PREPARATION OF MICROCHANNEL MATERIALS FOR SEPARATION OF ORGANIC COMPOUNDS

采用溶胶-凝胶法制备了四乙氧基硅烷（TEOS）和辛基、十二烷基或十八烷基三乙氧基硅烷，在-氧化铝包覆的α -氧化铝管上形成了多孔硅膜。以烷基三乙氧基硅烷为模板来控制孔径。研究了烷基长度对硅膜孔结构和渗透性能的影响。溶胶中水与总烷氧化物的摩尔比x对孔隙结构有很大影响。用十八烷基三乙氧基硅烷制备的硅膜存在介孔和裂纹，而用十二烷基三乙氧基硅烷制备的硅膜则无缺陷。对不同分子尺寸气体的渗透实验表明，在600℃下煅烧的二氧化硅膜的微孔主要分布在0.3 ~ 0.4 nm范围内。这些微孔基本是通过模板中烷基链的分解形成的，而中孔结构是在凝胶化过程中形成的。

Porous silica membranes were formed by a sal-gel technique on a gamma-alumina-coated alpha-alumina tube using sols which were prepared from tetraethoxysilane (TEOS) and octyl-, dodecyl, or octadecyltriethoxysilane. The alkyltriethoxysilanes were used as the template to control the pore size. The effect of the length of alkyl groups on pore structure as well as the permeation properties of the silica membranes were then investigated. The molar ratio of water to total alkoxides in the sols, x, strongly influenced the pore structure. A silica membrane which was prepared with octadecyltriethoxysilane contained mesopores and cracks, but the silica membranes prepared octyl- and dodecyltriethoxysilane were defect-free. Permeations to gasses with a variety of molecular sizes showed that the majority of micropores were in the 0.3-0.4 nm range for the silica membranes which had been calcinated at 600ﾟC.These micropores were basically formed by the decomposition of alkyl chains in the template, while the mesopore structure was achieved during the gelation step.