介孔材料
沸石
微晶
微型多孔材料
煅烧
材料科学
化学工程
硅酸铝
结晶度
吸附
打赌理论
分子筛
比表面积
无机化学
催化作用
化学
有机化学
复合材料
冶金
工程类
作者
Songhyun Lee,Hyeonbin Kim,Minkee Choi
出处
期刊:Journal of materials chemistry. A, Materials for energy and sustainability
[The Royal Society of Chemistry]
日期:2013-01-01
卷期号:1 (39): 12096-12096
被引量:23
摘要
Controlled decationization (ion exchange with NH4+ and subsequent calcination) of NaX zeolite could produce hierarchically micro-/mesoporous aluminosilicates with systematically variable micro- and mesoporosity. As the Na/Al ratio was decreased from 1 to 0.5, secondary mesoporosity gradually increased up to 0.18 mL g−1 at the cost of initial microporosity while maintaining the total pore volume (>0.41 mL g−1) and BET surface area (>630 m2 g−1). On excessive decationization (Na/Al < 0.5), there was no more increase in the mesopore volume, but the microporosity and zeolite crystallinity decreased further. As a result, the fully decationized sample exhibited a solely mesoporous structure but still had a considerable BET surface area (328 m2 g−1). TEM and N2 adsorption–desorption isotherms showed that mesopores were evenly distributed over the entire domain of zeolite crystallites. In contrast, conventional dealumination methods using chemical leaching with HCl and Na2H2EDTA showed heterogeneous destruction of zeolite crystallites: the external rim of the crystallites was heavily damaged to form amorphous mesoporous silicates, but the core of the zeolite crystallite remained intact and solely microporous. The present decationization method provides an extremely economic and simple synthesis route to obtain mesoporous and hierarchically micro-/mesoporous aluminosilicates, which are promising as adsorbents and heterogeneous catalysts for large molecular species.
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