Characterization and Catalytic Properties of MAPO-36 and MAPO-5: Effect of Magnesium Content

Machado, Manuel; Pérez‐Pariente, Joaquín; Sastre, Enrique; Cardoso, Dilson; Giotto, Marcus; García-Fierro, José Luis; Fornés, Vicente

doi:10.1006/jcat.2001.3445

Cited by 28 publications

(22 citation statements)

References 21 publications

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“…Moreover, The MAPO mixtures present a drop in the BET surface area and micropore volume ( Table 2, MA1-MA3) compared to the AlPO 4 -n products, and the drop is more pronounced with the increase in the Mg content. In contrast, in the hydrothermal synthesis of MAPO molecular sieves, [20,21] the micropore volumes would not exhibit such a noticeable decrease. This is likely due to the poor solubility of Mg species in ionic liquid so that the excessive Mg materials would not dissolved in the ionic liquid but formed extra-framework species probably located at the outer surface or occluded in channels.…”

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confidence: 80%

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Ionothermal Synthesis of Magnesium‐Containing Aluminophosphate Molecular Sieves and their Catalytic Performance

Wang

et al. 2008

Chemistry A European J

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confidence: 80%

“…The first maximum around 220 8C was assigned to weakly bound ammonia and the second one at 330 8C should be attributed to the ammonia desorbed from the strong acid sites originating from the substitution of Mg 2 + for Al 3 + in the framework. [20] For the Table 1. Synthesis details and conditions for the preparation of MAPO structures.…”

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confidence: 99%

Ionothermal Synthesis of Magnesium‐Containing Aluminophosphate Molecular Sieves and their Catalytic Performance

Wang

et al. 2008

Chemistry A European J

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“…The X-ray photoelectron spectroscopy (XPS) core-level spectra were collected on the typical sample Mgb(50) plus the controls of b,M g (ex) -b,a nd Mg (im) -b.I nt he O1ss pectra, peaks appear at 532.85, 533.5, 534.5, and 536 eV,r espectively,f or Mgb(50), Mg (im) -b,M g (ex) -b,a nd b (Figure 2A). As ignificant shift to lower binding energies is observed for Mgb (50) in contrast to b,w hich is attributable to the incorporated Mg ions with weak electronegativity,w hich increases the electron density of Oa toms. [46] The Si 2p peak is centered at around 107.1 eV for b,w hich shifts to 105.5, 104.2, and 103.7 eV for Mg (ex) -b, Mg (im) -b,a nd Mgb,r espectively ( Figure 2B).…”

Section: Resultsmentioning

confidence: 99%

“…[47,48] Am ore significant shift of the O1sa nd Si 2p signals occurs for Mgb(50) than for Mg (im) -b and Mg (ex) -b,s uggesting that in situ incorporated Mg species favors more negative Os pecies, in accordance with our previous observations. [49,50] The basicity of zeolitesi sc losely related to the negativity of Os peciesa nd more negative Os pecies usuallym ean enhanced basicity. [45] In the CO 2 temperature-programmed desorption( TPD) curves, the Mgb(n)s amples demonstrate three CO 2 desorption peaks in the ranges of 110-130 8C, 270-300 8C, and 500-520 8C, respectively identifiedt ot he weak, medium, and strong basic sites (Figure2C).…”

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confidence: 99%

Construction of Acid–Base Synergetic Sites on Mg‐bearing BEA Zeolites Triggers the Unexpected Low‐Temperature Alkylation of Phenol

et al. 2017

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Novel Mg‐bearing BEA zeolites are synthesized to simultaneously endow significantly enhanced basicity without compromising acidity over the zeolite framework. Serving as efficient solid acid–base bifunctional catalysts, they achieve the liquid‐phase selective methylation of phenol with methanol to produce o‐ and p‐cresol (o/p=2) under mild conditions. The method is readily extendable to the alkylation of phenols with various alcohols. Stereo‐ and regioselectivity (>95 % for p‐product) was attained on the alkylation of phenol with bulky tert‐butyl alcohol, rendering the first acid–base cooperative shape‐selective catalysis relying on the basicity of zeolites. A preliminary mechanistic analysis reveals that the remarkable activity and shape‐selectivity come from the superior special acidic–basic synergetic catalytic sites on the uniform microporous channels of the BEA zeolite.

