TS1分子筛晶化过程的研究

STUDY ON CRYSTALLIZATION PROCESS OF TITANIUM SILICALITE 1

采用ＩＣＰＡＥＳ， ＴＥＭ， ＸＲＤ，ＦＴＩＲ 和ＦＴＲａｍａｎ 等技术研究了ＴＳ１ 分子筛的晶化过程． 结果表明，ＴＳ１ 分子筛的晶化过程从无定形ＳｉＯ２ 颗粒开始生长，以ＳｉＯ２ 颗粒的外表面为晶核不断发展，晶化过程的第一小时内主要以无定形的ＳｉＯ２ＴｉＯ２ 共凝胶颗粒存在，１ ｈ 后开始迅速形成ＴＳ１ 晶粒，ＴＳ１ 晶粒的生成与无定形ＳｉＯ２ 的消失同时发生，８ ｈ 后基本上完成ＴＳ１ 分子筛的成长，结晶度达到９５ ％ ， 形成完善的ＭＦＩ拓扑学结构； 晶化过程初期基本上未见到锐钛矿ＴｉＯ２生成． 随着晶化时间的推移，少量锐钛矿ＴｉＯ２ 开始出现． 样品的总钛含量在８ ｈ 附近达到最大值，Ｔｉ４ ＋ 基本上进入分子筛骨架． 值得一提的是，在晶化过程的第一小时内， ＭＦＩ拓扑学结构尚未充分形成（ 红外光谱中无１２２６ 和５５０ ｃｍ － １ 特征吸收峰） ， 但在９６０ ｃｍ － １ 处发现较弱的红外特征吸收峰，说明９６０ ｃｍ － １ 谱峰不是ＴＳ１ 分子筛所特有，它可能属于ＴＳ１ 分子筛的Ｓｉ—Ｏ—Ｔｉ 键，也可能属于ＳｉＯ２ＴｉＯ２ 共凝胶中的Ｓｉ—Ｏ—Ｔｉ 键．

The crystallization process of TS 1 has been investigated by using ICP AES, TEM, XRD, FT IR and FT Raman techniques. The results show that the large amorphous SiO 2 TiO 2 particles are visible at the beginning of crystallization, and the TS 1 crystals develop from the solution, preferentially on the outer surface of SiO 2 particles, which assist in the nucleation. The rapid crystallization of TS 1 is observed after 2～4 h and fully completed after 8 h at 170℃. TS 1 crystals grow with the crystallization time, and the simultaneous disappearance of amorphous SiO 2 particles is observed. The formation of TiO 2 anatase is absence at the beginning of the crystallization and the presence of very small amounts of TiO 2 is detected with the crystallization time (especially after 8 h). The maximum Ti content is found at crystallization time of 8 h. The IR band at 960 cm -1 of the samples is clearly observed at the first hour crystallization, which is not the characteristic of MFI structure (because another strong band at 555 cm -1 is not formed), showing that the IR band at 960 cm -1 is not only present in zeolites but also in the SiO 2 TiO 2 cogel.