氩吸附法研究多级孔分子筛的孔结构

采用不同方法分别制备了双介孔分子筛、介微孔分子筛及介孔沸石材料,利用氩吸附法并结合XRD技术表征了多级孔分子筛的孔结构。探讨了适用于多级孔分子筛的孔径分布计算方法,揭示了不同类型吸附等温线与孔径分布、孔型及孔容等之间的关系。研究表明,对于多级孔分子筛、微孔和介孔的孔径分布分别用SF法和BJH法计算较适宜,全孔分析可用NLDFT法计算。通过对TS-1介孔沸石的孔结构分析发现, TPAOH 在改性制备介孔TS-1的过程中起到了生成介孔及促进二次晶化的双重作用。

Pore structures of hierarchical porous molecular sieves observed by Ar adsorption

Dual mesoporous, micro-mesoporous and mesoporous molecular sieves were prepared and their pore structures were characterized by Ar adsorption and X-ray diffraction (XRD). The calculation methods of pore size distribution for the hierarchical porous molecular sieves were studied, to reveal the relationships among the adsorption-desorption isotherm, pore size distribution, pore shape and pore volume. The results showed that SF and BJH methods are reliable for microporous and mesoporous pores of the hierarchical porous molecular sieves, respectively, whereas NLDFT method is appropriate to calculate the full range pore size distribution. For the synthesis of mesoporous TS-1 zeolite, TPAOH promotes not only the generation of mesopores, but also the secondary crystallization.