Structure-Directing Role of Molecules Containing Benzyl Rings in the Synthesis of a Large-Pore Aluminophosphate Molecular Sieve: An Experimental and Computational Study (original) (raw)
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Ionothermal Synthesis of an Aluminophosphate Molecular Sieve with 20-Ring Pore Openings
Angewandte Chemie International Edition, 2010
Crystalline porous materials with large or extralarge pores continue to be of particular significance in both industry and academia for their potential applications in shape-selective catalysis and adsorption/separation. Of these zeolitic materials, especially aluminosilicate-and aluminophosphate-based molecular sieves are of prime interest because of their high stability associated with their widespread use in many established process and emerging applications. The materials VPI-5 (VFI framework type, 18-ring) and UTD-1 (DON framework type, 14-ring) were the first extra-large pore (pores constructed of more than 12 T atoms) aluminophosphate and aluminosilicate materials discovered. The oxide frameworks are built up by corner-sharing [AlO 4 ] and [PO 4 ] tetrahedra as well as [AlO 4 ] and [SiO 4 ] tetrahedra. In the search for materials with even larger pores, an anionic open-framework aluminophosphate JDF-20 (20-ring) was reported; however, it could not be classified as a zeolite because its framework (with an Al/P ratio of 5:6) is unstable upon removal of the occluded protonated templates by calcination. Larger pore openings were also achieved using Ge or Ga as the framework T atom in a high amount, for example in ECR-34 (ETR framework type, 18-ring), ITQ-33 (18-ring), cloverite (-CLO framework type, 20ring), and ITQ-37 (30-ring). In this context, the use of Ge or Ga as framework atoms as well as fluoride has been found to facilitate the formation of a double four-ring (D4R) unit. This is in agreement with the prediction by Brunner and Meier that structures with extra-large pores should contain a large number of three-and four-membered rings. Ionothermal synthesis, in which ionic liquids act as both the solvent and template, is a novel method that has attracted great interest in the synthesis of zeolitic and other porous materials. Besides the advantage of experimenting at ambient pressure, ionic liquids offer different chemistry and structural variety associated with the use of additional amines as structure-directing agents (SDA), and therefore open up new vistas for the synthesis of new porous materials. Herein, we report the ionothermal synthesis of the first aluminophosphate molecular sieve with 20-ring pore openings, denoted as DNL-1 (Dalian National Laboratory Number 1). This molecular sieve was confirmed as a structural analogue to the gallophosphate molecular sieve cloverite by using a combination of Rietveld refinement of powder X-ray diffraction (PXRD) data and NMR analysis. Moreover, in comparison to cloverite, DNL-1, as-synthesized and calcined, exhibits excellent stability.
Two Aluminophosphate Molecular Sieves Built from Pairs of Enantiomeric Structural Building Units
Angewandte Chemie International Edition, 2018
Herein we report the synthesis and structures of two new small-pore aluminophosphate molecular sieves PST-13 and PST-14 with mutually connected 8-ring channels. The structure of PST-13, synthesized using diethylamine as an organic structure-directing agent, contains penta-coordinated framework Al atoms bridged by hydroxy groups and thus edge-sharing 3-and 5-rings. Upon calcination, PST-13 undergoes a transformation to PST-14 with loss of bridging hydroxy groups and occluded organic species. The structures of both materials consist "nonjointly" of pairs of previously undiscovered 1,5-and 1,6-open double 4-rings (d4rs) which are mirror images of each other. We also present a series of novel chemically feasible hypothetical structures built from 1-open d4r (sti) or 1,3-open d4r (nsc) units, as well as from these two enantiomeric structural building units.
Synthesis and characterization of a novel crystalline AlPO4 molecular sieve, CFAP-7
Journal of Inclusion Phenomena, 1987
The novel crystalline aluminophosphate CFAP-7, having a characteristic X-ray powder diffraction pattern, has been synthesized hydrothermally in a system consisting of di-n-butylamine-(NH4)20-P205-A1203-H20 at 120 to 140~ the P205 and A1203 sources of which were provided by (NH4)3PO 4-3 H20 and A12(SO4) 3 in aqueous solution, respectively. Investigations by DTA, TG, DTG, XRD, and IR indicate transformation of the original product (form A) into more stable crystal forms B and C on heating at about 180~ and 240 ~ C, respectively, while liberating water and amine. Isotherms for the adsorption of water and methanol at 23 ~ C show that both form B and form C are molecular sieves with a window dimension of 4.3-4.9 A, and a methanol volume adsorbtion greater than that of water.
