ITQ-24分子筛的合成及催化性能研究

SYNTHESIS AND CATALYTIC PERFORMANCE OF ITQ-24 ZEOLITE

以1,1′-[1,4-苯双亚甲基]双[1-甲基吡咯烷]氢氧化物为有机结构导向剂(OSDA)制备了ITQ-24分子筛,系统考察了GeO_(2)含量、OSDA用量、HF含量、晶化温度、搅拌速率对ITQ-24分子筛晶化的影响。并采用X射线衍射(XRD)、扫描电子显微镜(SEM)、氨程序升温脱附(NH 3-TPD)和吡啶吸附红外光谱(Py-IR)等方法对晶化产物进行了表征。结果表明:适合ITQ-24分子筛晶化的初始凝胶组成为n(SiO_(2))∶n(GeO_(2))∶n(OSDA)∶n(H_(2)O)=1∶(0.2~0.5)∶0.3∶(5~20),晶化条件为动态、170℃;所制得的ITQ-24分子筛具有较高的水热稳定性,含有较多的弱酸和Lewis酸位。将该分子筛应用于环己酮氧化制备ε-己内酯反应中,在80℃最佳反应温度下,环己酮的转化率为22.5%,ε-己内酯的选择性可达到54.5%。

ITQ-24 zeolite was synthesized using 1,1′-[1,4-phenylenebis(methylene)]bis[1-methyl pyrrolidinium]hydroxide as organic structure-directing agent(OSDA).The effects of Ge content,OSDA amount,HF content,crystallization temperature,and stirring speed on the crystallization of ITQ-24 zeolite were investigated,respectively.X-ray diffraction(XRD),scanning electron microscope(SEM),temperature-programmed desorption of NH 3(NH 3-TPD)and Fourier transform infrared spectroscopy of pyridine adsorption(Py-IR)methods were carried out to characterize the obtained zeolites.The suitable molar composition n(SiO_(2))∶n(GeO_(2))∶n(OSDA)∶n(H_(2)O)for the crystallization of ITQ-24 zeolite is 1∶(0.2-0.5)∶0.3∶(5-20),and the optimum temperature is 170℃under dynamic condition.The ITQ-24 zeolite has high hydrothermal stability and contains lots of weak and Lewis acid sites.In the oxidation reaction of cyclohexanone toε-caprolactone,using ITQ-24 as catalyst,theε-caprolactone selectivity reached 54.5%with 22.5%cyclohexanone conversion under the optimum temperature of 80℃.