Kinetic and Thermodynamic Characterization of Enhanced Carbon Dioxide Absorption Process with Lithium Oxide-Containing Ternary Molten Carbonate.
Kinetic and Thermodynamic Characterization of Enhanced Carbon Dioxide Absorption Process with Lithium Oxide-Containing Ternary Molten Carbonate.
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DOI：
10.1021/acs.est.6b02955
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发表时间：
2016-09
影响因子：
11.4
通讯作者：
Bowen Deng;Juanjuan Tang;X. Mao;Yuqiao Song;Hua Zhu;Wei Xiao;Dihua Wang
中科院分区：
文献类型：
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作者：
Bowen Deng;Juanjuan Tang;X. Mao;Yuqiao Song;Hua Zhu;Wei Xiao;Dihua Wang
高效、高通量的CO2捕集是CO2利用的前提。采用原位压力监测反应器研究了固体Li 2 O和熔融盐（不含Li 2 O和含Li 2 O的Li-Na-K碳酸盐）静态吸收CO2的过程。在723 K时，溶解态Li 2 O的吸收容量为0.835 molCO 2/molLi 2 O，大于固态Li 2 O。对于固体Li 2 O吸收剂，表面生成的固体Li 2CO 3阻碍了Li 2 O与CO2的进一步反应，而熔融碳酸盐对Li 2 O的解离/溶解作用提高了液体Li 2 O的质量比吸收容量。在含Li 2 O的Li-Na-K熔融碳酸盐中，CO2主要被碱性氧离子（O2-）吸收。CO2和CO 32-之间的化学相互作用通过形成多个碳酸根离子促进CO2吸收。这些吸收离子的传质被认为是静态吸收速率的主导因素。较高的温度降低了CO2吸收的热力学趋势，但在高温下较低的粘度有利于吸收动力学。与常用的CaO吸收剂相比，Li_2O在熔融碳酸盐中的溶解度更高。含Li 2 O的熔融碳酸盐是一种潜在的工业碳捕集和电化学转化过程的介质。
Efficient and high-flux capture of CO2 is the prerequisite of its utilization. Static absorption of CO2 with solid Li2O and molten salts (Li2O-free and Li2O-containing Li-Na-K carbonates) was investigated using a reactor with in situ pressure monitoring. The absorption capacity of dissolved Li2O was 0.835 molCO2/molLi2O at 723 K, larger than that of solid Li2O. For the solid Li2O absorbents, formation of solid Li2CO3 on the surface can retard the further reactions between Li2O and CO2, whereas the dissociation/dissolution effect of molten carbonate on Li2O improved the mass-specific absorption capacity of liquid Li2O. In Li2O-containing Li-Na-K molten carbonate, CO2 was mostly absorbed by alkaline oxide ions (O2-). The chemical interactions between CO2 and CO32- contributed to CO2 uptake via formation of multiple carbonate ions. The mass transfer of these absorbing ions was found as the dominating factor governing the rate of static absorption. Higher temperatures reduced the thermodynamic tendency of CO2 absorption, but a lower viscosity at elevated temperature was conducive to absorption kinetics. Compared with the commonly used CaO absorbent, Li2O was much more dissolvable in molten carbonate. The Li2O-containing molten carbonate is potentially a promising medium for industrial carbon capture and electrochemical transformation process.