Synthesis of mesoporous aluminophosphates-based materials using various copolymers as templates

O’Malley, Kathleen; Gil, A.; Curtin, Teresa

doi:10.1016/j.micromeso.2014.02.038

Cited by 3 publications

(4 citation statements)

References 22 publications

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“…Aluminium loading into MSN in order to produce active sites results in a decrease of the pore structure as compared with the pure MSN 4 . Protonation of mesoporous materials changes the pore structure as well as undesirable loss of 4-coordinated aluminium structure and appearance of 6-coordinated aluminium structure 5 . Introduction of platinum to the mesoporous silica materials usually combined with metal oxides such as Zr, Ir, Al and Mo oxides [6][7][8] which increased the catalytic activity.…”

Section: Introductionmentioning

confidence: 99%

“…4 Protonation of mesoporous materials changes the pore structure as well as causes an undesirable loss of the 4-coordinated aluminium structure and appearance of the 6-coordinated aluminium structure. 5 Introduction of platinum into mesoporous silica materials usually combined with metal oxides such as Zr, Ir, Al and Mo oxides [6][7][8] was found to increase the catalytic activity. The protonation process can be applied to increase the amount and strength of acidic sites through the generation of Brønsted acid sites.…”

Section: Introductionmentioning

confidence: 99%

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High activity of aluminated bifunctional mesoporous silica nanoparticles for cumene hydrocracking and measurement of molar absorption coefficient

et al. 2015

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Bifunctional mesoporous silica nanomaterials (MSN) with various Si/Al molar ratios of 7, 10, 20 and 50 in platinum supported (Pt/HAlMSN) were synthesized using sol-gel followed by post-synthesis methods. XRD and nitrogen sorption results confirmed the mesoporous structure with the surface areas of 537-775 m 2 g -1 . 27 Al NMR spectroscopy confirmed aluminium loading with tetrahedral, pentahedral and octahedral structures. Pyridine adsorbed IR results indicated that the aluminium incorporating led to generate strong Brønsted and Lewis acidic sites. Catalytic activity was investigated for cumene hydrocracking in a pulse microcatalytic reactor at the temperature range of 323-573 K which revealed that this activity depends on the number of Lewis and Brønsted sites. High yield of cumene conversion increased from Si/Al of 50 to 10 and decreased in Si/Al of 7 due to the presence of pentahedral Al and/or inactive tetrahedral Al atoms in Pt/HAlMSN-7. High selectivity of α-methylstyrene showed the important role of Lewis acid sites in these bifunctional catalysts. In spite of the coke formation in the Pt/HAlMSN catalysts, the reactivation recovered the activity of catalysts after 100 h of reaction. The molar coefficient absorbances of Pt/HAlMSN were measured using pyridine followed by water adsorption monitored by FTIR.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

High activity of aluminated bifunctional mesoporous silica nanoparticles for cumene hydrocracking and measurement of molar absorption coefficient

et al. 2015

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“…Several researchers have adopted various in situ and ex situ synthesis techniques to develop thermally and mechanically strong mesoporous materials. − Within the domain of aluminosilicate mesophase materials, surfactants employed in “bottom up” approaches were extensively explored to prepare meso/microcomposite materials by utilizing microporous molecular sieve seeds. , These amendments enhanced the thermal/mechanical stability and also provided excellent catalytic activity in several organic transformations such as esterification, cracking, acylation, and synthesis of α-tocopherol . These established landmarks in the field of aluminosilicate mesoporous materials motivated researchers to focus on the synthesis of framework materials similar to silicoaluminophosphate. − ,, Numerous methods like the liquid crystal templating (LCT) mechanism, cooperative self-assembly, , acid–base pair, sol–gel, and solvent-free synthetic routes have been used to synthesize mesoporous AlPO. Nevertheless, the lack of long-range order, owing to imperfect crystallization and poor condensation of inorganic moieties like Al, P, and Si around micelle aggregates of the surfactant makes the AlPO-based mesophase lamellar.…”

