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首页> 外文期刊>Environmental Science & Technology >H_2CO_3(s): A New Candidate for CO_2 Capture and Sequestration
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H_2CO_3(s): A New Candidate for CO_2 Capture and Sequestration

机译：H_2CO_3（s）：CO_2捕获和封存的新候选人

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摘要

To reduce the magnitude of anthropogenic global warming it is necessary to remove CO_2(g) from the effluent streams of coal-fired power plants and to sequester the CO_2 either as a liquid or by reaction with other compounds. A major difficulty in achieving this goal arises from the very weak acidity of CO_2(g), causing it to react only incompletely with weak bases, although this weak interaction does provide a means for "stripping" the CO_2 from the acid-base complex at high temperatures. Reaction with strong bases like NaOH yields more stable complexes, but massive amounts of chemical reactants would need to be purchased and chemical products like NaHCO_3then stored. However, when gas-phase CO_2 reacts with the weak base water (or when bicarbonate reacts with strong acid) the unstable product monomeric "H_2CO_3" can be formed. The free energy required is about 16 kcal/mol in the gas phase and about 10 kcal/mol in aqueous solution. This energy can be supplied by particle or photon excitation and is only a small fraction of the energy released when a mole of CH_4 is converted to a mole of CO_2. Although this monomeric compound is highly unstable, its oligomers are considerably more stable, due to internal H-bonding, with free energies for the larger oligomers in the gas phase which are about 4 kcal/(mol of H_2CO_3) lower, onfy about 6 kcal/mol H_2CO_3 higher than the gas-phase combination of CO_2 and H_2O at room temperature. Also, at lower temperature the entropic penalty for the oligomer is less and oligomeric H_2CO_3 becomes stable around the sublimation temperature of dry ice. This indicates that it may be possible to capture gas-phase CO_2 directly, using only cheap and abundant H_2O as a reactant, and to store the resulting (H_2CO_3)_n as a oligomeric solid at only moderately coid temperatures. These conclusions are based on quantum computations that accurately reproduce the structures, spectra, and stabilities of H_2CO_3. oligomers. Methods for producing and characterizing the H_2CO_3 oligomers are discussed. However, some aspects of the proposed scheme are quite speculative and will require additional investigation. Several important questions need to be answered before the feasibility of this procedure on a planetary scale can be assessed, particularly those involving the vapor pressure curve, heat of sublimation, density, and compressibility of (H_2CO_3)_n.
机译：为了减少人为造成的全球变暖的程度，有必要从燃煤电厂的污水流中去除CO_2（g），并以液态或通过与其他化合物反应的方式隔离CO_2。实现此目标的主要困难来自于非常弱的CO_2（g）酸度，导致其仅与弱碱不完全反应，尽管这种弱相互作用确实提供了将CO_2从酸碱配合物中“剥离”的方法。高温。与强碱（如NaOH）反应可生成更稳定的配合物，但需要购买大量化学反应物，然后存储化学产品（如NaHCO_3）。然而，当气相CO_2与弱碱水反应时（或当碳酸氢盐与强酸反应时），会形成不稳定的产物单体“ H_2CO_3”。在气相中所需的自由能为约16kcal / mol，在水溶液中为约10kcal / mol。该能量可以通过粒子或光子激发来提供，仅是当一摩尔CH_4转化为一摩尔CO_2时释放的能量的一小部分。尽管该单体化合物非常不稳定，但由于内部氢键的缘故，其低聚物相当稳定，气相中较大的低聚物的自由能低约4 kcal /（H_2CO_3摩尔），约6 kcal / mol H_2CO_3高于室温下CO_2和H_2O的气相组合。同样，在较低温度下，低聚物的熵损失较小，并且低聚物H_2CO_3在干冰的升华温度附近变得稳定。这表明有可能仅使用廉价且丰富的H_2O作为反应物直接捕获气相CO_2，并仅在中等温度下以低聚固体形式存储所得的（H_2CO_3）_n。这些结论是基于量子计算得出的，该计算精确地再现了H_2CO_3的结构，光谱和稳定性。低聚物。讨论了制备和表征H_2CO_3低聚物的方法。但是，提议的方案的某些方面是推测性的，将需要进一步的研究。在评估此方法在行星规模上的可行性之前，需要回答几个重要问题，特别是涉及蒸气压曲线，升华热，密度和（H_2CO_3）_n可压缩性的问题。

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  • 来源
    《Environmental Science & Technology》 |2009年第7期|2575-2580|共6页
  • 作者

    I.A. TOSSELL;

  • 作者单位

    Department of Chemistry and Biochemistry, University of Maryland College Park, Maryland 20742 The RenewableEnergy Institute, George Washington University,Washington, D.C. 20052;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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  • 正文语种 eng
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