Characteristics of Ammonia Permeation Through Porous Silica Membranes
Characteristics of Ammonia Permeation Through Porous Silica Membranes
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DOI：
10.1002/aic.12059
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发表时间：
2010-05-01
期刊：
影响因子：
3.7
通讯作者：
Tsuru, Toshinori
中科院分区：
文献类型：
--
作者：
Kanezashi, Masakoto;Yamamoto, Akira;Tsuru, Toshinori
采用溶胶-凝胶法制备不同平均孔径的二氧化硅膜。通过测量单组分和二元组分分离，在宽温度范围（50-400 摄氏度）下检查了二氧化硅膜的氨 (NH3) 渗透/分离特性。通过二氧化硅膜的气体渗透率的顺序与膜平均孔径无关，如下：He>H-2>NH3>N-2。这些结果表明，对于通过二氧化硅膜的渗透，NH3 的分子尺寸大于 H-2 的分子尺寸，尽管之前的报道称 NH3 的动力学直径小于 H-2 的动力学直径。在高温下，NH3吸附对H-2渗透特性没有影响，并且二氧化硅膜在400℃下在NH3中高度稳定（即气体渗透率保持不变）。另一方面，在 50 摄氏度时，吸附在二氧化硅上的 NH3 分子通过阻止 H-2 分子的渗透而提高了 NH3 选择性渗透性，而不降低 NH3 渗透性。二元组分分离过程中获得的最大NH3/H-2渗透比接近于30，NH3渗透率接近于10(-7) mol m(-2) s(-1) Pa-1，H-2渗透活化能接近于6 kJ mol(-1)。 (C) 2009 美国化学工程师学会 AIChE J, 56: 1204-1212, 2010
A sol-gel method was applied for the preparation of silica membranes with different average pore sizes. Ammonia (NH3) permeation/separation characteristics of the silica membranes were examined in a wide temperature range (50-400 degrees C) by measurement of both single and binary component separation. The order of gas permeance through the silica membranes, which was independent of membrane average pore size, was as follows: He > H-2 > NH3 > N-2. These results suggest that, for permeation through silica membranes, the molecular size of NH3 is larger than that of H-2, despite previous reports that the kinetic diameter of NH3 is smaller than that of H-2. At high temperatures, there was no effect of NH3 adsorption on H-2 permeation characteristics, and silica membranes were highly stable in NH3 at 400 degrees C (i.e., gas permeance remained unchanged). On the other hand, at 50 degrees C NH3 molecules adsorbed on the silica improved NH3-permselectivity by blocking permeation of H-2 molecules without decreasing NH3 permeance. The maximal NH3/H-2 permeance ratio obtained during binary component separation was similar to 30 with an NH3 permeance of similar to 10(-7) mol m(-2) s(-1) Pa-1 at an H-2 permeation activation energy of similar to 6 kJ mol(-1). (C) 2009 American Institute of Chemical Engineers AIChE J, 56: 1204-1212, 2010