A study on the stability of MCM-41-supported heteropoly acids under liquid- and gas-phase esterification conditions

Verhoef, Michel J.; Kooyman, Patricia J.; Peters, Joop A.; Bekkum, H. van

doi:10.1016/s1387-1811(98)00269-8

Cited by 169 publications

(70 citation statements)

References 19 publications

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“…The higher activity of HPA in the composite catalyst may be ascribed to a high dispersion of the HPA on NaY and MCM-41, providing more protons sites on the surface of composite than pure HPA. 54 Hence, it seems that the acidity of the NaY zeolite is effective for this reaction. These acid sites may be formed through the following mechanism: It is well documented that heteropoly acid species introduce into the channels of porous molecular sieves, which can be easily removed when the system is treated with polar solvents.…”

Section: Catalyst Behaviormentioning

confidence: 98%

Preparation of Heteropoly Acid/Porous Hybrid Materials and Investigation of their Catalytic Behavior in the Synthesis of Perimidine

Zendehdel

Mobinikhaledi

Alikhani

et al. 2010

J Chinese Chemical Soc

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A series of hybrid heteropoly acids (HPA) were prepared. The HPA/NaY and HPA/NaY/MCM-41 hybrids of the synthesized catalysts were characterized using XRD, BET, TGA, SEM and FT-IR techniques. The results show that reasonable amount of HPA in HPA/NaY and HPA/NaY/MCM-41 hybrids remains even after washing with water, which indicates that heteropoly anions were strongly bonded to the porous materials. The catalytic properties of the hybrid catalysts were examined for the preparation of 2-(4-nitrophenyl)-2,3-dihydro-1H-perimidine. The yield for perimidine by different catalysts was in order of HPA/NaY > HPA/NaY/MCM-41 > NaY > HPA > MCM-41.

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Section: Catalyst Behaviormentioning

confidence: 98%

Preparation of Heteropoly Acid/Porous Hybrid Materials and Investigation of their Catalytic Behavior in the Synthesis of Perimidine

Zendehdel

Mobinikhaledi

Alikhani

et al. 2010

J Chinese Chemical Soc

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“…However, the attachment of POMs to the mesopore walls takes place by means of very weak interaction of the POMs acidic protons with the silanol groups and gives rise to the leaching of the POMs when using these systems in polar solvents. Kozhevnikov and van Bekkum reported high catalytic activity of heteropoly acid-mesoporous systems for acid catalyzed reactions conducted in the liquid phase [45][46][47]. Nevertheless, they indicated that during the reactions involving polar media, POMs were delivered from mesopores and the catalytic reaction continued in homogeneous phase.…”

Section: Introductionmentioning

confidence: 99%

Encapsulation of Keggin-type phosphotungstic acid into the mesopores of SBA-16 as a reusable heterogeneous catalyst for the epoxidation of olefins

Masteri‐Farahani

Modarres

2017

Scientia Iranica

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Abstract. A heterogeneous catalyst for the epoxidation of ole ns was prepared by encapsulating Keggin-type phosphotungstic acid (H3PW12O40) into the mesopores of SBA-16. After the encapsulation, the pore entrance size of SBA-16 was reduced through a silylation method to encompass the catalyst in the mesopores and allow easy di usion of the reactants and products during the catalytic process. The prepared catalyst was characterized by FT-IR and Inductively Coupled Plasma-Optical Emission Spectroscopies(ICP-OES), X-Ray Di raction (XRD), and Transmission Electron Microscopy (TEM). The analysis results revealed that the mesoporous nature of SBA-16 was conserved after encapsulation of the catalyst following the silylation step. The catalytic activity of the prepared material was assessed in the epoxidation of ole ns with H2O2. The heterogeneous catalyst was recovered and reused up to ve cycles without considerable decrease in activity.

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“…Some of heterogeneous catalysts reported in the literature for esterification reactions include ion exchange resin, 2 H-ZSM-5, 3 zeolites-Y, 4 niobic acid, 5 sulphated oxides, 6 and heterpoly acids. Supported heterpoly acids (HPAs) 7 have been proved to be nearly comparable to sulphuric acid in their efficiency for a series of acid-catalyzed reactions in liquid phase. 8 Unfortunately, as HPAs are highly soluble in polar media, it is often difficult to separate them from the reaction mixture, which is problematic in industrial processes.…”

Section: Introductionmentioning

confidence: 99%

An Efficient and Green Approach for the Esterification of Aromatic Acids with Various Alcohols over H₃PO₄/TiO₂-ZrO₂

Kalbasi¹,

Massah²,

Barkhordari³

2010

Bulletin of the Korean Chemical Society

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TiO2-ZrO2 was prepared with surfactant through a sol-gel method. Catalysts containing 5 -35% H3PO4 were prepared using these oxides. Subsequently the catalytic performance of prepared catalysts was determined for liquid phase esterification of aromatic acids. H3PO4/TiO2-ZrO2 has been used as catalyst to synthesize various novel esters by esterification of some aromatic acids with aliphatic alcohols (2-propanol, 1-butanol, iso butanol, 3-pentanol, 1-hexanol, heptanol, cyclo heptanol, octanol and decanol). Under optimized conditions, maximum yields and selectivity (100%) to the corresponding ester, was obtained by using 25 wt % H3PO4/TiO2-ZrO2 as catalyst. The Catalyst can be easily recycled after reaction and can be reused without any significant loss of activity/selectivity performance. No by-product formation, high yields, short reaction times, mild reaction conditions, operational simplicity with reusability of the catalyst are the salient features of the present synthetic protocol. The reaction was carried out under solvent-free condition.

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A study on the stability of MCM-41-supported heteropoly acids under liquid- and gas-phase esterification conditions

Cited by 169 publications

References 19 publications

Preparation of Heteropoly Acid/Porous Hybrid Materials and Investigation of their Catalytic Behavior in the Synthesis of Perimidine

Preparation of Heteropoly Acid/Porous Hybrid Materials and Investigation of their Catalytic Behavior in the Synthesis of Perimidine

Encapsulation of Keggin-type phosphotungstic acid into the mesopores of SBA-16 as a reusable heterogeneous catalyst for the epoxidation of olefins

An Efficient and Green Approach for the Esterification of Aromatic Acids with Various Alcohols over H₃PO₄/TiO₂-ZrO₂

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A study on the stability of MCM-41-supported heteropoly acids under liquid- and gas-phase esterification conditions

Cited by 169 publications

References 19 publications

Preparation of Heteropoly Acid/Porous Hybrid Materials and Investigation of their Catalytic Behavior in the Synthesis of Perimidine

Preparation of Heteropoly Acid/Porous Hybrid Materials and Investigation of their Catalytic Behavior in the Synthesis of Perimidine

Encapsulation of Keggin-type phosphotungstic acid into the mesopores of SBA-16 as a reusable heterogeneous catalyst for the epoxidation of olefins

An Efficient and Green Approach for the Esterification of Aromatic Acids with Various Alcohols over H3PO4/TiO2-ZrO2

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An Efficient and Green Approach for the Esterification of Aromatic Acids with Various Alcohols over H₃PO₄/TiO₂-ZrO₂