Synthesis Of Aluminophosphate Research Articles

Ultrafast and continuous synthesis of an aluminophosphate type zeolite in microchannel and the hydrogenation of α-pinene

A highly efficient method was proposed for fast and continuous synthesis of LTA-type aluminophosphate (AlPO4-LTA) molecular sieves. The precursor was first synthesized in batch methods, then the precursor and tetramethyllamine hydroxide were coordinated to direct the synthesis of molecular sieves in a reaction system containing a poly (tetrafluoroethylene) (PTFE) microchannel reactor, which reduced the energy costs associated with mixing and cooling of reactant solutions. The reaction conditions, including molar ratio of reagents, temperature and flow rate, have also been rapidly optimized. The AlPO4-LTA have high crystallinity, high thermal stability, granule size (ca. 150 nm) and large surface area (679 m2/g). In addition, the hydrogenation of α-pinene catalyzed by Ni/AlPO4 nanocomposites was achieved with α-pinene conversion rate of 95.1% and cis-pinane selectivity of 95.9%, the catalyst had high activity during five cycles.

Solid-State Synthesis of Aluminophosphate Zeotypes by Calcination of Amorphous Precursors

Because of the growing interest in the applications of zeolitic materials and the various challenges associated with traditional synthesis methods, the development of novel synthesis approaches remains of fundamental importance. Herein, we report a general route for the synthesis of aluminophosphate (AlPO) zeotypes by simple calcination of amorphous precursors at moderate temperatures (250-450 °C) for short reaction times (3-60 min). Accordingly, highly crystalline AlPO zeotypes with various topologies of AST, SOD, LTA, AEL, AFI, and -CLO, ranging from ultra-small to extra-large pores, have been successfully synthesized. Multinuclear multidimensional solid-state NMR techniques combined with complementary operando mass spectrometry (MS), powder X-ray diffraction, high-resolution transmission electron microscopy, and Raman characterizations reveal that covalently bonded fluoride in the intermediates catalyze the bond breaking and remaking processes. The confined organic structure-directing agents with high thermal stability direct the ordered rearrangement. This novel synthesis strategy not only shows excellent synthesis efficiency in terms of a simple synthesis procedure, a fast crystallization rate, and a high product yield, but also sheds new light on the crystallization mechanism of zeolitic materials.

Tailoring Water Adsorption Capacity of APO-Tric

Microporous triclinic AlPO4-34, known as APO-Tric, serves as an excellent water adsorbent in thermal energy storage, especially for low temperature thermochemical energy storage. Increased water adsorption capacity of thermochemical material usually leads to higher thermal energy storage capacity, thus offering improved performance of the adsorbent. The main disadvantage of aluminophosphate-based TCM materials is their high cost due to the use of expensive organic templates acting as structure directing agents. Using ionic liquids as low cost solvents with associated structure directing role can increase the availability of these water adsorbents for TES applications. Here, a green synthesis of APO-Tric crystals at elevated and ambient pressure by using 1-ethyl-3-methyl imidazolium bromide ionic liquid is presented. Large 200 µm romboid shaped monocrystals were obtained at 200 °C after 6 days. The structure of APO-Tric and the presence of 1,3-dimetylimidazolium cation in the micropores were determined by single crystal XRD at room temperature and 150 K. Water sorption capacity of APO-Tric prepared by ionothermal synthesis at elevated pressure increased in comparison to the material obtained at hydrothermal synthesis most probably due to additional structural defects obtained after calcination. The reuse of exhausted ionic liquid was also confirmed, which adds to the reduction of toxicity and cost production of the aluminophosphate synthesis.

An efficient method for the ionothermal synthesis of aluminophospahte with the LTA framework type

Abstract The synthesis of aluminophosphate (AlPO) with the LTA framework type was performed for the first time in 1-butylpyridinium chloride ([C4Py]Cl) which functions as solvent as well as structure-directing agent (SDA). The AlPO-LTA was synthesised only after 2 h of crystallisation time at 160 °C without the addition of a co-SDA. [C4Py]Cl remains intact after synthesis, easily recovered and reused. Thus, an efficient and facile synthesis method for the AlPO-LTA is presented.

