Change in pore structure of MFI zeolite by treatment with NaOH aqueous solution
Change in pore structure of MFI zeolite by treatment with NaOH aqueous solution
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DOI：
10.1016/s1387-1811(00)00349-8
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发表时间：
2001-03-01
影响因子：
5.2
通讯作者：
Okuhara, T
中科院分区：
文献类型：
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作者：
Suzuki, T;Okuhara, T
在323 ~ 343 K的温度范围内，通过对Ar和N-2的吸附，研究了NaOH水溶液（0.05 mol dm(-3)）对Si/Al = 37的MFI分子筛孔径和孔体积的影响。总表面积（BET表面积）在处理初期呈上升趋势，而后缓慢下降。总表面积的变化归因于外表面积的变化。对N-2吸附等温线的BJH分析表明，NaOH处理形成了宽度约1.8 nm的超微孔。此外，Saito-Foley吸附等温线分析表明，naoh处理后微孔的大小和体积几乎没有变化。元素分析表明，处理后的MFT沸石中约30%的Si被溶解，而Al只释放了百分之几。这些结果表明，晶体相的框架在naoh处理下是稳定的，并且可能存在于晶体边界的非晶态相溶解形成超微孔，支持先前的报告[Chem。列托人。(2000) 882)。(C) 2001 Elsevier Science B.V.版权所有
Changes of the pore size and the pore volume of MFI zeolite (Si/Al = 37) upon treatment with an NaOH aqueous solution (0.05 mol dm(-3)) have been investigated at the temperature range from 323 to 343 K by means of adsorptions of Ar and N-2. The total surface area (BET surface area) increased at the initial stage of the treatment and then decreased slowly. The change of the total surface area was attributed to that of the external surface area. BJH analysis of the N-2 adsorption isotherm revealed that the supermicropores having a width of about 1.8 nm were created by the treatment of NaOH. In addition, Saito-Foley analysis of the Ar adsorption isotherm showed that the size and the volume of the micropores remained almost unchanged after the NaOH-treatment. It was evident from elemental analysis that about 30% Si of the MFT zeolite was dissolved by the treatment, while only a few percent of Al was released. These results demonstrate that the framework of the crystalline phase was stable against the NaOH-treatment and probably the amorphous phases present at the boundary of the crystallites dissolved to form the supermicropores, supporting a previous report [Chem. Lett. (2000) 882]. (C) 2001 Elsevier Science B.V. All rights reserved.