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RISS 인기검색어
- 검색키워드
- 저자 : Oleynikov, P. (검색결과 3 건)
- 무료
- 기관 내 무료
- 유료
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Structural Study of Hexagonal Close-Packed Silica Mesoporous Crystal
Ma, Yanhang,Han, Lu,Miyasaka, Keiichi,Oleynikov, Peter,Che, Shunai,Terasaki, Osamu American Chemical Society 2013 Chemistry of materials Vol.25 No.10
<P>Close-packed spheres can be stacked into two crystalline structures: cubic close-packed (ccp) and hexagonal close-packed (hcp). Both of these structures were found in silica mesoporous crystals (SMCs). Herein, pure hcp mesostructure with <I>P</I>6<SUB>3</SUB>/<I>mmc</I> symmetry of silica mesoporous crystals (SMCs) has been obtained in the synthetic system of cationic gemini surfactant as template and the <I>N</I>-[(3-trimethoxysilyl)propyl]ethylenediamine triacetix acid trisodium salt (EDTA-silyl) as the costructure directing agent (CSDA), which gives rise to the three-dimensional (3D) hexagonal structure and hexagonal plate morphology. The formation of the pure hcp structure was controlled by organic/inorganic interface curvature induced by charge matching between carboxylate groups of the CSDA and quaternary ammonium head groups of surfactant. Electrostatic potential distribution 3D map was reconstructed using Fourier analysis of HRTEM images based on electron crystallography, which showed characteristic features of the shape and connectivity of mesopores in the hcp structure. Small windows for connecting cages can be found only between layers, which determine the symmetry and local curvature of structures. As a result, the point group symmetry of mesopores becomes 6̅<I>m</I>2, instead of the <I>m</I>3̅<I>m</I> symmetry observed for perfect spheres in the ccp. The mechanism of stabilization and favorable growth of the pure hcp structure in mesoscale has been proposed based on synthesis strategy and symmetry support. This work provides people a better understanding of the priority of two sphere close-packed forms by comparing hcp and ccp structures.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/cmatex/2013/cmatex.2013.25.issue-10/cm401294j/production/images/medium/cm-2013-01294j_0001.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/cm401294j'>ACS Electronic Supporting Info</A></P>
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CO<sub>2</sub> capture from humid flue gases and humid atmosphere using a microporous coppersilicate
Datta, Shuvo Jit,Khumnoon, Chutharat,Lee, Zhen Hao,Moon, Won Kyung,Docao, Son,Nguyen, Thanh Huu,Hwang, In Chul,Moon, Dohyun,Oleynikov, Peter,Terasaki, Osamu,Yoon, Kyung Byung American Association for the Advancement of Scienc 2015 Science Vol.350 No.6258
<P><B>Grabbing CO<SUB>2</SUB> from wet gas streams</B></P><P>It is a challenge to extract CO<SUB>2</SUB> from typical gas streams, such as the flue gas from a power plant. This is because any water in the stream tends to prevent CO<SUB>2</SUB> absorption and may also degrade the absorbing material. Datte <I>et al.</I> developed a microporous copper silicate that avoids these problems. Most other materials have sites that absorb both water and CO<SUB>2</SUB> at the same sites, and in that fight, the water tends to win. Although their material still absorbs water, it has separate sites for the CO<SUB>2</SUB> absorption. It also shows good stability despite the absorbed water and can be reused.</P><P><I>Science</I>, this issue p. 302</P><P>Capturing CO<SUB>2</SUB> from humid flue gases and atmosphere with porous materials remains costly because prior dehydration of the gases is required. A large number of microporous materials with physical adsorption capacity have been developed as CO<SUB>2</SUB>-capturing materials. However, most of them suffer from CO<SUB>2</SUB> sorption capacity reduction or structure decomposition that is caused by co-adsorbed H<SUB>2</SUB>O when exposed to humid flue gases and atmosphere. We report a highly stable microporous coppersilicate. It has H<SUB>2</SUB>O-specific and CO<SUB>2</SUB>-specific adsorption sites but does not have H<SUB>2</SUB>O/CO<SUB>2</SUB>-sharing sites. Therefore, it readily adsorbs both H<SUB>2</SUB>O and CO<SUB>2</SUB> from the humid flue gases and atmosphere, but the adsorbing H<SUB>2</SUB>O does not interfere with the adsorption of CO<SUB>2</SUB>. It is also highly stable after adsorption of H<SUB>2</SUB>O and CO<SUB>2</SUB> because it was synthesized hydrothermally.</P>
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