Role of Water in SSIE

The acidic OH groups of H-L (nsj/uAi = 3.18) completely disappeared and were markedly decreased in the case of H-MOR (nsi/n i = 6.78). The fact that with H-MOR not all of the OH groups were replaced by La + is easily understood if one takes into account the high nsi/n i ratio similar to H-ZSM-5 (cf. Sect. 5.2.4), the distance between the acid OH groups is larger than in regular fauja-site-type H-Y (nsi/n i = 2.5) or H-L and it is, therefore, more difficult to com- 

In contrast, water-free LaCl3 did not exchange with H-ferrierite at all,i.e.,no decrease in the OH bands was observed indicating the failure of SSIE. The latter result will be discussed in Sect. 7.2. 

By a comparative experiment similar to that reported in Sect. 5.2.5, the incorporation of La + cations from water-free LaCls into H-L, H-MOR and H-S-Y was qualitatively confirmed by the changes in the intensities of the corresponding framework reflections in the XRD patterns. These were obtained in situ under high vacuum in a heatable XRD chamber [287]. No changes in the XRD reflections of the framework of ferrierite were observed upon calcination of a LaCl3/H-FER mixture which confirms the IR results reported above. 

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Sections 5.1 and 5.2 dealt with solid-state ion exchange with M + salts (M = Mg or Ca) and La + chloride, respectively. However, in these cases, the salts were initially not water-free but contained physically adsorbed and crystal water. The role of water in SSIE will be discussed in detail in Sect. 7.1. 

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