铵盐对TS-1分子筛合成过程中钛物种分布的影响  

Effect of ammonium salt on the distribution of titanium species in the synthesis of TS-1 zeolites

作　　者：佘豪豪 丁国强 李显清 王洪星 曹东波[1,3] 朱玉雷 李永旺[1,3] SHE Hao-hao;DING Guo-qiang;LI Xian-qing;WANG Hong-xing;CAO Dong-bo;ZHU Yu-lei;LI Yong-wang(State Key Laboratory of Coal Conversion,Institute of Coal Chemistry,Chinese Academy of Sciences,Taiyuan 030001,China;University of Chinese Academy of Sciences,Beijing 100049,China;Synfuels China Co.Ltd,Beijing 101407,China)

机构地区：[1]中国科学院山西煤炭化学研究所煤转化国家重点实验室,山西太原030001 [2]中国科学院大学,北京100049 [3]中科合成油技术有限公司,北京101407

出　　处：《燃料化学学报》2021年第8期1148-1160,共13页Journal of Fuel Chemistry and Technology

基　　金：国家重点研发计划(2018YFB1501602)资助。

摘　　要：以(NH)_(4)SO_(4)作为晶化调节剂,通过调节铵盐添加量,合成出了不同钛物种分布的TS-1-X系列分子筛(X为铵盐与SiO_(2)的物质的量比)。通过ICP-AES、FT-IR、UV-vis、UV-Raman等表征对TS-1-X系列分子筛中钛物种分布进行了系统的研究。以1-己烯环氧化为探针反应,考查了TS-1-X分子筛的催化性能。研究结果表明,适量铵盐不仅有利于钛从液相向固相富集,促进Ti元素进入MFI骨架结构,还有利于抑制晶粒过快生长,得到晶粒粒径小且分布均匀的TS-1分子筛;而过量的(NH)_(4)SO_(4)反而利于锐钛矿TiO_(2)、无定型钛等非骨架钛物种的形成,同时促进晶粒过快生长得到大晶粒TS-1分子筛。最后,当n((NH_(4))_(2)SO_(4))/n(SiO_(2))=0.2时合成出反应性能最佳的骨架富钛TS-1,其对1-己烯转化率高达42%,同时H2O_(2)的有效利用率为81.8%。此外,通过实验和表征考察了铵盐中各组分对TS-1性质的影响,发现铵盐通过自身的阴离子以及对pH值的改变,对TS-1晶化体系进行调节。Titanium silicalite(TS-1)zeolites with different distribution of Ti species were synthesized through altering different amounts of(NH_(4))_(2)SO_(4) as crystallization-mediating agent.The distribution of titanium species of TS-1-X samples(X represents the molar ratio of(NH_(4))_(2)SO_(4) to SiO_(2))was systematically investigated via ICP-AES,FT-IR,UV-Vis,UV-Raman and other techniques.The TS-1-X zeolite samples were applied in the epoxidation of 1-hexene reaction.It was found that the appropriate amount of ammonium salt not only facilitated the enrichment of titanium species from liquid phase to solid phase and promoted the incorporation of Ti into the MFI skeleton,but also resulted in the formation of uniformly small TS-1 crystals due to the inhibition of rapid growth of crystals.However,much more amounts of(NH_(4))_(2)SO_(4) led to the formation of extra-framework Ti,including anatase TiO_(2) and amorphous Ti species.Meanwhile it promoted the rapid growth of grain resulting in larger TS-1 crystals.Ti-rich TS-1 sample synthesized with molar ratio of(NH_(4))_(2)SO_(4) to SiO_(2) of 0.2 exhibited higher conversion of 1-hexene(42%)and effective utilization of H2O_(2)(81.8%).In addition,the effect of ammonium salt’s composition on the properties of TS-1 was investigated by experiments and characterizations.It was found that ammonium salt could regulate the process of crystallization through its own anion and changing PH of the synthesis gel.

关 键 词：Α-烯烃 钛硅分子筛 1-己烯 环氧化 

分 类 号：O643[理学—物理化学]