摘要
以工业级正十六胺为模板剂,采用水热法合成了不同Ti含量的Ti-HMS分子筛,并用六甲基二硅氮烷对其进行气相硅烷化。采用X射线衍射、N2吸附、傅里叶变换红外光谱、交叉极化/魔角旋转29Si核磁共振、紫外-可见光谱和电感耦合等离子体原子发射光谱(ICP-AES)对试样进行了表征。以过氧化氢异丙苯(CHP)为氧化剂,用环己烯的环氧化反应考察了Ti-HMS分子筛的催化性能。实验结果表明,合成的Ti-HMS分子筛试样具有典型的六方介孔特征,Ti主要以骨架四配位状态存在,硅烷化显著增加了Ti-HMS分子筛表面的疏水性。以不同Ti含量的Ti-HMS分子筛为催化剂,产物环氧环己烷(CHO)的选择性都超过90%,以凝胶中n(Si)∶n(Ti)=50时所合成的Ti-HMS分子筛为催化剂CHP转化率最高(75.9%)。以硅烷化后的Ti-HMS分子筛为催化剂,CHP转化率和CHO选择性有较大幅度的提高,分别达到80.3%和97.8%。
Ti -HMS molecular sieves with different Ti contents were synthesized hydrothermally with industrial hexadecylamine as template and subsequently silylated with hexamethyldisilazane in vapor- phase. The molecular sieves were characterized by means of XRD, N2 -adsorption, FFIR, ^29Si CP/MIN NMR, UV - Vis and ICP - AES. The catalytic performance of molecular sieves was evaluated by epoxidation of cyclohexene with cumene hydroperoxide （CHP） as oxidant. Ti - HMS molecular sieve is hexagonal mesoporous in structure. Most of titanium species exist in tetra - coordinated state. The silylation improves hydrophobicity of Ti - HMS molecular sieve surface. Ti - HMS molecular sieves with different Ti contents all show high selectivity to cyclohexene oxide （more than 90% ）. Ti -HMS molecular sieve with n （Si） ： n （Ti） 50 in gel exhibits the highest CHP conversion （75.9%）. Both conversion of CHP and selectivity to cyclohexene oxide increase after silylation, reach 80.3 % and 97.8 %, respectively .
出处
《石油化工》
EI
CAS
CSCD
北大核心
2007年第5期441-446,共6页
Petrochemical Technology
基金
国家重点基础研究发展计划(973)项目(2003CB615805)