Section: Introductionmentioning

confidence: 99%

“…31 These established landmarks in the field of aluminosilicate mesoporous materials motivated researchers to focus on the synthesis of framework materials similar to silicoaluminophosphate. [4][5][6][7][8][9][10][11]32,33 Numerous methods like the liquid crystal templating (LCT) 34 mechanism, cooperative selfassembly, 35,36 acid−base pair, 37 sol−gel, 38 and solvent-free 39 synthetic routes have been used to synthesize mesoporous AlPO. Nevertheless, the lack of long-range order, owing to imperfect crystallization and poor condensation of inorganic moieties like Al, P, and Si around micelle aggregates of the surfactant makes the AlPO-based mesophase lamellar.…”

Section: ■ Introductionmentioning

confidence: 99%

Uniform Mesoporous Silicoaluminophosphate Derived by Vapor Phase Treatment: Its Catalytic and Kinetic Studies in Hydroisomerization of 1-Octene

et al. 2014

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Ordered mesoporous silicoaluminophosphate (MESO-SAPO-34) assembled from microporous SAPO-34 precursor was stabilized by post synthesis vapor phase treatment. The resultant MESO-SAPO-34 possessed uniform mesoporosity, high surface area, pore volume, and strong acidity. The resultant materials were studied as catalysts for the hydroisomerization of 1-octene and showed excellent conversion, and a maximum branched isomer selectivity of about 52% was achieved at low weight hourly space velocity (WHSV). Kinetic models based on Langmuir–Hinshelwood–Hougen–Watson (LHHW) mechanism were developed to describe the hydroisomerization of 1-octene, and the kinetics and adsorption parameters were estimated. A nonlinear regression based on modified Levenberg–Marquardt algorithm was used to estimate the parameters, and the model values were found to compare well with the experimental values. Parameters obtained from the LHHW model show that the conversion of 1-octene to other linear octenes requires low activation energy, whereas the conversion of linear octene to branched octene demands the highest activation energy. The enthalpy and entropy of adsorption obtained from Arrhenius plots were found to be consistent with thermodynamics.

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High population and dispersion of pentacoordinated AlV species on the surface of flame-made amorphous silica-alumina

Wang

Jiang

et al. 2019

Science Bulletin

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The dispersion and coordination of aluminium species on the surface of silica-alumina based materials are essential for controlling their catalytic activity and selectivity. Al IV and Al VI are two common coordinations of Al species in the silica network and alumina phase, respectively. Al V is rare in nature and was found hitherto only in the alumina phase or interfaces containing alumina, a behavior which negatively affects the dispersion, population, and accessibility of Al V species on the silica-alumina surface. This constraint has limited the development of silicaalumina based catalysts, particularly because Al V had been confirmed to act as a highly active center for acid reactions and single-atom catalysts. Here, we report the direct observation of high population of homogenously dispersed Al V species in amorphous silica-alumina in the absence of any bulk alumina phase, by high resolution TEM/EDX and high magnetic-field MAS NMR. Solid-state 27 Al multi-quantum MAS NMR experiments prove unambiguously that most of the Al V species formed independently from the alumina phase and are accessible on the surface for guest molecules. These species are mainly transferred to Al VI species with partial formation of Al IV species after adsorption of water. The NMR chemical shifts and their coordination transformation with and without water adsorption are matching that obtained in DFT calculations of the predicted clusters. The discovery presented in this study not only provides fundamental knowledge of the nature of aluminum coordination, but also paves the way for developing highly efficient catalysts.

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Synthesis of mesoporous aluminophosphates-based materials using various copolymers as templates

Cited by 3 publications

References 22 publications

High activity of aluminated bifunctional mesoporous silica nanoparticles for cumene hydrocracking and measurement of molar absorption coefficient

High activity of aluminated bifunctional mesoporous silica nanoparticles for cumene hydrocracking and measurement of molar absorption coefficient

Uniform Mesoporous Silicoaluminophosphate Derived by Vapor Phase Treatment: Its Catalytic and Kinetic Studies in Hydroisomerization of 1-Octene

High population and dispersion of pentacoordinated AlV species on the surface of flame-made amorphous silica-alumina

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