Aluminophosphate Molecular Sieves Research Articles

An Aluminophosphate Molecular Sieve with 36 Crystallographically Distinct Tetrahedral Sites

AbstractThe structure of the new medium‐pore aluminophosphate molecular sieve PST‐6 is determined by the combined use of rotation electron diffraction tomography, synchrotron X‐ray powder diffraction, and computer modeling. PST‐6 was prepared by calcination of another new aluminophosphate material with an unknown structure synthesized using diethylamine as a structure‐directing agent, which is thought to contain bridging hydroxy groups. PST‐6 has 36 crystallographically distinct tetrahedral sites in the asymmetric unit and is thus crystallographically the most complex zeolitic structure ever solved.

An Aluminophosphate Molecular Sieve with 36 Crystallographically Distinct Tetrahedral Sites

The structure of the new medium-pore aluminophosphate molecular sieve PST-6 is determined by the combined use of rotation electron diffraction tomography, synchrotron X-ray powder diffraction, and computer modeling. PST-6 was prepared by calcination of another new aluminophosphate material with an unknown structure synthesized using diethylamine as a structure-directing agent, which is thought to contain bridging hydroxy groups. PST-6 has 36 crystallographically distinct tetrahedral sites in the asymmetric unit and is thus crystallographically the most complex zeolitic structure ever solved.

Turning phosphatizing wastewater into zinc-incorporated aluminophosphate molecular sieve with an enhanced catalytic performance

Zinc-incorporated aluminophosphate molecular sieve (ZnAPO-34) has been successfully synthesized from Zn-contained phosphatizing wastewater. More than 90% of Zn and P were removed from wastewater after synthesis. The synthesized materials were characterized by X-ray diffraction, small angle X-ray diffraction and ammonia temperature programmed desorption. As a result, these samples were proven to be typical ZnAPO-34, which possessed mesoporous structure together with a great number of Bronsted and Lewis acid sites. Furthermore, the synthesized ZnAPO-34 showed 80% catalytic activity and 80% selectivity in cyclohexane oxidation to cyclohexanol. The higher activity and selectivity could be ascribed to the incorporation of Zn in the aluminophosphate molecular sieve.

Plasma-catalytic degradation of anthraquinonic acid green 25 in solution by gliding arc discharge plasma in the presence of tin containing aluminophosphate molecular sieves

In this paper, the plasmacatalytic removal of an anthraquinonic dye type acid green 25 (AG 25) in aqueous solutions has been investigated in the presence of microporous tin containing aluminophosphates as catalysts under a gliding arc discharge plasma.The catalysts have been synthesised in AEL and AFI structure types by static hydrothermal crystallisation. These materials were characterised by elemental analysis, X-ray diffraction, scanning electron microscopy, N2 adsorption measurements (BET) and Mössbauer spectroscopy. These analyses showed significant catalytic properties of these materials.The degradation process has been monitored during the experimental runs through UV/visible spectroscopy and chemical oxygen demand (COD). The results showed a good synergetic effect between the tin-containing aluminophosphate particles and the highly reactive plasma species. Moreover, it was found that these catalysts can be reused several times.Kinetics of the dye removal has also been investigated on the basis of the Langmuir–Hinshelwood (L–H) model.

Template removal from AFI aluminophosphate molecular sieve by Pd/SiO2 catalytic hydrocracking at mild temperature

Pd/SiO2 catalytic hydro-cracking is applied to remove triethylamine template in an AFI type MnMgAlPO-5 molecular sieve. The triethylamine template reacts with spillover hydrogen inletting from the Pd/SiO2 catalyst, and is hydro-cracked to small molecules at a mild temperature (613K). This behavior is distinguish to the conventional template removal method of calcination above 823K, and consistently proved by H2-TPR/MS, TG/MS, and N2-isotherms results. The catalytic hydro-cracking method does not damage the crystal structure of MnMgAlPO-5, indicated by XRD characterization. Its novelty is suggested as reserving the local symmetric structure of MnMgAlPO-5 (i.e., keeping framework Mn and Mg), consistently verified by EPR, UV–vis, and Raman spectra. This provides an alternative option for the template removal from molecular sieves.

ChemInform Abstract: Luminescent Carbon Dots in a New Magnesium Aluminophosphate Zeolite.

