Zr-FSM-16中孔分子筛的合成及其对苯羟基化的催化性能

 以十六烷基三甲基溴化铵(CTMAB)为模板剂,合成出Zr-FSM-16中孔分子筛,并采用XRD,IR和BET等对分子筛进行了表征. 考察了Zr掺杂量和pH值等因素对分子筛结构的影响,并考察了合成出的Zr-FSM-16分子筛对苯羟基化反应的催化性能. 结果表明,Zr能有效地嵌入FSM-16的骨架之中,但Zr的嵌入对分子筛中孔结构的形成具有一定的不利影响,随着Zr嵌入量的增加,分子筛的长程有序度会下降; pH值对分子筛中孔结构的形成也具有十分显著的影响,在n(Si)/n(Zr)=40的条件下, pH＜12.5时,有序度随着pH值的升高而升高,pH＞12.5时则相反. 一般在n(Si)/n(Zr)＞40时,催化剂均能保持较好的六方晶体结构和较大的比表面积; n(Si)/n(Zr)＜20时,则较难形成中孔结构. Zr-FSM-16对于苯的羟基化反应具有良好的催化性能,催化活性和选择性均随Zr嵌入量的增加而升高,n(Si)/n(Zr)=40时,苯酚的选择性可达65%以上.

Synthesis of Zr-FSM-16 Mesoporous Zeolite and Its Catalytic Performance for Hydroxylation of Benzene

The Zr FSM 16 mesoporous zeolite was synthesized by using cetyltrimethyl ammonium bromide (CTMAB) as a template, and the samples were characterized by XRD, IR and N 2 adsorption. Effects of some synthetic factors, such as the zirconium amount and pH value, on the formation of meso structure were investigated. The catalytic performance of Zr FSM 16 for hydroxylation of benzene was studied. The zirconium could be incorporated into the frame of FSM 16 zeolite, but it exerted a negative effect to the meso structure of Zr FSM 16 zeolite, the long range order of Zr FSM 16 decreased with the increase of zirconium amount. The pH value affected the formation of Zr FSM 16 zeolite remarkably. At n (Si) / n (Zr) =40, the order of Zr FSM 16 was enhanced with the increase of pH value when pH<12 5, and a reverse result was obtained when pH>12 5. The Zr FSM 16 zeolite showed higher activity for hydroxylation of benzene, and both the activity and selectivity increased with the increase of zirconium amount. The selectivity for phenol of Zr FSM 16 with n (Si) / n (Zr) =40 could reach 65%. Generally, when n (Si) / n (Zr) >40, the catalyst possessed good mesoporous structure and high surface area, and it was difficult to form meso structure when n (Si) / n (Zr) <40. The variation of structure and surface area verified the incorporation of Zr into the framework of FSM 16 zeolite.