The Syntheses And Properties Of Heteroatom-substituted Aluminophosphate Zeolites And 2-D Layered Aluminophosphate Compounds

Zeolites,as an important member of inorganic porous crystalline materials,play a significant role in the petrochemical industry and environmental area,because of their excellent performances in adsorption,separation and catalysis.Following traditional aluminosilicate zeolites,aluminophosphate zeolites with various topologies of structures have been developed.Especially,the introduction of heteroatoms endows them with various topologies and excellent properties of catalysis and separation,etc.The isomorphous substitution of heteroatoms not only avoids the decrease of adsorption amount caused by the occupation of exchanged species in the channels,but also brings extra-framework protons and affects the formation of H-bonds in the structure.With the development of synthetic techniques,various aluminophosphate open frameworks have been synthesized,including three-dimensional open framework structures,twodimensional layered structures and one-dimensional chain structures.In the structure of low-dimensional aluminophosphate open frameworks,the presence of the organic species,protons and the water molecules provides an efficient proton transport pathway and high proton conductivity for the materials.This thesis focuses on the adsorption and proton conductivity of aluminophosphates and 2D layered aluminophosphates,particularly,the effects of isomorphous substitution of heteroatoms on these two properties.This work will provide some guidance for the design and synthesis of aluminophosphate zeolites and two-dimensional layered openframework materials with superior properties.The main results are as follows: 1.Mg,Co-substituted aluminophosphate zeolites with ERI topology（denoted as Mg APO-ERI and Co APO-ERI）have been synthesized under hydrothermal conditions by using N,N,N’,N’-tetramethyl-1,6-hexanediamine（TMHDA）as organic template.Their CO₂ adsorption properties are investigated as compared with that of pure aluminophosphate counterpart Al PO-ERI.Co APO-ERI shows the highest CO₂ uptake of 57.3 cm³ g^-1（273 K and 1 bar）and the highest isosteric heat of 39.0 k J mol^-1 among the three samples.Importantly,the incorporation of Mg²⁺ and Co²⁺ ions in the framework of AlPO-ERI can greatly improve the adsorption selectivities of CO₂ over CH₄ and N₂.Calculations show that the introduction of heteroatoms leads to an increase in adsorption enthalpy which affects the amount of adsorption of the sample.In addition,the separation ratio of CO₂/CH₄,CO₂/N₂ and transient breakthrough simulations have also been investigated which further proves the advantages of the introduction of heteroatoms for separations.These results demonstrate that isomorphous heteroatom substitutions play a key role in enhancing CO₂ adsorption and separation abilities in aluminophosphate zeolites.2.Taking advantage of the charge-transfer property of imidazolium,high protonconducting aluminophosphates with AFI topology have been synthesized by using 1,2-dimethylimidazole.Particularly,the conductivity could be further improved by 4 times reaching 2.55 × 10^-3Scm^-1 at 368 K and 98% humidity after introducing Mgsubstitution,which shows excellent proformance among zeolite materials.These results show that the introduction of heteroatoms brings active protons to the protonconducting pathway,which can improve the conductivity by increasing the number of carriers and reducing the activation energy for conduction by shortening the distance between adjacent hopping sites.3.A series of heteroatom-substituted aluminophosphate zeolites analogues MAPOLAU（M = Mn,Co,Zn）have been synthesized in solvothermal conditions by using imidazole as templet.Under the premise of the same heteroatom doping amount,the influence of doping atom species on proton conduction performance is systematically studied.Zn APO-LAU shows the highest conductivity among the three samples at 98% humidity,which reaches 6.1 × 10^-4Scm^-1 at 298 K and 6.1 × 10^-4Scm^-1 at 323 K.In addition,the performance of Zn-substituted LAU is better than Co-and Mn-substituted LAU with same substitution amount.4.The proton conductivity of 2-D layered aluminophosphate [N₂C₃H₅]₂[Al₃P₄O₁6H] templated by imidazole has been studied.It shows high conductivity of 3.3 × 10^-4Scm^-1 at 298 K and 1.76 × 10^-3Scm^-1 at 368 K at 98% humidity.Besides,the material maintains high stability after testing in humidity and high-temperature conditions.5.Homochiral layered aluminophosphates [R-C₈H₁2N]₈[H₂O]₂·[Al₈P₁2O₄8H₄] and [SC₈H₁2N]₈[H₂O]₂·[Al₈P₁2O₄8H₄]（denoted as AlPO-CJ72-R and AlPO-CJ72-S）with mirror symmetric features have been separately synthesized by using R-（+）-α-methylbenzylamine and S-（-）-α-methylbenzylamine as templet.Especially,they have been obtained as an optical pure open-framework material for the first time.The organic molecule can affect the connection of AlO₄,PO₃（=O）or PO₂（=O）（OH）tetrahedron by forming helical H-bond chains and transferring the chirality in the framework.On account of the abundant H-bond chains,Al PO-CJ72 exhibits high conduction of 3.01 ×10^-3Scm^-1 at 298 K and 98% humidity.