出上级的性能，在碳酸化/煅烧循环高温CO2捕获。然而，与其他CaO基吸收剂一样，在高温、高CO2浓度条件下循环次数增加后，其CO2携带活性降低。在这项工作中，他们的再生的可行性进行了研究，蒸汽或水和重塑（重塑）。在热重分析仪（TGA）中测试由三种石灰石、Cadomin和Havelock（加拿大）和Katowice（波兰，上西里西亚）制备的粒料。这些循环是在现实的CO2捕获条件下进行的，包括在高达950°C的温度下在100% CO2中煅烧。典型地，在30个循环之后，在实验室蒸汽反应器（SR）中用100°C的饱和蒸汽将样品水合5分钟。此外，更大量的颗粒在管式炉（TF）中循环，用水水合并重塑，并在TGA中测试以确定其CO2捕获活性。结果发现，在水合阶段之后，颗粒恢复了它们的活性，更有趣的是，经历了更长系列循环的颗粒对再活化反应更有利。此外，发现丸粒的转化率在约70次循环后增加（23%），在约210次循环时达到33%，没有再活化步骤。扫描电子显微镜（SEM）分析表明，在循环过程中，在颗粒表面形成的低孔隙度壳的形态，这限制了转化，在短时间（5分钟）的蒸汽水合后被消除。在TF中循环的再成形废颗粒的氮物理吸附分析（BET，BJH）证实，吸附剂表面积和孔径分布与原始颗粒的那些相似。经XRD分析，再生球团中的主要氧化铝化合物为钙铝石（Ca_（12）Al_（14）O_（33））。这些结果表明，通过定期水合/重塑步骤，无论捕获/再生条件如何，颗粒都可以在CO2循环周期中使用更长时间。
CaO-based pellets supported with aluminate cements show superior performance in carbonation/calcination cycles for high-temperature CO2capture. However, like other CaO-based sorbents, their CO2carrying activity is reduced after increasing numbers of cycles under high-temperature, high-CO2concentration conditions. In this work the feasibility of their reactivation by steam or water and remaking (reshaping) was investigated. The pellets, prepared from three limestones, Cadomin and Havelock (Canada) and Katowice (Poland, Upper Silesia), were tested in a thermogravimetric analyzer (TGA). The cycles were performed under realistic CO2capture conditions, which included calcination in 100% CO2at temperatures up to 950°C. Typically, after 30 cycles, samples were hydrated for 5min with saturated steam at 100°C in a laboratory steam reactor (SR). Moreover, larger amounts of pellets were cycled in a tube furnace (TF), hydrated with water and reshaped, and tested to determine their CO2capture activity in the TGA. It was found that, after the hydration stage, pellets recovered their activity, and more interestingly, pellets that had experienced a longer series of cycles responded more favorably to reactivation. Moreover, it was found that conversion of pellets increased after about 70 cycles (23%), reaching 33% by about cycle 210, with no reactivation step. Scanning electron microscope (SEM) analyses showed that the morphology of the low-porosity shell formed at the pellet surface during cycles, which limits conversion, was eliminated after a short period (5min) of steam hydration. The nitrogen physisorption analyses (BET, BJH) of reshaped spent pellets from cycles in the TF confirmed that sorbent surface area and pore size distribution were similar to those of the original pellets. The main alumina compound in remade pellets as determined by XRD was mayenite (Ca12Al14O33). These results showed that, with periodic hydration/remaking steps, pellets can be used for extended times in CO2looping cycles, regardless of capture/regeneration conditions.