Syntheses, Structures And Properties Of Novel Layered Aluminophosphates

Open-framework aluminophosphates constitute an important class of inorganic microporousmaterials, and have widespread prospect of applications in the field of catalysis, separation,adsorption and electrochemistry. Since1982U. C. C. reported aluminophosphate molecularsieves for the first time, a large number of aluminophosphates have been found with diversestoichiometric ratios and structure types after more than thirty years of development. Accordingto the Al/P stoichiometric ratio, open-framework aluminophosphate compounds can be dividedinto1:1，1:2，1:3，2:3，3:4，4:5，6:7，12:13and13:18. They also can be classified as0-D clusters,1-D chains,2-D layers and3-D open frameworks based on the structure. The2-D layeredaluminophosphates not only show extremely rich types of framework, but also can be connectedinto three-dimensional structures due to the extensive P—OH and P=O terminal groups. Thegood hydrophilic property and abundant presence of hydrogen bonds imply potential applicationvalue in proton conduction field of layered aluminophosphates. The incorperation of heteroatomsespecially transition elements to this system brings Br nsted acid sites and catalytic activecenters, and can also develop new types of aluminophosphate sieves. On the other hand, chiralinorganic microporous compounds have wide applications in chiral separation andenantioselective catalysis, but how to synthesize a chiral framework compound is still a bigchallenge.In this thesis, taking layered aluminophosphates as the subject, we synthesize a series ofnovel layered aluminophosphate materials under solvothermal conditions, and study theirstructures and properties, such as protion conducting. We further investigate the substitution,co-template effect and chiral induction aspects. The main achievements are summerized asfollows: 1. Using N, N-dimethylbenzylamine as the template, we synthesize a novel two-dimensionalaluminophosphate (denoted as AlPO-CJ70) in the tetraethylene glycol-water system, whichshows a new type of layered structure. The chemical formula of AlPO-CJ70is[C9H14N]8[H2O]4·[Al8P12O48H4]. Parts of the Al atoms in the framework can be substituted by Co,Fe, Zn, Mn and Mg. The framework of AlPO-CJ70is made of strict alternation of AlO4and PO4tetrahedra, and consists of a novel4×6×8network. The coordination modes of T (Al or P) atomsin AlPO-CJ70are AlO4b, PO3bO1tand PO2bO2t(b: bridging, t: terminal). AlPO-CJ70shows8-ring straight channels along the [100] direction and the anioic Al2P3O123-layers are stacked inan AAAA sequence. All of the N, N-dimethylbenzylamine molecules are protonated to balancethe framework charge. Parts of the Al atoms can be substituted by Co, Fe, Zn, Mn and Mg.FeAlPO-CJ70shows antiferromagnetic interaction between Fe atoms in the framework. Protonconduction measurements on AlPO-CJ70show a better proton conduction property than most ofthe aluminosilicate zeolites. The A.C. proton conductivity value of AlPO-CJ70in water is4.20×10-4S·cm-1at25℃and increases to9.25×10-4S·cm-1at80℃. The proton conducting processin AlPO-CJ70powder immersed in water follws a Grotthuss-like mechanism.2. Using diethylamine and1,2-diaminopropane as the co-template, we synthesize two2-dimensional aluminophosphates (denoted as CoAlPO-CJ71a and AlPO-CJ71b) in thetetraethylene glycol-water system. The chemical fomula of CoAlPO-CJ71a is[C4H11N]0.77[C4H12N]0.23[C3H12N2]2[H3O]2·[Co0.23Al5.77P8O32] and that of AlPO-CJ71b is[C4H12N]3[C3H12N2]2[H3O]5·[Al12P16O64], both with an M/P ratio of3/4(M=Al or Al+Co).The synthesis regularies of aluminophosphates in the co-template system are studied. Thesubstitution effect of heteroatoms and the co-template effects are also analyzed. The decisiverole of co-template effect on the formation of aluminophosphate framework has been provedthrough theoretical calculation.3. Two new2D layered aluminophosphates [R-C8H12N]8[H2O]2·[Al8P12O48H4] and[S-C8H12N]8[H2O]2·[Al8P12O48H4](denoted as AlPO-CJ72-R and AlPO-CJ72-S, respectively)have been synthesized by using R-or S-α-methylbenzylamine as the templates undersolvothermal system. The frameworks of AlPO-CJ72-R and AlPO-CJ72-S exhibit the mirrorsymmetric feature. The inorganic frameworks of those both consist of4×6networks, and the [4.62] structure units in their frameworks form chains along c direction, which are connectedwith each other by6-rings. Through the structures analysis we find that the terminal O atoms inP=O in the frameworks and the protonated templates form chiral H-bond chains, which areassociated with the frameworks by P=O bonds. The chirality of templates is transferred to theinorganic frameworks of AlPO-CJ72-R and AlPO-CJ72-S by self-assemble during the synthesisprocesses, which induces helical chains and chiral frameworks.