Polyamine-Tethered Porous Polymer Networks for Carbon Dioxide Capture from Flue Gas
Polyamine-Tethered Porous Polymer Networks for Carbon Dioxide Capture from Flue Gas
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DOI：
10.1002/anie.201202176
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发表时间：
2012-01-01
影响因子：
16.6
通讯作者：
Zhou, Hong-Cai
中科院分区：
文献类型：
--
作者：
Lu, Weigang;Sculley, Julian P.;Zhou, Hong-Cai
我们这个时代最紧迫的环境问题之一是大气中二氧化碳水平的不断上升，这在很大程度上与化石燃料的燃烧有关。然而，在可预见的未来，似乎不断增长的能源需求将很可能需要消耗这些不可或缺的能源。碳捕获和封存（CCS）是一种从燃煤发电厂的烟气中分离二氧化碳然后将其储存在地下的过程，已被提议用于减少人为二氧化碳排放。目前在世界范围内的发电厂中采用的CO2捕集方法是燃烧后“湿法洗涤”方法，其涉及通过胺溶液如单乙醇胺（MEA）化学吸附CO2。由两个MEA分子和一个CO2分子形成氨基甲酸酯赋予洗涤器对CO2的高容量和选择性。然而，该方法存在一系列固有的问题，例如加热溶液引起的高再生成本（ca. 30%的工厂生产的电力），设备结垢，和溶剂蒸发。[1]为了避开传统湿式洗涤器的巨大能量需求、腐蚀问题和其他限制，已经进行了大量的努力来研究使用固体吸附剂作为替代方法。[2]与其中在溶解的胺的再生期间必须加热和冷却大量水（70%w/w）的湿法洗涤相比，固体吸附剂方法具有通过消除对加热水的需要而提高再生过程的能量效率的巨大优势。多孔材料，如MOF-210，[3] NU-100，[4]和PPN-4，[5]已被认为是可行的存储替代品，因为它们的高孔隙率，因此，显着增加了与气体分子的接触面积。这可能是有利的，因为与胺湿法洗涤系统相比，分离和再生可以在相对温和的条件下进行。不幸的是，创纪录的高储存能力并没有转化为高选择性，在碳捕获条件下仅观察到中等的CO2吸收能力。CO2的极化率和大的四极矩可以通过引入在材料表面和CO2之间产生强相互作用的亲CO2部分来利用。这将提高CO2相对于其他气体的负载能力和选择性。事实上，这种方法已经被证明在提高CO2吸附焓方面非常成功，[6]可以从不同温度下的CO2吸附等温线计算，并用于量化材料与CO2之间的相互作用。值得指出的是，材料的孔隙率将因官能团的引入而受到损害。环境条件下的CO2负载能力取决于吸附焓和孔隙率（表面积和孔体积），必须平衡它们才能实现高负载。除了负载能力之外，量化材料性能的另一个重要因素是CO2对N2的选择性。以胺洗涤为模型，已合成的胺化多孔材料通常表现出非常大的CO2吸附容量和高CO2/N2选择性。最近，Long和他的同事证明了在CuBTTri（H3 BTTri = 1，3，5-三（1H-1，2，3-三唑-4-基）苯）的暴露金属中心处引入N，N-二甲基乙二胺（mmen），新化合物mmen-CuBTTri显示出在低压下显著增强CO2吸收，以及CO2/N2比。
One of the most pressing environmental concerns of our age is the escalating level of atmospheric CO2, which is largely correlated to the combustion of fossil fuels. For the foreseeable future, however, it seems that the ever-growing energy demand will most likely necessitate the consumption of these indispensable sources of energy. Carbon capture and sequestration (CCS), a process to separate CO2 from the flue gas of coal-fired power plants and then store it underground, has been proposed to reduce the anthropogenic CO2 emissions. Current CO2 capture processes employed in power plants worldwide are post-combustion “wet scrubbing” methods involving the chemical adsorption of CO2 by amine solutions such as monoethanolamine (MEA). The formation of carbamate from two MEA molecules and one CO2 molecule endows the scrubber with a high capacity and selectivity for CO2. However, this process suffers from a series of inherent problems, such as high regeneration costs that arise from heating the solution (ca. 30% of the power produced by the plant), fouling of the equipment, and solvent boil-off.[1] To sidestep the huge energy demand, corrosion problem, and other limitations of traditional wet scrubbers, intensive efforts have been made to investigate the use of solid adsorbents as an alternative approach.[2] Compared to wet scrubbing, in which a large amount of water (70% w/w) must be heated and cooled during the regeneration of the dissolved amines, the solid adsorbent approach has the tremendous advantage of improving the energy efficiency of the regeneration process by eliminating the need to heat water. Porous materials, such as MOF-210,[3] NU-100,[4] and PPN-4,[5] have been deemed to be viable storage alternatives because of their high porosity and, therefore, significantly increased accessible contact area with gas molecules. This could be advantageous because separation and regeneration could be performed under relatively mild conditions compared to amine wet scrubbing systems. Unfortunately, the record high storage capacities do not translate to high selectivities and only moderate CO2-uptake capacities were observed under carbon capture conditions. The polarizability and large quadrupole moment of CO2 can be taken advantage of by introducing CO2-philic moieties that create strong interactions between the material surface and the CO2. This will improve the loading capacities and selectivity of CO2 over other gases. Indeed, this approach has already been proven to be very successful in enhancing the enthalpy of CO2 adsorption,[6] which can be calculated from CO2 sorption isotherms at different temperatures and used to quantify the interaction between the material and CO2. It is worth pointing out that the porosity of the material will be compromised by the introduction of functional groups. CO2 loading capacities at ambient conditions are dependent on the adsorption enthalpy and porosity (both surface area and pore volume), which must be balanced to achieve high loading. Besides the loading capacity, another important factor when quantifying how well a material will perform is CO2 selectivity over N2. Taking amine scrubbing as the model, aminated porous materials that have been synthesized usually exhibit very large adsorption enthalpies for CO2 and high CO2/N2 selectivities. Recently, Long and co-workers demonstrated the incorporation of N, N-dimethylethylenediamine (mmen) at exposed metal centers of CuBTTri (H3BTTri= 1, 3, 5-tri (1H-1, 2, 3-triazol-4-yl) benzene), with the new compound mmen-CuBTTri showing drastic enhancement of CO2 uptake at low pressure, as well as CO2/N2 …