Factors Affecting The Structure-directing Effect In The Synthesis Of Open-framework Aluminophosphates

Zeolites and related microporous crystalline materials have been widely used in chemical industry such as catalysis,ion exchange,separation,and adsorption.In the synthesis of such materials,structure-directing effect plays a critical role.Great efforts have been made to understand the nature or orgin of the structure-directing effect.However,the method by which the structure-directing agent works during the synthetic process is still not clear and the knowledge of the nature of the structure-directing effect is still very limited due to the extremely complex of the synthesis systems and the limited physicial and time resolution of the current characterization techniques.In 1982,Wilson and co-workers reported a new class of microporous crystalline aluminophosphates,Al PO4-n?n denotes a structure type?,with neutral zeolite-like open-frameworks,a high degree of structural diversity,and a wide range of pore sizes and volumes.Aluminophosphates have become a large family of crystalline open-framework materials,which display rich variety of structures,including neutral zeolite-like open-frameworks;a range of anionic open-frameworks with 0D cluster,1D chain,2D layer,and 3D framework structures;and a rich variety of stoichiometries.In this dissertation,we investigated the factors affecting the structure-directing effect of amines in the synthesis of open-framework aluminophosphates.The main results are summarized as follows:1.Three layered aluminophosphates(UiO-15,APDAP₁₂-150,and APDAP-150)with the same topology were crystallized from an initial mixture with a composition of Al2O3 : 1.5 P2O5 : 5.5 R : 227 H2 O,where R is ethylenediamine,1,2-diaminopropane,and 1,3-diaminopropane,respectively.The crystallization processes of Ui O-15,APDAP₁₂-150,and APDAP-150 were investigated using solid-state NMR in combination with XRD and other characterization techniques.The evolution of the coordination states of Al and P in the solid products was monitored,and the possible starting points of crystallization?core units?of Ui O-15,APDAP₁₂-150,and APDAP-150 were obtained and analyzed.The formation of atrimer,hexamer,monomer of PO4,and nonamer containing two three-membered rings;the formation of a hexamer and pentamer;and the formation of an Al O6 monomer and pentamer containing a 3-ring are critical for the start of crystallization of Ui O-15,APDAP₁₂-150,and APDAP-150,respectively.The crystal water played a co-structure-directing role in the formation of APDAP-150.2.Three aluminophosphates(APDAP₁₂-150,UiO-18,and Ui O-26)were crystallized from an initial mixture with a composition of Al2O3 : P2O5 : 5.0 R : 277 H2 O at 180 or 200 °C in the presence of 1,2-diaminopropane or 1,3-diaminopropane.The crystallization processes of APDAP₁₂-150,Ui O-18,and Ui O-26 were investigated using solid-state NMR in combination with XRD and other characterization techniques.The evolution of the coordination states of Al and P in the solid products was monitored,and the possible starting points of crystallization?core units?of APDAP₁₂-150,Ui O-18,and Ui O-26 were obtained and analyzed.3.By heating the initial mixture with the molar composition of Al2O3 : 6.0 P2O5 : n 1,2-diaminopropane : 139 H2 O at 180 °C,a new three-dimensional open-framework aluminophosphate compound 1 and a two-dimensional layered aluminophosphate APDAP₁₂-150 were obtained at n=5.5 and n=7.5,respectively.The framework topology of compound 1 is the same to that of Al PO-CJ31,a three-dimensional open-framework aluminophosphate directed by the template of diethylenetriamine.By combing the powder X-ray diffraction analysis,elemental analysis?CHN?,and TG/DTA,we determined the composition of compound 1 and found the co-templating effect of protonated water.4.Aluminophosphate molecular sieves Al PO4-21 and Al PO4-11 were crystallized from an initial mixture with a composition of Al2O3 : P2O5 : R : 139 H2 O in the presence of dimethylamine and diethylamine,respectively.The crystallization processes of Al PO4-21 and Al PO4-11 were investigated using solid-state NMR in combination with XRD and other characterization techniques,and the structure-directing effect of dimethylamine and diethylamine were investigated during the crystallization of Al PO4-21 and Al PO4-11.