Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States.
J Am Chem Soc. 2011 Jan 26;133(3):493-502. doi: 10.1021/ja107942n. Epub 2010 Dec 16.
Zeolite nanocrystals were prepared from three-dimensionally ordered mesoporous-imprinted (3DOm-i) silicalite-1 by a fragmentation method involving sonication and dissolution within a certain pH range. 3DOm-i silicalite-1 with spherical elements with diameters ranging from 10 to 40 nm and a wide range of crystal sizes (100-200 nm, 500-600 nm, and 1-2 μm) was used as the starting material. The highest yield (57%) of isolated nanocrystals was obtained for 3DOm-i silicalite-1 with a crystal size of 100-200 nm and a spherical element diameter of 40 nm. The smallest nanocrystals obtained, albeit in very low yields, had a 10 nm diameter. Preparation of stable silicalite-1 nanocrystal suspensions fragmented from 20 and 40 nm 3DOm-i silicalite-1 was demonstrated. Cryogenic transmission electron microscopy showed that the isolated zeolite nanocrystals can be used as seeds for the epitaxial growth of silicalite-1. An application of these findings was demonstrated: silicalite-1 nanocrystal suspensions were used to deposit seed layers on porous α-alumina disks, which were converted to continuous thin (300-400 nm) films by secondary growth that exhibited both high permeances and separation factors (3.5 × 10(-7) mol m(-2) s(-1) Pa(-1) and 94-120, respectively, at 150 °C) for p- and o-xylene.
沸石纳米晶体是通过超声和在一定 pH 范围内溶解的碎裂方法从三维有序介孔印迹（3DOm-i）硅沸石-1 制备的。使用具有直径在 10 至 40nm 之间且晶体尺寸范围广泛（100-200nm、500-600nm 和 1-2μm）的球形元素的 3DOm-i 硅沸石-1 作为起始材料。对于晶体尺寸为 100-200nm 和球形元素直径为 40nm 的 3DOm-i 硅沸石-1，获得了最高的分离纳米晶体产率（57%）。尽管产率非常低，但获得了最小的纳米晶体，直径为 10nm。证明了可以从 20nm 和 40nm 的 3DOm-i 硅沸石-1 制备稳定的硅沸石-1 纳米晶体悬浮液。低温传输电子显微镜显示，分离的沸石纳米晶体可用作硅沸石-1 外延生长的种子。这些发现的一个应用是：硅沸石-1 纳米晶体悬浮液用于在多孔α-氧化铝盘上沉积种子层，然后通过二次生长将其转化为连续的薄（300-400nm）膜，该膜在 150°C 时表现出高渗透性和分离因子（分别为 3.5×10(-7)mol m(-2) s(-1) Pa(-1)和 94-120），用于对二甲苯和邻二甲苯。
