Synthesis Of New Zn/Mg-containing Aluminophosphate Molecular Sieves

Aluminophosphate molecular sieves with regular nanopores and rich frameworks have been extensively used in catalysis, separation, adsorption, etc. In recent years, more and more heteroatoms could be doped into aluminophosphate molecular sieve frameworks. Thus the heteroatom-containing aluminophosphate molecular sieves with special channels and framework compositions have been prepared, which extends their applications. The synthesis of novel heteroatom-containing aluminophosphate molecular sieves has attracted more interest. In this thesis, the hydrothermal synthesis method has been used to synthesize novel Zn/Mg-containing aluminophsosphates by adjusting the kinds and amounts of structure-directing agents（SDA）. The influence of organic SDAs, gel compositions and crystallization conditions on the products has been discussed. The main achievements are as follows:（1） In Mg O-Al₂O₃-P₂O₅-PZ-H2 O synthetic system, a new magnesium-containing aluminophosphate with a zeolite-like structure |C4H12N2|[(Mg2Al6（PO4）8（H2O）4]（JU96） has been synthesized by using piperazine（PZ） as the SDA and Mg as the heteroatom. Its framework is constructed by the connection of Al O4/Mg O4（H2O）2 polyhedra and PO4 tetrahedra to form the ionic framework [Mg2Al6（PO4）8]2-, and protonated organic SDAs to achieve the charge balance. Its asymmetric unit contains eight crystallographically distinct framework positions: one Mg site, three Al sites and four P sites. Its framework possesses two-dimensional intersecting 8-ring channels. One 8-ring channel is running along the [100] direction,two 8-ring channels are running along the [001] direction. XRD, SEM, ICP, CHN and TG have been used for characterizing the stability and structure of JU96 and the known magnesium-containing aluminophosphates JU94 and JU95.（2） Using 1-（3-amino）-imidazole as the SDA and Zn as the heteroatom, three zinc-containing aluminophosphate molecular sieves have been synthesized in Zn O-Al₂O₃-P₂O₅-C6H11N3-H2 O synthetic system by adding different amount of structure-directing agent. XRD study indicates that they have zeolitic topologies of AEI, CHA and AFN, therefore they are named Zn-AEI, Zn-CHA and Zn-AFN, respectively. Their frameworks possess three-dimensional 8-ringchannels. ICP and CHN analyses show that the organic SDAs are intact kept in the structures of these three compounds.In conclusion, the influence of structure-directing agents for synthesizing heteroatom-containing aluminophosphate molecular sieves under the hydrothermal synthetic system has been mainly discussed in this thesis. A new Mg-containing aluminophosphate JU96 and three kinds of Zn-containing aluminophosphate molecular sieves have been successfully synthesized. Some synthetic rules for heteroatom-containing aluminumphosphate molecular sieves have been summarized through the experiments, which will be helpful for realizing directional synthesis of heteroatom-containing aluminumphosphate molecular sieves in the future.