微型多孔材料
沸石
传质
分析化学(期刊)
扩散
化学
动力学
Crystal(编程语言)
热扩散率
扫描电子显微镜
单晶
材料科学
结晶学
色谱法
热力学
催化作用
复合材料
量子力学
物理
生物化学
有机化学
程序设计语言
计算机科学
作者
Yu Wang,Karl G. Strohmaier,Michael Strasser
摘要
Abstract A new concentration‐swing frequency response system was developed to evaluate water kinetics in non‐binder containing zeolite Linde Type A ( LTA ) crystals with frequencies up to 1 Hz. For commercial micron‐sized 3A crystals, the mass transfer rate is too fast to be determined accurately due to reduced sensitivity near the system limits. Larger LTA crystals (~15 μm) were synthesized in house and ion exchanged to three potassium concentrations (0, 48, and 77 wt%) to aid in the accurate determination of mass transfer mechanism and rates. Micropore diffusion with parallel sites, not a surface barrier, described all the data well, consistent with the bimodal distribution of crystal sizes from scanning electron microscope images. The transport diffusivity for water in zeolite 3A crystals near saturated loadings at 25°C is about 1 × 10 −12 m 2 /s, 10 times slower than 4A crystals around 10 −11 m 2 /s, both supporting fast micropore diffusion time constants >1 s −1 for micron‐sized crystals.
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