合成原料、添加剂及模板剂对Ti-SiZSM-5分子筛合成的影响

INFLUENCE OF CHEAPER RAW MATERIALS, ADDITIVE AND TEMPLATE ON THE SYNTHESIS OF Ti-SiZSM-5 ZEOLITES

在廉价原料水热合成体系中 ,研究了硅源 (工业硅溶胶 )、模板剂 (无机钛源和廉价有机胺 )及杂质对 Ti-Si ZSM-5分子筛合成的影响。结果表明 ,硅溶胶聚合度低、胶粒小、 Na+ 含量低时 ,合成的 Ti-Si ZSM-5分子筛结晶度高、晶粒均匀 ,有利于 Ti进入分子筛骨架 ;用无机钛 Ti O(H2 O2 ) 2 + 溶液和用 Ti(OC4 H9) 4 有机钛源一样 ,可合成出高结晶度的 Ti-Si ZSM-5分子筛 ,Ti易进入分子筛骨架 ;在合成凝胶中加入 Na Cl可加快晶化速度 ,合成的分子筛粒度变小 ,但 Na Cl阻碍 Ti进入分子筛骨架 ,导致锐钛矿和 α-Si O2 的生成 ;合成中带入微量 Al3+ 可提高结晶度和晶化速度 ,在本实验合成范围内 (n(Si O2 ) / n(Al2 O3) >1 0 0 ) ,没有发现 Al3+影响钛进入分子筛骨架 ,但使合成的分子筛具有明显的酸性 ,易造成 H2 O2 分解和引起酸催化的副反应 ;不同廉价模板剂影响合成分子筛的晶貌和晶粒大小 ,NBA和 HDA既可合成出 Ti-Si ZSM-4 8,又可合成出 Ti-Si ZSM-5 ,合成后者的相区很窄。而混胺 (HDA+ TEAOH)模板剂有利于 Ti-Si ZSM-5分子筛的合成 ,合成相区较单胺为宽、重复性好。

The influence of cheaper raw materials,additives and templates on the synthesis of Ti SiZSM 5 zeolites were studied in detail. It showed that low degree of polymerized silica sol with low impurity content of Na + are beneficial to the synthesis of Ti SiZSM 5 zeolites. The incorporation of Ti in the zeolite framework was observed. Both titanium tetrabutoxide and TiO(H 2O 2) 2+ solutions were suitable to the synthesis of Ti SiZSM 5 zeolites. Additive (NaCl) added in the synthesis of Ti SiZSM 5 zeolites led to the increase of crystallization rate and decrease of crystalline particle size. NaCl may retard the incorporation of Ti in the lattice of zeolite. Al 3+ as the impurity is favorable to the synthesis of Ti SiZSM 5 zeolites,but it increases the acid strength of Ti SiZSM 5 zeolites which may cause inferior catalytic properties. Obviously,various templates caused effects on the crystalline phase,morphology and crystal size of synthesized Ti SiZSM 5 zeolite. Binary mixtures of HDA and TEAOH as the templates are beneficial to the synthesis of Ti SiZSM 5 zeolites.