Effect of Si-ATP/CTAB ratio on crystal morphology, pore structure and adsorption performance of hierarchical (H) ZSM-11 zeolite

In this manuscript, the micro-mesoporous crystals with the properties of (H) ZSM-11 zeolites were successfully obtained via one-pot synthesis in the hydrothermal system by using acidified attapulgite (Si-ATP) and cetyltrimethylammonium bromide (CTAB) as a precursor source (PS) and structure-directing agent (SDA), respectively. The effect of Si-ATP/CTAB ratio on controlling the crystal morphology and hierarchical pore structure of products was systematically investigated. The synthesized materials were characterized with XPS, XRD, FTIR, NMR, SEM, TEM and N2 adsorption-desorption analysis. Results demonstrate that the products possess not only a classical zeolite framework but also an adjustable mesoporous structure accompanied with a variety of Si-ATP/CTAB ratios. Meanwhile Si-ATP/CTAB ratio has a well linear dependence with hierarchy factor (HF) in lower or higher ranges. The MFI crystal transforms gradually to the MEL-structure under the action of CTAB when Si-ATP/CTAB ratio increases to 80: 5. In addition, (H) ZSM-11 zeolite, this ratio of 80: 5, mesoporosity and adsorption capacity of MB molecules was significantly enhanced. Advanced adsorption performance is attributed to the abundance hydroxyl group and the generated mesoporosity of the zeolite surface under the participation of CTAB. The experimental data are well fitted to the Langmuir isotherm model, with a correlation coefficient of 0.9962. The excellent adsorption performance makes such hierarchically porous (H) ZSM-11 zeolites attractive for applications in the field of energy and environment.