An oriented, siliceous deca-dodecasil 3R (DDR) zeolite film for effective carbon capture: insight into its hydrophobic effect
An oriented, siliceous deca-dodecasil 3R (DDR) zeolite film for effective carbon capture: insight into its hydrophobic effect
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DOI：
10.1039/c7ta02462b
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发表时间：
2017-06-14
影响因子：
11.9
通讯作者：
Choi, Jungkyu
中科院分区：
文献类型：
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作者：
Kim, Eunjoo;Hong, Sungwon;Choi, Jungkyu
孔径为0.36 x 0.44 nm（2）的全硅十-十二硅基3R（Si-DDR）沸石对于CO2（0.33 nm）与N-2（0.364 nm）的膜基分离是非常理想的，这在燃烧后碳捕获过程中是至关重要的，通过分子识别它们的微小尺寸差异。我们首次采用结构导向剂碘化甲基托品的方法，通过外延生长DDR晶种层，获得了h0h取向的疏水性DDR沸石薄膜。随着二次生长时间的增加，面外取向和互生长的程度增加，同时减少了提供非选择性路径的缺陷。所得DDR膜在干燥条件下在50 ℃（代表性烟道气温度）下显示出高达11.9的CO2/N-2分离因子（SF）。更理想地，在H2O蒸气（烟道气中的第三大组分）存在下，在50 ℃下，它可以实现高达15.9的大大提高的CO2/N-2SF。吸附在膜表面的H2O分子对较大的N-2分子进入DDR分子筛的孔道的传输有更大的抑制作用，这种表面阻力是由于高硅DDR膜的疏水性，有利于改善湿润条件下的CO2/N-2 SFs。
An all-silica deca-dodecasil 3R (Si-DDR) zeolite with a pore size of 0.36 x 0.44 nm(2) is highly desirable for membrane-based separation of CO2 (0.33 nm) from N-2 (0.364 nm), which is critical in the post-combustion carbon capture process, via molecular recognition of their slight size difference. For the first time, we acquired h0h-oriented, hydrophobic DDR zeolite films through the epitaxial growth of a DDR seed layer with a structure directing agent of methyltropinium iodide. The degree of the out-of-plane orientation and inter-growth was increased with the secondary growth time, while reducing the defects that provide non-selective pathways. The resulting DDR membrane showed a CO2/N-2 separation factor (SF) as high as 11.9 at 50 degrees C (a representative flue-gas temperature) under dry conditions. More desirably, it could achieve a much enhanced CO2/N-2 SF of up to 15.9 at 50 degrees C in the presence of H2O vapor (3rd largest component in the flue-gas). The transport of the larger N-2 molecule, plausibly its entering the pore mouth of DDR zeolites, was more inhibited by H2O molecules adsorbed on the membrane surface; it appears that this surface resistance was due to the hydrophobicity of the highly siliceous DDR membrane and beneficial for improving CO2/N-2 SFs under wet conditions.