用X光衍射法研究丝光沸石的阳离子交换

STUDYING THE CATION EXCHANGE OF SYNTHETIC MORDENITE WITH X-RAY POWDER DIFFRACTION METHOD

丝光沸石的催化性能与其所含阳离子的种类、位置有密切关系.R.M.Barrer,F.Wolf等广泛研究了合成丝光沸石的阳离子交换,由离子交换等温线推论交换过程的性质.本文试图以X光衍射法来研究离子交换过程,观察X光衍射图谱随交换度的变化关系,获得有关交换的一些信息.显然,若交换过程伴随着脱铝,亦会引起X光衍射图谱与晶格常数的改变.因此,必须选择适当的体系使交换时不存在骨架的脱铝. 鉴于在丝光沸石的催化研究中,酸交换与铝交换具有特殊重要性,本文研究了下列两个体系: (1)在25℃,以约0.04N的HAC溶液(pH≥3.1)交换合成NaM.据R.M.

In order to get some information about the process of the cation exchange of synthetic mordenite, X-ray diffraction patterns of samples with various extent of cation exchange of HAC and A1C1_2 on NaM were studied. The patterns of these two systems were so similar that Aluminum cation exchange was regarded mostly as acid exchange. The patterns changed regularly with the extent of cation exchange. In acid system the plot of △(2θ) between (12 0 2) and (1 9 4) against the extent of exchange degree gave a curve consisting of two straight lines with different slopes. The transition point was near 30% exchange degree. It was suggested that two different exchange sites existed in the zeolite.