Hollow SAPO-34 with an average particle size of ca .370 nm was synthesized by selective etching its precursor under the controlled alkaline condition. Subsequently, freestanding mixed matrix membranes were synthesized by UV-induced in-situ polymerization of the mixture of hollow SAPO-34, the fluorinated monomer , and the trifunctional cross-linker. The structure and the physical characteristic of hollow SAPO-34 and membranes were characterized by scan electron microscope, wide-angle X-ray diffraction, etc. The effect of the hollow SAPO-34 loading amount on the gas permeation-separation performance of mixed matrix membranes was investigated. The results showed that hollowing out SAPO-34 improved the N 2 /CH 4 sorption selectivity and converted the crystals from preferential adsorption of N 2 to preferential adsorption of CH 4 , the incorporation of hollow SAPO-34 into membranes increased the N 2 /CH 4 solubility selectivity and the permeability. The optimal membrane exhibited a 39-fold increase in N 2 permeability from 6.9 × 10 −13 to 2.7 × 10 −11 cm 3 (STP)cm·cm −2 ·s −1 ·Pa −1 at 0.2 MPa and 35 °C without the loss of N 2 /CH 4 permselectivity, which exceeded the 2008 Robeson upper bound.
Jie Gong,Fei Tong,Xiaobo Ji,Changfeng Zeng,Chongqing Wang,Yinong Lv,Lixiong Zhang
We herein report novel hollow SAPO-34 cubes with a hierarchical internal structure. They are prepared from dry gels containing gelatin by a vapor-phase transport method. Microscopic characterization reveals that the cubes are constructed by symmetrically packed four two-top-point truncated octahedrons encapsulated by dense crystalline shells, exhibiting a structure-in-structure formation. The cubes show either +-shaped or the butterfly like X-shaped black spots on their faces under light. Investigation of the formation process of the hollow SAPO-34 cubes demonstrates a surface to core crystal growth route, which has not been found in vapor-phase transport synthesis of zeolites. A possible formation mechanism is proposed.
危险品化学品经营许可证（带存储）