Use of pinene as a solvent for the synthesis of aluminophosphate and its application in the hydrogenation of pinene

Abstract In a novel application, pinene was employed as a solvent to prepare aluminophosphate. The product (known as APO-PT) possessed a well-crystallized AFI topology with prismatic morphology and possessed a higher BET specific surface area (297.70 m2 g−1) and larger pore volume (29.65 × 10−2 cm3 g−1). APO-PT showed a mesoporous structure due to the influence of solvent during the crystallization process. During the detemplation process, the sample could maintain its framework at 800 °C, which indicated good thermal stability. The kinetics of the crystallization process was investigated using a new and more appropriate method, and the results showed that the apparent nucleation-activation energy and apparent growth-activation energy of the APO-PT with an AFI phase were 65.45 and 92.94 kJ mol−1, respectively. Aluminophosphate was used as a support in the preparation of a Ni/APO-PT catalyst and was applied for the hydrogenation of pinene and exhibited excellent performance. The selectivity of cis-pinane was 96.2% under 98.7% of the conversion of pinene over the Ni/APO-PT catalyst, which was considerably higher than that observed over the traditional catalyst due to its special pore structure.

Performance of three different cations based on imidazolium ring as structure directing agents in the synthesis of aluminophosphates and silicoaluminophosphates microporous materials

Abstract In this work three different cations based on imidazolium rings, 2-ethyl-1,3,4-trimethylimidazolium (2E134TMI), 1,2,3-triethyl-4-methylimidazolium (123TE4MI) and 1,2,3-triethylimidazolium (123TEI), were employed as structure directing agents (SDA) for the synthesis of aluminophosphate and silicoaluminophosphate microporous materials. The cations allowed the crystallization of three different structures (AFI, CHA and AEI). Nevertheless, even though these SDAs are similar as in size, shape and flexibility conformational, they presented different specificity for these phases. While CHA structure was synthesized with 2E134TMI and 123 TMI4MI cations, the AEI phase was obtained only with 123TEI. The resulting materials were characterized by different chemical and physical-chemical techniques. A complementary computational study shows that the ability of 123TE4MI cation to crystallize CHA framework does not only depend on a good fitting of the cation itself within this framework cavity, but also on an adequate packing between cations within adjacent cavities. On the other hand, the best host-guest chemistry for 123TEI SDA occurs when occluded within the AEI framework cavities, explaining the experimental observations.

Sulfonium-based organic structure-directing agents for microporous aluminophosphate synthesis

Sulfur-centered phenyl, n-butyl, p-tolyl, and benzyl sulfoniums and sulfides were tested as organic structure-directing agents (SDAs) for the synthesis of crystalline microporous aluminophosphates (AlPOs) over various ranges of gel compositions, hydrothermal treatment temperatures, and crystallization times. Among the investigated compounds, triphenylsulfonium gave single-phase products of ATS-type AlPO and silicoaluminophosphate. Other sulfoniums yielded only non-porous, dense crystalline AlPOs. On the other hand, diaryl sulfides gave a tiny amount of AFI-type AlPO amid tridymite and amorphous phases. Based on the results, it was found to be reasonable that weakly basic sulfide could hardly act as a zeotype SDA due to the low protonation to sulfonium at the present synthesis pH.

