晶化温度对V–MCM–41分子筛介孔结构、形貌及性能影响

Effect of Crystallization Temperature on Mesoporous Structure, Morphology and Performance of V–MCM–41 Mesoporous Molecular Sieve

采用原位合成水热法制备了掺杂型V–MCM–41介孔分子筛。采用X射线衍射、Fourier变换红外光谱和扫描电子显微镜等研究了晶化温度对V–MCM–41分子筛的介孔结构、形貌和催化性能的影响。结果表明,晶化温度过低或过高时,V–MCM–41介孔分子筛有序度较差;在110℃晶化温度下,形成高度有序的六方相介孔结构的介孔分子筛。该分子筛具有球形形貌特征,经水热处理8 d后仍具有介孔特征,比表面积保留率高达80.7%。在苯乙烯催化氧化反应中,V–MCM–41介孔分子筛表现出较优的对苯乙烯催化氧化性能。

Molecular sieve V–MCM–41 with mesoporous structure and good hydrothermal stability was synthesized through in–situ hydrothermal method. Effect of the crystallization temperature on the materials were studied using X–ray diffraction, Fourier transformed infrared spectroscopy and scanning electron microscopy. The results show that the order of V–MCM–41 was poor when the crystallization at extra–low or high temperature. In particular, sample prepared at 110℃ for 48 h presents a complete spherical morphology with the ordered hexagonal structure, uniform pore size distribution and large surface area, compared to other samples. Meanwhile, the prepared materials retained the most ordered mesoporous structure and highest texture parameters, and the surface area retention rate of V–MCM–41 was 80.7% even after hydrothermal treatment for 8 d in boiling water. It was due to the polymer silica form resulted in the hydrolyzation and polymerization of Na2O·3.3SiO2 silica sources, which the polymer silica would make strong the reciprocity between the surfactant and silica source. In styrene catalytic oxidation, the catalytic oxidation of styrene showed better catalytic performance.