AbstractThe structure of the new magnesium aluminophosphate molecular sieve materials (III) (obtained with 86 wt.% yield; monoclinic, space group P21/c, Z = 4) and (IV) (monoclinic, P21/n, Z = 4) are determined by single crystal XRD.

A simple method for the synthesis of thermally stable large pore mesoporous aluminophosphate molecular sieves

Mesoporous aluminophosphate AlPO4 with high thermal stability has been simply synthesized from lauric and myristic triglycerides, as a novel templating agent. The ordered sample showed large pore size (153Å) and pore volume (0.37cm³/g), and also presenting a broad pore size distribution. The crystalline nature of the material was detail characterized by the powder X-ray diffraction method and supported by the observation using scanning electron microscope. The material has high thermal stability towards thermal treatment up to 1200°C. The catalyst shows very high activity for the esterification of n-butanol and acetic acid and also acts as a good adsorbent for the removal of organic dyes from aqueous solution.

Removal of anionic dye from aqueous solution by using nanoporous aluminophosphate molecular sieves

Removal of anionic dye from aqueous solution by using nanoporous aluminophosphate molecular sieves

Evaluation of Iron-Containing Aluminophosphate Molecular Sieve Catalysts Prepared by Different Methods for Phenol Hydroxylation

Three iron-containing AlPO4-5 molecular sieve catalysts (i.e. FeAlPO-5-Iono, FeAlPO-5-Hydro and FeAlPO-5-Imp) were prepared by ionothermal synthesis, direct hydrothermal synthesis and impregnation method, and characterized by various techniques. N2 adsorption/desorption measurements, together with the results of SEM and TEM, showed that FeAlPO-5-Iono was a new type of aluminophosphate molecular sieve with hierarchical micro- and meso-porous structure, whereas both FeAlPO-5-Hydro and FeAlPO-5-Imp were typical microporous materials. DR UV–Vis analysis suggested that the order of the amounts of isolated Fe3+ species in these three samples was as follows: FeAlPO-5-Hydro > FeAlPO-5-Iono > FeAlPO-5-Imp. However, the order of their catalytic performances towards phenol hydroxylation was in opposition to that of the amounts of isolated Fe3+ species. Detailed analysis revealed that it was textural properties of these catalysts that determined phenol conversion and dihydroxylbenzene selectivity. The catalyst-recycling tests suggested that extra-framework iron clusters were readily leached into the reaction system and had great influence on the hydroxylation of phenol. Due to the sole presence of isolated Fe3+ species and enhanced mass transport of reactants and products to/from these active sites, FeAlPO-5-Hydro was found to have the best reusability among these catalysts. .

Kinetic and Isotherm Studies of Removal of Metanil Yellow Dye on Mesoporous Aluminophosphate Molecular Sieves

The removal of metanil yellow dye was studied through adsorption on meosporous aluminophosphate molecular sieves at different experimental conditions like contact time, pH, dye concentration and adsorbent dosage. The experimental values were adopted to adsorption kinetic and adsorption isotherm equations for understanding the rate and mechanism of adsorption process. The adsorption process was well fitted with pseudo first second kinetics and Langmuir adsorption isotherm. The maximum adsorption capacity of metanil yellow on adsorbent was 75 mg/g. This study concludes that the mesoporous aluminophosphate material is a good material for removal of metanil yellow dye.

Cr-Substituted Mesoporous Aluminophosphate Molecular Sieve: Synthesis, Characterization, Crystallization Kinetics and Catalytic Activity

Cr-substituted mesoporous aluminophosphate molecular sieve (Cr-MAP) was synthesized and characterized. Crystallization kinetics curves measured as an index to the relative degree of crystallinity, according to the Arrhenius equation to calculate the apparent nucleation activation energy and crystal growth activation energy of Cr-MAP, which was 63.7 and 14.7 kJ• mol-1, respectively. Cr-MAP had highly catalytic activity for fabricating acetophenone by selectively oxizing ethylbenzene. Using tert-butylhydroperoxide as oxidant and chlorobenzene as solvent at 100 °C for 8 h, acetophenone selectivity, acetophenone yield and ethylbenzene conversion reaches 85.4, 62.2 and 72.8 %, respectively.

