氨基酸辅助构建多级孔TS-1分子筛应用于苯羟基化反应

Amino acid-assisted construction of hierarchical TS-1 zeolite for hydroxylation of benzene

多级孔分子筛因具有良好的水热稳定性、较大的孔体积和短的扩散距离而倍受关注。以L-赖氨酸为介孔造孔剂,采用低、高温两步晶化法可制备多级孔结构的TS-1分子筛,该方法首先通过低温晶化增加晶核数量,再在高温晶化中利用L-赖氨酸的限域作用使晶粒尺寸均一,最终制得形貌规则、高结晶度的多级孔TS-1分子筛。该分子筛的多级孔道结构有利于减小反应物和产物的扩散阻力,增大扩散速率,提高催化性能,其在苯直接氧化制苯酚反应中,苯转化率高达38.6%,苯酚收率为26.5%。

Hierarchical zeolite has attracted wide attention because of its good hydrothermal stability,large pore volume and short diffusion distance.Here,using L-lysine as a mesoporous pore-forming agent,hierarchical TS-1 zeolite was synthesized by two-step crystallization at low and high temperature.In this method,the number of crystal nuclei was increased by low-temperature crystallization,and then the crystal size was uniform by the confinement effect of L-lysine during high-temperature crystallization.Finally,the hierarchical TS-1 zeolite with regular morphology and high crystallinity was prepared.The mesoporous pore in the hierarchical TS-1 zeolite is beneficial to reduce the diffusion resistance of reactants and products,increase the diffusion rate,and improve the catalytic performance.In the direct oxidation of benzene to phenol,the conversion of benzene is as high as 38.6%,and the yield of phenol is 26.5%.