Ionothermal synthesis of crystalline microporous aluminophosphates: Systematic study on the conditions affecting the framework type

In a systematic study on the synthesis of aluminophosphates (AlPOs) under ionothermal conditions, initially using 1-butyl-3-methylimidazolium bromide ([C4mim]Br) as ionic liquid solvent and structure-directing agent, the effect of the reaction conditions (i.e. molar P/Al, F/Al and ionic liquid/Al ratios, alternative fluoride sources, influence of the ionic liquid's cation or anion, temperature, reaction time) on the framework type was studied in detail. In [C4mim]Br, the formation of the more thermodynamically stable AEL framework type proceeds via AFI. The framework type can be changed by choosing another anion or cation of the ionic liquid. Hence, the successful ionothermal synthesis of the AFI framework AlPO is reported by using either N-ethylpyridinium bromide ([C2py]Br) or 1-butyl-3-methylimidazolium chloride ([C4mim]Cl). The mineraliser [Me4N]F, rather than HF, has been used for the first time as an alternative fluoride source in ionothermal synthesis, which can also affect the framework type. Hence, a very efficient synthesis of the LTA framework type is reported in [C4mim]Br using [Me4N]F. Ab initio molecular dynamics (AIMD) studies showed that the anion bridges between the aluminium atoms of the framework and the cation. The interaction is more favoured in the presence of the bromide than the chloride, which may be a clue to the question why the AEL framework is not formed in the chloride-based ionic liquid. This study opens several routes to pursue in the future as numerous ionic liquids are available which can be used in ionothermal synthesis.

Synthesis and Structural Characterization of a CHA-type AlPO4 Molecular Sieve with Penta-Coordinated Framework Aluminum Atoms.

The structure-directing effects of a series of polymethylimidazolium cations with different numbers of methyl groups as organic structure-directing agents (OSDAs) in the synthesis of aluminophosphate (AlPO4)-based molecular sieves in both fluoride and hydroxide media are investigated. On the one hand, among the OSDAs studied here, the smallest 1,3-dimethylimidazolium and the largest 1,2,3,4,5-pentamethylimidazolium cations were found to direct the synthesis of a new variant of the triclinic chabazite (CHA)-type AlPO4 material, designated AlPO4-34(t)V, and the one-dimensional small-pore silicoaluminophosphate (SAPO) molecular sieve STA-6 in hydroxide media, respectively. On the other hand, the intermediate-sized 1,2,3,4-tetramethylimidazolium cation gave SSZ-51, a two-dimensional large-pore SAPO material, in fluoride media. Synchrotron powder X-ray diffraction and Rietveld analyses reveal that as-made AlPO4-34(t)V contains penta-coordinated framework Al species connected by hydroxyl groups, as well as tetrahedral framework Al, which contrasts with the distortions arising from the two F- or OH- bridges between octahedral Al atoms in all already known AlPO4-34 materials. The presence of Al-OH-Al linkages in this triclinic AlPO4-34 molecular sieve has been further corroborated by thermal analysis, variable-temperature IR,27Al magic-angle spinning NMR, and dispersion-corrected density functional theory calculations.

Co‐templating Ionothermal Synthesis and Crystal Structure of a New Layered Aluminophosphate from a Protic Deep Eutectic Solvent

AbstractProtic deep eutectic mixtures are usually composed of organic amine hydrochloride salts and hydrogen bond donors in a specific molar ratio. Ionothermal synthesis of aluminophosphate as an example, herein, was reported for the first time from an urea‐based protic eutectic mixture, consisting of diethylammonium chloride (DEACl) and 1,3‐dimethyl urea (DMU). As a result, a new two dimensional aluminophosphate with 4.8‐network, [CH3NH3]2[(C2H5)2NH2]Al3(PO4)4, has been successfully synthesized by co‐templating the DEA and methylamine in situ generated from the decomposition of DMU in the absence of HF. Compared to alkyl quaternary ammonium salts with more alkyl‐group connected with N atom, this kind of organic amine salts are more likely as the structure‐directing agents to synthesize aluminophosphates in urea‐based deep eutectic mixtures. It was also found that HF is crucial to the phase selectivity, a known compound with chain‐like structure was obtained with the single methylamine as a structure‐directing agent in the presence of HF. These materials were characterized by powder XRD, SEM, TG‐DSC, 13C CP‐MAS NMR and CHN analyses.