Multinuclear Solid-State NMR Studies on the Formation Mechanism of Aluminophosphate Molecular Sieves in Ionic Liquids

In the present work, multinuclear solid-state NMR techniques together with power X-ray diffraction (XRD) and scanning electron microscopy (SEM) were employed to monitor the crystallization process of aluminophosphate AlPO4-11 molecular sieves in 1-ethyl-3-methylimidazolium bromide ([emim]Br) ionic liquids (ILs). The local environments of the selected solid samples were probed by one-dimensional 27Al, 31P, and 19F MAS NMR experiments, and more information was obtained from two-dimensional 27Al→31P heteronuclear correlation (HETCOR) and 27Al triple-quantum MAS (3Q MAS) experiments. It is found that a large amount of amorphous aluminophosphates was formed with the F–Aloct–O–Ppar and Altet–O–Ppar structures in the initial stage of aging. With increasing crystallization time, the partially condensed framework phosphorus species disappeared gradually and became fully condensed. Meanwhile, the octahedral Al was transformed into the pentahedral and tetrahedral Al species with the structures of F–Alpenta–O–Pful and Altet–O–Pful in the AlPO4-11 frameworks. During the crystallization process, [emim] cations acting as the structure-directing agents were occluded into the channels, and F– anions were connected with pentahedral Al in the final AlPO4–11 phase. All of these findings can allow proposing a possible formation mechanism for the synthesis of AlPO4-11 in ionic liquids.

Syntheses and characterizations of aluminophosphate molecular sieves AFI guided by missing value estimation on database of aluminophosphate syntheses

Several experiments have been performed based on the results of four missing value estimation methods on the database of AlPO syntheses. The target products, aluminophosphate molecular sieves with AFI topology, have been prepared by using triethylamine (TEA), N,N-dimethylbenzylamine (BDMA) and N-(2-aminoethyl)-piperazine (AEP) as the structure-directing agents, and their structures have been characterized by PXRD, SEM, TG, CHN, ICP and NMR. The experimental results show that BP impute method is the most effective approach for estimation of missing data of microporous aluminophosphates. This work further indicates that data mining provides a useful guidance for the rational synthesis of inorganic microporous materials.

Relationship Between Framework Distortion and Heteroatom-substitution in Aluminophosphate Molecular Sieves

Aluminophosphate molecular sieve frameworks AFI,AEL,ATO,SBS,SBE,SBT,JRY and MAPO-CJ69 were optimized by means of computer simulation methods.The standard deviations of Al—O,O—O,Al—P,and P—P distances in AlO4 and AlP4 tetrahedra,as well as their continuous shape measure(CShM) values were calculated.Calculation results show that the introduction of heteroatoms is necessary for the formation of molecular sieve frameworks with high distortions.In addition,Heteroatoms occupy the most distorted tetrahedra sites.On the contrary,zeolite frameworks with low distortions can be synthesized without the addition of heteroatoms.These results agreed well with the experimental results.

Adsorption and diffusion of nitrogen, methane and carbon dioxide in aluminophosphate molecular sieve AlPO4-11

The knowledge about the adsorption and diffusion properties (specially about diffusion) of aluminophosphate molecular sieves is very scarce in the literature. These materials offer interesting properties as adsorbents as they have a polar framework and do not contain charge-balancing cations. In this work, the adsorption isotherms of nitrogen, methane and carbon dioxide over an AlPO4-11 sample synthesized in our laboratories have been measured with a volumetric method at 25, 35, 50 and 65 °C over a pressure range up to 110 kPa. The adsorption capacities of each gas are determined by the strength of interaction with the pore surface (carbon dioxide > methane > nitrogen). The equilibrium selectivity to carbon dioxide is quite high with respect to other adsorbents without cations due to the polarity of the aluminophosphate framework. The adsorption Henry’s law constants and diffusion time constants of nitrogen, methane and carbon dioxide in the synthesized AlPO4-11 material have been measured from pulse experiments. A pressure swing adsorption (PSA) process for recovering methane from a carbon dioxide/methane mixture (resembling biogas) has been designed using a dynamic model where the measured adsorption equilibrium and kinetic information has been incorporated. The simulation results show that the proposed process could be simpler than other PSA processes for biogas upgrading based on cation-containing molecular sieves such as 13X zeolite, as it can treat the biogas at atmospheric pressure, and it requires a lower pressure ratio, to produce high purity methane with high recovery.

