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The Syntheses and Structures of M(Ⅱ)APO Zeolites

Author: ShaoLang
Tutor: YuJiHong; XuRuRen
School: Jilin University
Course: Inorganic Chemistry
Keywords: Zeolites Aluminophsphates Divalent-metal ions Hydrothermal Synthesis Structures
CLC: O611.4
Type: PhD thesis
Year: 2013
Downloads: 71
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Abstract


Over the course of the past30years, aluminophsphates molecular sieves（denoted as AlPOs） have become an important member of zeolite family. Metal ionscan be introduced into the frameworks of AlPOs to form a metal-containing AlPOs（named as M（Ⅱ）APOs）. The introduction of the metal ions, not only gives theM（Ⅱ）APOs excellent catalytic and optical properties, but also can induce novelzeolite topologies. Therefore, the synthesis of M（Ⅱ）APOs has attracted extensiveattention. In this thesis, we have synthesized a series of M（Ⅱ）APOs, and theirstructures and properties have been characterized in detail. Meanwhile, we studiedthe effect of M2+ions （M=Co, Zn, Mg and Mn） on the final products of M（Ⅱ）APOsin the triethylene diamine system. The main results in this thesis are as follows:1. Two divalent-metal-containing aluminophosphates: M（Ⅱ）APO-CJ62;（M=Co,Zn）, have been hydrothermally synthesized by using N-methylpiperazine as thestructure directing agent. Both of these compounds exhibit a new zeolite frameworktopology, which has been assigned a three-letter code JSW by international zeoliteassociation （IZA）. All the M/Al and P atoms are tetrahedrally coordinated andalternately connected to each other through bridging O atoms. This new zeoliteframework contains1-dimensional8-ring channels running along the [010] direction.The M2+ions in M（Ⅱ）APO-CJ62selectively occupy two of the three possiblecrystallographically distinct positions. Inductively coupled plasma （ICP） analysisshows that the molar ratio of M:Al in M（Ⅱ）APO-CJ62is1:2. Structural optimizationand distortion analysis reveal that serious distortions exist in Al（1） andAl（2）-centered tetrahedra in the hypothetical framework of AlPO-CJ62. To releasethe stress generated at these two sites, incorporation of M2+ions appears to benecessary to form flexible M-centered tetrahedra instead of rigid Al-centeredtetrahedra. The introduction of M2+becomes a favorable factor for the formation ofM（Ⅱ）APO-CJ62. A pure aluminophosphate analogue of M（Ⅱ）APO-CJ62, denoted as AlPO-CJ62, has not been obtained in experiment so far.2. Four M2+-containing aluminophosphate molecular sieves, M（Ⅱ）APO-CGFand M（Ⅱ）APO-OSI （M=Co and Zn） have been synthesized hydrothermally in thepresence of DABCO as the SDA. By varying the types and the amounts of M2+ions,we have further studied the role of M2+ions in the synthesis of M（Ⅱ）APOs. ElevenM（Ⅱ）APOs with the CGF, OSI, AFN, SOD, LEV and AFI topologies are obtained.The result shows that the types of M2+ions play an important role in directing thefinal crystalline products, due to the different coordination geometry of M2+ions. Inaddition, more than one structure can be produced by altering the amounts of M2+ions. Structural optimization and bond angle variances analysis reveal that thedistortions of AlO4tetrahedra in the structures are AlPO-OSI 2+ions needed tostabilize the whole framework structure. Thus, the introduction of M2+ions becomesa favorable factor for the phase selectivity of M（Ⅱ）APOs.3. Three divalent-metal-containing open-framework aluminophosphates,designated M（Ⅱ）APO-CJ50,（M=Mg, Mn and Fe）, have been hydrothermallysynthesized by using2,2’（Ethylenedioxy）bis（ethylamine） as the template. Singlecrystal and powder X-ray diffraction analyses show that their structures are similar tothose of trivalent-metal-containing aluminophosphates M（ⅡI）APO-CJ50synthesizedby imidazole. The differences between M（Ⅱ）APO-CJ50and M（ⅡI）APO-CJ50are:hetero-metal-atoms in M（Ⅱ）APO-CJ50have lower oxidation states owing to theusage of ether amine; in M（Ⅱ）APO-CJ50, hetero-metal-atoms are coordinated to thetwo O atoms in each ether amine molecule, whereas in M（ⅡI）APO-CJ50hetero-metal-atoms are coordinated to pairs of imidazole molecules through single Natoms. Moreover, magnetic measurements reveal that the hetero-metal-atoms inM（Ⅱ）APO-CJ50are high-spin whereas those in M（ⅡI）APO-CJ50are low-spin owingto the differences in oxidation states and ligand molecules.

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CLC: > Mathematical sciences and chemical > Chemistry > Inorganic Chemistry > Chemical elements and inorganic compounds > Inorganic synthetic chemistry
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