Triptycene structure-directing agents in aluminophosphate synthesis

The synthesis of aluminophosphates is investigated using a number of triptycene-based organic structure-directing agents (OSDA). These OSDAs are designed to synthesize extra-large pore and/or large cavity-containing molecular sieves. Starting from the hydrophobic triptycene molecule, OSDAs are prepared by introducing three amine-based centers that can be charged either by protonation in the acidic aluminophosphate reaction media or through quaternization. VPI-5 is synthesized using these tripytycene OSDAs, and the OSDAs are occluded inside the pores. This synthesis marks the first time VPI-5 has been made as a single phase with an OSDA occluded inside the framework of the as-made material that is not removed by simple washing with water or other solvents. Additionally, several other aluminophosphates with unknown structures are synthesized using these new OSDAs.

The synthesis of aluminophosphate and germanosilicate LTA using a triquaternary structure directing agent

The use of triquaternary organic structure directing agents (OSDAs) for the synthesis of microporous materials is relatively unexplored. Here a triquaternary OSDA prepared by reacting 1,2-dimethylimidazole with 1,3,5-tris(bromomethyl)benzene promotes the formation of LTA in the aluminophosphate or germanosilicate reaction chemistries.

Prediction of the formation of microporous aluminophosphates containing (6, 8)-rings using support vector machines

A support vector machine (SVM) method has been used on the database of aluminophosphate (AlPO) synthesis with ca. 1700 reaction data to predict the formation of AlPOs with (6, 8)-rings based on 20 synthetic parameters associated with the gel composition, solvent and templates. Furthermore, four zeotype structures with different channel systems, such as AEN, AWO, ERI and CHA have been computational classified in the family of (6, 8)-ring-containing AlPOs. Analysis results reveal that several synthetic parameters, particular the molar ratio of solvent/Al2O3 (F3), and the Van der Waals (VDW) volume (F14), the greatest length (F11), and the number of free rotated single bond (F20) of templates have significant effects in directing the formation of target structure. Using single or combinations of several parameters, a better classifier can be trained to distinguish the (6, 8)-ring-containing AlPOs with desired zeotype structure or not, and the classification accuracy is about 85%. This work demonstrates that the computational method together with database of AlPO synthesis provides a possibility to establish the relationship between the synthetic factors and the resulting structures, which is important in guiding the rational synthesis of microporous aluminophosphate materials.

Benzoylation for the recovery of structure directing agent (di-n-propylamine) from the process effluent of aluminophosphate synthesis

Di-n-propylamine (DPA), a structure directing agent for (silico)aluminophosphate (AlPO4) synthesis, is lost into the mother liquor (ML, 5–6 wt%) from the filtration step. A simple benzoylation reaction could recover DPA as N,N,-dipropylbenzamide (DPBA). The reaction also leads to the recovery of more AlPO4 and a decrease in the pollution caused by the ML.

Synthesis of aluminophosphate by the ionothermal method using factorial design

This work addresses the ionothermal synthesis of aluminophosphates with magnesium incorporation in order to generate ion exchange sites. The deep eutectic mixture of urea and choline chloride acts as the solvent and template. A central composite design was used to systematically study the effects of some synthesis parameters on types of aluminophosphates and their ion exchange capacity. XRD analysis revealed that condensed AlPO-CJ2, AEL, AEN, and GIS topologies were formed. Mg incorporation was confirmed by thermogravimetric analysis and ion exchange experiments. The statistical analysis showed that the percentage of eutectic mixture in the gel was the main variable affecting the ion exchange capacity, followed by the crystallization time and the percentage of Mg in the gel. The percentage of choline chloride in the eutectic mixture did not have an influence on the ion exchange properties.