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“…The rst one around 220 C should be attributed to the weakly bounded ammonium, while the second one above 300 C, which is absent in the proles of AlPOs mixture, represents the strong acid site generating by the isomorphous substitution of magnesium into the framework. 11 The 27 Al MAS NMR spectra (Fig. 4) show an intense signal of tetrahedral coordinate aluminium in the framework at about d ¼ 38 ppm, 12,13 and the disappearance of the ve-coordinated aluminum peak indicates the absence of uorine in the structure.…”

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confidence: 97%

Isomorphous substitution induced ionothermal synthesis of magnesium aluminophosphate zeolites in fluoride-free media

2016

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Magnesium aluminophosphate zeolites (MgAPOs) with AEL, AFI and ATS structures were ionothermally synthesized in a fluoride-free system depending on the structure of the ionic liquids and the concentration of magnesium, where the incorporation of magnesium into the framework induced their crystallization, resembling that of fluoride ion in aluminophosphate analogues formation.Crystalline microporous aluminophosphates (AlPOs) based on strict alternation of AlO 4 and PO 4 tetrahedra are known as a prominent family of zeolitic materials. 1 Unlike aluminosilicate zeolite analogues, the framework of aluminophosphates is generally neutral, which limits their catalysis and ion-exchange functionality. Fortunately, the lattice Al and/or P can be isomorphously replaced by silicon and/or other metal atoms to form an anion zeolitic framework with Brønsted acid sites and/ or catalytically active metal centers, i.e. silicon-or metalsubstituted aluminophosphates, 2 which are of great signi-cance for their established and potential catalytic applications, for instance, paraffin isomerization and methanol to olen process. 3 In recent years, ionothermal synthesis, a method that uses ionic liquid as both solvent and template, has exhibited unique features and potential advantages over traditional hydrothermal and solvothermal synthesis in preparing aluminophosphate-based zeolites, as well as metal-organic frameworks and inorganic-organic hybrids. 4 For example, ionic liquid's negligible vapor pressure allows the synthesis in atmospheric vessels and the safer use of microwave heating; 5 ionic liquid's different chemistry and structural variety associated with the use of amines displays great potential to prepare zeolitic materials with novel structures and compositions. 6 Till now, several heteroatom-, including Co-, Mg-, Fe-, Mn-, Zn-, substituted aluninophosphate zeolites have been obtained by this method. 6b,7 Remarkably, a new cobalt-substituted aluminophosphate named SIZ-7 (SIV structure) with 3-dimensional 8-membered ring channels of zeolitic structure was ionothermally prepared by Morris et al.; 6b MgAPOs with AEL and AFI structures were successfully prepared by Wang et al. in uoride-containing ionothermal media, exhibiting excellent catalytic performance in the isomerisation of long-chain paraffin. 7a During the ionothermal synthesis of these materials, HF is always used and considered as one of the very important synthesis variables. In addition to the role of promoting the crystallization kinetics, uoride appears to be important in obtaining the full condensed structures of AlPOs without hanging P-O bonds, which is always stable for removal of the templates and thus to create the porosity. 4a Furthermore, Ma et al. proposed that during the synthesis of AlPOs, uoride could incorporated into the AFI structure and plays the role of structure-directing agent. 8 However, uoride in the synthesis media due to its toxicity and causticity is not desirable from an industrial viewpoint. Moreover, it was also reported that HF...

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Characterization and Catalytic Properties of MAPO-36 and MAPO-5: Effect of Magnesium Content

Cited by 28 publications

References 21 publications

Ionothermal Synthesis of Magnesium‐Containing Aluminophosphate Molecular Sieves and their Catalytic Performance

Ionothermal Synthesis of Magnesium‐Containing Aluminophosphate Molecular Sieves and their Catalytic Performance

Construction of Acid–Base Synergetic Sites on Mg‐bearing BEA Zeolites Triggers the Unexpected Low‐Temperature Alkylation of Phenol

Isomorphous substitution induced ionothermal synthesis of magnesium aluminophosphate zeolites in fluoride-free media

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