Synthesis Of Porous Zeolites Materials Using Spirocyclic Quaternary Ammonium Salt And Germanium As Dual-Template

Zeolites are materials with unique properties such as uniform microporous structure,hydrophilic surface,high specific surface area,high thermal stability,adjustable framework composition and strong interaction with guest molecules,and are an important part of the modern chemical industry.Although the synthesis of new zeolites is currently very limited,the introduction of germanium(Ge)atoms has greatly promoted the development of zeolites with new framework structures and framework compositions.Because Ge atoms have a unique structure-directing role in promoting the formation of double three-membered ring(D3R)and double four-membered ring(D4R)building units and stabilizing these secondary building units.Thanks to the existence of these secondary building units,the formed silicogermanate zeolites usually have low skeletal density,large pore or extra-large pore structure.In addition,the structure-directing effect of organic template agents(organic structure-directing agents)strongly influences the synthesis of novel zeolites,expanding the application potential of zeolite based materials.Therefore,study on the synthesis of silicogermanate zeolites were carried out in this thesis using the spirocyclic quaternary ammonium salts and Ge atoms as dual-template.Firstly,silicogermanate UTL zeolite(denoted as[6,6]-UTL)and siliceous MTW zeolite(denoted as[6,6]-MTW)were successfully synthesized by hydrothermal synthesis with 7-azoniaspiro-[6,6]-tridecane as organic template agent in germanium-silicon or pure silicon system.The physicochemical properties of[6,6]-UTL zeolites were characterized and analyzed by various techniques.The effects of water content,germanium content and template agent content in the reaction mixture on the obtained samples were studied in detail.It was found that the above factors strongly affected the phase selectivity of UTL zeolite.The obtained sample in the presence of lower water content or higher template content changed from UTL to ISV structure,while with increased germanium content,the zeolite structure changed back to UTL.In addition,the structure and morphology of calcined[6,6]-UTL zeolite after acidic,neutral and alkaline treatment at high temperature were thoroughly studied.Secondly,silicogermanate zeolite with ISV structure(denoted as[5,5]-ISV and[5,6]-ISV,respectively)and siliceous zeolite with MTW structure(denoted as[5,5]-MTW and[5,6]-MTW,respectively)were successfully synthesized by hydrothermal synthesis method using 6-azonia-spiro-[5,5]-undecane or6-azoniaspiro-[5,6]-dodecane as organic template agent in germanium-silicon or pure silicon system.Similarly,the physicochemical properties of[5,5]-ISV and[5,6]-ISV zeolites were characterized and analyzed by various techniques,and the effects of rotational speed,crystallization time,water content,germanium content and template agent content on the obtained samples were studied in detail.Finally,four spirocyclic quaternary ammonium salts(5-azoniaspiro-[4,6]-undecane,6-azoniaspiro-[5,5]-undecane,6-azoniaspiro-[5,6]-dodecaneand7-azoniaspiro-[6,6]-tridecane,labeled as[4,6],[5,5],[5,6]and[6,6])with similar structure were used as organic templates to study the effects of Na~+on the synthesis of silicogermanate and siliceous zeolites.In addition,the specific effects of different Na~+concentration in the reaction mixture on the synthesis results were systematically studied by taking[5,6]and[6,6]as examples.