Inorganic Chemistry Communications, 2018
Highly crystalline aluminophosphate molecular sieve AlPO 4-11 was synthesized using both water and triethylene glycol (TEG) as solvent. The products were thoroughly characterized by powder X-ray diffraction analyses, thermogravimetric analyses (TGA), scanning electron microscope (SEM) analyses, and solid-state CP/ MAS NMR analyses. The results showed that both AlPO 4-11s had high degree of crystallinity and good thermal stability. The AlPO 4-11 synthesized with triethylene glycol had a different morphology from that synthesized with water. Thermogravimetric analysis (TGA) and 13 C CP/MAS NMR analyses showed that the bulky organic solvent molecules were encapsulated in the organic-amine-occupied channels of AlPO 4-11. This is the first observation that the bulky organic solvent molecules are included in the organic structure-directing agents occupied microporous aluminophosphate molecular sieves. The solvent molecules may act as a co-structure-directing agent in the formation of AlPO 4-11 under solvothermal conditions.
Journal of the American Chemical Society, 2004
Using a combination of computer modeling techniques, we have investigated the ability of benzylpyrrolidine and its fluorinated derivatives in ortho, meta, and para positions of the phenyl ring to direct the synthesis of the aluminophosphate AlPO-5. The oand p-fluoro derivatives are not good templates because of the poor packing of the template molecules inside the AlPO-5 pores, due to a repulsion provoked by the fluorine atoms. However, benzylpyrrolidine and the m-fluoro derivative do direct the synthesis of AlPO-5, the latter being a better template due to higher electrostatic interactions with the framework. We demonstrate that, at least when the synthesis is performed with an excess of template molecules, the ability of organic templating molecules to direct the synthesis of microporous materials depends not on the host-guest interaction energy per unit of template molecules, as usually calculated, but on the density of interaction energy, i.e., the energy per formula unit of the microporous network. The packing density of molecules inside the channel system must be taken properly into account. From the calculated location of the benzylpyrrolidine molecules and their m-fluoro derivative inside the inorganic network, we would expect the formation of stable dimers.
Catalysis Letters, 2000
The structure and morphology of both pure AlPO-5s and nickel containing AlPO-5s were affected by the preparation conditions such as pH value, nickel incorporated method (hydrothermal method or traditional incipient wetness impregnation). The dense tridymite phase of AlPO-5 can be formed by two controlling factors. One is controlling the pH at lower value to the AlO 4 and PO 4 moleculars to form AlPO 4 with dense phase, and the other is used the excess nickel adding to increase the crystallinity of AlPO-5 to form dense tridymite phase. The reactivity of PEG-400 amination was also affected preparation methods and conditions. At higher nickel loading, the nickel supported on AlPO-5 prepared by traditional incipient wetness impregnation forms the surface nickel species, and both the surface nickel species and nickel incorporated species form by the hydrothermal method. The amination catalysis indicates that the reactivity of PEG-400 prepared by incipient wetness impregnation method was higher than that prepared by hydrothermal method. The formation of the dense tridymite phase of AlPO-5 can be further determined by the X-ray powder diffraction (XRD). The nickel containing AlPO-5s prepared with lower pH value possesses only the tridymite phase and exhibit higher catalytic reactivity. It appears that the trydimite structure can improve the catalytic activity for PEG-400 amination due to the grain size of the formed crystal of NiAlPO-5 is smaller than the catalyst without the formation of the trydimite phase.
The hydrothermal synthesis of aluminophosphate molecular sieve type AlPO4-11 was processed from chemicals containing psueudobohemite, 85% phosphoric acid, water, and di-isopropylamine as templating agent. The crystallization of the samples was studied by taking samples in times from 2 to 74 hours. The obtained white powder products have been characterized by XRD patterns, FT-IR spectra, thermogravimetric data, scanning electron microscopy and pH measurement of the mother liquor. The pore volume, as determined from TG and DTG curves, was ca. 0.17 cm3g-1. The crystallization process of the aluminophosphate exhibited in its initial phase a behavior of first order reaction with a specific velocity constant of ca. 0.25 h-1, as determined from XRD and FT-IR data.
