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Micropore structure stabilization in organosilica membranes by gaseous catalyst post-treatment
Journal of Membrane Science ( IF 8.4 ) Pub Date : 2018-02-01 , DOI: 10.1016/j.memsci.2017.11.014
A. Petra Dral , Ernst R.H. van Eck , Louis Winnubst , Johan E. ten Elshof

Abstract A post-treatment involving repeated exposure to gaseous HCl alternated with heating is demonstrated to strongly accelerate the recently reported structural evolution in organically bridged silica networks. Films, powders and membranes derived from 1,2-bis(triethoxysilyl)ethane were exposed to in-situ synthesized HCl gas, alternated with heat treatments at 150–300 °C in air or N2. The film thickness, network condensation, chemical integrity and micropore structure were monitored with X-ray reflectivity, 29Si direct-excitation magic-angle spinning nuclear magnetic resonance, Fourier-transform infrared spectroscopy and gas permeation. Treatment with HCl was found to predominantly catalyze hydrolysis, enabling network optimization via iterative bond breakage and reformation. Network shrinkage, widening or opening of the smallest pores and densification of the overall pore structure were accelerated while the ethylene bridges remained intact. The achieved acceleration of material evolution makes iterative hydrolysis and condensation a promising approach for increasing the long-term micropore stability of molecular sieving membranes.

中文翻译:

气态催化剂后处理稳定有机硅膜微孔结构

摘要 涉及反复暴露于气态 HCl 和加热交替的后处理被证明可以强烈加速最近报道的有机桥接二氧化硅网络的结构演变。将源自 1,2-双(三乙氧基甲硅烷基)乙烷的薄膜、粉末和膜暴露于原位合成的 HCl 气体中,并在空气或 N2 中在 150-300°C 下进行热处理。通过X射线反射率、29Si直接激发魔角自旋核磁共振、傅里叶变换红外光谱和气体渗透监测膜厚度、网络凝聚、化学完整性和微孔结构。发现用 HCl 处理主要催化水解,通过反复键断裂和重整实现网络优化。网络收缩,在乙烯桥保持​​完整的情况下,最小孔的加宽或打开以及整个孔结构的致密化得到加速。实现的材料演化加速使迭代水解和缩合成为提高分子筛膜长期微孔稳定性的有前途的方法。
更新日期:2018-02-01
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