Ionothermal Synthesis of AEL-Type Aluminophosphate Molecular Sieve Membrane and Its Formation Mechanism

Ionothermal Synthesis of AEL-Type Aluminophosphate Molecular Sieve Membrane and Its Formation Mechanism

Investigation on NOx adsorption in [M′]-MAPO-5 (M = Si, Ti; M′ = Ag, Cu) by density functional theory calculation

NO, N2O and NO2 adsorption in [M′]-MAPO-5 (M=Si, Ti; M′=Ag, Cu) models of the modified aluminophosphate molecular sieves was investigated by density functional theory (DFT) method. The equilibrium structural parameters and adsorption energies were obtained and compared. The structural parameters of NO and NO2 in the adsorbed state had a distinct change than that of N2O compared to their free gas state. [M′]-MAPO-5 was more effective for the activation of NOx molecule compared to [M′]-AlMOR (M′=Ag, Cu) models of the modified mordenite in our previous studies. The adsorption energies data indicated that adsorption strength of NOx followed the decreasing order of NO2>NO>N2O. And adsorption complexes in η1-N mode were much stabler than that in η1-O mode, which was similar to that in [M′]-AlMOR. [Cu]-MAPO-5 had a much stronger adsorption for NOx than [Ag]-MAPO-5. And [M′]-SiMOR had a little stronger adsorption for NOx than [M′]-TiMOR. Furthermore, the resistance capabilities of [M′]-MAPO-5 to SO2, H2O and O2 were studied and analyzed. The interaction mechanism of NOx adsorption in [M′]-MAPO-5 was also discussed by natural bond orbital (NBO) analysis, which was in reasonable agreement with the adsorption interaction strengths.

Hazardous dyes removal from aqueous solution over mesoporous aluminophosphate with textural porosity by adsorption

Dye pollution in aquatic nature produce serious environmental effects. In this investigation, mesoporous aluminophosphate molecular sieve synthesized and applied for the removal of hazardous dyes Malachite green (MG) and Methylene blue (MB). In the synthesis of mesoporous aluminophosphate (AlPO4) molecular sieve, the structure-directing agent, long-chain alkylbenzene has been used as a template. The template used for the synthesis of mesoporous material is environmentally biodegradable. The mesoporous AlPO4 was synthesized by the absence of an organic base, tetramethyl ammonium hydroxide (TMAOH) which is necessary to maintain the pH for the conventional AlPO4 synthesis methods. The synthesized mesoporous AlPO4 has high thermal stability up to 1173K and large porosity nature (40nm). It was confirmed by the characterization techniques such as low-angle XRD, FT-IR, TGA and BET surface area analysis. The morphology of the material was explained by using SEM and TEM. The hazardous dyes MG and MB removal studied under the various conditions like contact time, dye concentration, temperature, pH and adsorbent dosage to examine the adsorption characteristics of the newly synthesized mesoporous AlPO4 molecular sieves.

ChemInform Abstract: Progress in Heteroatom‐Containing Aluminophosphate Molecular Sieves

AbstractReview: 35 refs.

Synthesis, characterization and template removal of an iron-containing aluminophosphate molecular sieve with LAU topology

Iron(II)-substituted LAU-zeotype aluminophosphate molecular sieve (denoted as FeAPO-LAU) was synthesized successfully by using imidazole as template in the solvothermal system. The detemplation process was studied to elucidate the stability and microporous characteristics of FeAPO-LAU. In situ temperature-dependent X-ray diffraction analyses indicated that the framework of FeAPO-LAU possessed higher thermal stability and maintained the framework integrity until 923K. The organic templates could be removed by stage-temperature-programmed calcination using lower heating rate in O2 atmosphere, which gave rise to the sample with surface areas of ca. 105m2/g. NH3-temperature programmed desorption (NH3-TPD) analysis showed that detemplated FeAPO-LAU had a weak acidity. Magnetic measurement revealed that both as-synthesized and detemplated FeAPO-LAU showed antiferromagnetic behaviour.