Chemistry of Materials, 2010
The novel aluminophosphate STA-15 (St Andrews microporous solid-15) is prepared by hydrothermal synthesis in the presence of tetrapropylammonium hydroxide (TPAOH), which acts as a structure directing agent. The crystallization is accelerated by the addition of low concentrations of tetraphenylphosphonium or other bulky organic cations, and the purity is improved by the addition of silica to the gel, but these additives are not included in the final crystalline product. The structure of STA-15 was solved by a combination of synchrotron X-ray powder diffraction and modeling. The asprepared form of STA-15 (Iba2, a = 14.7953(1) Å , b = 27.3634(3) Å , c = 8.34464(6) Å at 100 K) has unit cell composition Al 32 P 32 O 128 (OH) 1.8 TPA 1.8 3 3H 2 O. It has a system of one dimensional channels, limited by strongly elliptical 12-membered rings (12 tetrahedral cations and 12 oxygen atoms, 8.7 Â 5.7 Å) in which the TPA þ cations reside. The charge-balancing hydroxide ions are coordinated to framework Al, as shown by 27 Al and 31 P MAS NMR. STA-15 is stable to removal of the organic and hydroxyl species upon calcination in oxygen, leaving a microporous solid with a pore volume of 0.11 cm 3 g-1 and showing uptakes of n-hexane and toluene (at 297 K, p/p o = 0.10) of 0.48 and 0.69 mmol g-1 , respectively.
Synthesis and characterization of AIPO4-5RT molecular sieve at room temperature
Zenodo (CERN European Organization for Nuclear Research), 2006
Aluminophosphate molecular sie,•e AIPO~-SRT (AIP0~-5, prepared at room temperature) have been synthesized using hexamcthylem:imine template at room temperature for the first time. Gel composition AbOJ : P10s : 1.16HEM : 4SH10 aging for 12 h 111 room lempct•ature, and in 24 h, 473 K are the standard reaction conditions for synthesis of AIP04-S. Studies on above gel composition ut room temperature shows the Jlrcsence of AII'0~-5 crystals. Both the alumlnophosphates have been characterized by clemenl:tl mml)sis, XRD, SEM, FT-IR, TWI>TA, and 13 C, 17 AI und 31 p MASNMR techniques. XRD analysis of Ali'04-SRT shows llmt the pre~ence ol' low intensed pseudohoehmite sample. SEM shows the morphology nanosized crystals along with platelets. TGIDTA unuly~is reveals the presence of maximum live stages elimination of templates. Carbon and nitrogen analysis shows that the presence of l'our template molecules per unitcell. 13 C MASNMR analysis shows the interaction of template with structure of the framework. 17 AI MASNMR shows the presence of small amount of octahedral coordination besides the rest are in tetrahedral co-ot•dinalion. 31 P MASNMR shows the prcscn.cc of two environmentally different tetrahedrally coordinated phosphorous atoms.
Synthesis novel aluminophosphate molecular sieves at atmospheric pressure
Current World Environment, 2006
Novel small pore aluminophosphates molecular sieves AlPO 4-Atm1, AlPO 4-Atm2 and AlPO 4-Atm3 have been synthesized using hexamethyleneimine template at atmospheric pressure (373K) for the first time. Gel composition Al 2 O 3 : P 2 O 5 : 1.16HEM: 45H 2 O was taken as the standard one which gives AlPO 4-Atm12. Change in water molar ratio to 67.5 gives AlPO 4-Atm2. On changing the aluminium source from catapal B to aluminium isopropoxide in same molar gel composition gives AlPO 4-Atm3. All the materials were characterized by XRD, SEM, TG/DTA, C & N analysis, FT-IR and MASNMR analysis. Elemental analysis shows that Al and P are in equal molar composition. XRD analysis shows that the synthesized samples are highly crystalline and new. SEM shows the morphology change with structure. TG/DTA analysis reveals the presence of maximum four stage elimination of templates. Carbon and nitrogen analysis gives the amount of template present in the sample. 27 Al MASNMR shows the presence of single type tetrahedrally coordinated aluminium atoms in AlPO 4-Atm1. 31 P MASNMR of the same sample shows the presence of two type of tetrahedrally coordinated phosphorous atoms.