Ionothermal synthesis of aluminophosphates used for ion exchange: Influence of choline chloride/urea ratio

A wide variety of industrial processes produce aqueous effluents that contain heavy metals. Considering the toxicity of metal polluted wastewaters, ion exchange appears as an easy and inexpensive option to remove metal ions from these effluents. There is currently much investigation on synthetic and natural materials to be used as cation exchangers. Among these materials, using microporous molecular sieves have been proposed due to their high surface area, porous diameter and ion exchange capacity. In this work, aluminophosphates (AlPOs) were prepared by the ionothermal method using the eutectic mixture urea/choline chloride (CCh) as solvent and template. Different CCh ratios in the eutectic mixture used in gel synthesis resulted in different structures with very distinguished ion exchange capacities. The main structures obtained were SIZ-2 and AlPO-CJ2. Varying the percentage of CCh in the gel synthesis mixture, it was observed that the AlPO-CJ2 structure is obtained using CCh percentages greater than 50%, while SIZ-2 is obtained using 25% and 33.3% CCh. The structure-directing the interrupted structure are the ammonium cations coming from the partial decomposition of urea. The SIZ-2 prepared using 25% CCh has a somewhat higher ion exchange capacity than that observed using 33.3% CCh. This result is very interesting since CCh is the most expensive component in the eutectic mixture.

Synthesis and characterization of a novel titanium aluminophosphate hollow nanosphere

A novel titanium aluminophosphate hollow nanosphere is synthesized and characterized for the first time. Characterization by various physicochemical techniques shows that the hollow nanosphere is a potential catalyst and applicable to various Industrial reactions. The X-ray diffraction analysis shows that the Initial peaks are in microporous materials region. The hollow size is 20 nm with 10 nm thickness shell. Use of titanium butoxide in aluminophosphate synthesis plays a crucial role on hollow sphere formation.

Cooperative Effect of Hydroxide and Fluorinated Organic Ions as Structure Directing Agent in the Synthesis of Crystalline Microporous Aluminophosphates

A combination of computational methods based on molecular mechanics, fluorescence, FTIR and magic-angle spinning NMR spectroscopies, and thermogravimetric analysis coupled with mass spectrometry have been employed to explain the structure directing effect of dibenzyldimethylammonium (dbdm) and its bis(ortho- and meta-fluorobenzyl) derivatives in the synthesis of aluminophosphates with AFI-type structure. We identify a supramolecular assembly of dbdm cations with hydroxide anions which compensate for their positive charge. These hydroxide anions appear to be also coordinated to framework aluminum atoms, bridging the organic SDAs and the framework walls. Such assembly is most promoted when the fluorine atom is located in the ortho position of the aromatic ring, which considerably enhances the electrostatic interaction with the inorganic network. The presence of the OH− counterion provides charge balance for the ortho-fluorinated SDA and leads to fewer framework defects. In the other cases, most of the posit...

Synthesis and physical properties of single crystals of zeolite-like aluminophosphates of the AFI type

The improvement of the procedure employed for hydrothermal synthesis of aluminophosphates of the AFI type (AlPO4) with the use of triethanolamine as a structure-forming template made it possible to grow large-sized AFI single crystals of high optical quality in the form of hexagonal prisms with a size of up to 2–3 mm along the c axis. The dc electrical conductivity and infrared spectra of the AFI crystals thus obtained were measured.

1-Alkyl-3-methyl Imidazolium Bromide Ionic Liquids in the Ionothermal Synthesis of Aluminium Phosphate Molecular Sieves

The systematic increase in alkyl chain length from 2 to 5 carbons in 1-alkyl-3-methyl imidazolium bromide ionic liquids is investigated in the ionothermal synthesis of aluminophosphate (AlPO) zeolite materials in sealed autoclaves. The effect of alkyl chain branching and the use of an imidazolium dication ionic liquid are also investigated. On addition of HF to the reaction mixture, a small amount of 1,3-dimethylimidazolium cation is formed in all cases (except when the alkyl chain length is 2), which acts as the structure directing agent (SDA) in the formation of AlPO molecular sieves with the CHA framework (SIZ-10). For 1-ethyl-3-methyl imidazolium bromide ionic liquids, the cation is incorporated intact into the SIZ-4 structure. The resulting materials are characterized by single-crystal X-ray diffraction and 13C MAS NMR.