Heterogenization of H6PMo9V3O40 and palladium acetate in VPI-5 and MCM-41 and their use in the catalytic oxidation of benzene to phenol

Passoni, Luís C.; Luna, Fernando J.; Wallau, Martin; Buffon, Regina; Schuchardt, Ulf

doi:10.1016/s1381-1169(98)00040-5

Cited by 37 publications

(14 citation statements)

References 13 publications

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“…The order of softness of heteropoly anions in aqueous solution has been estimated as follows: SiW 12 40 4-. Although heteropolyacids are used in many acid catalyzed reactions, they possess some major disadvantages such as, (i) low surface area, (ii) high solubility in polar solvents, which makes their separation from the reaction medium difficult and (iii) deactivation during the reaction [44,45]. In order to improve the catalytic performance of heteropolyacids, several attempts have been made to heterogenize them by dispersing on suitable supports like silica (SiO 2 ) [46][47][48][49], active carbons [50,51] and ion exchange resins [52].…”

Section: Introductionmentioning

confidence: 99%

Solid Acid Catalysts: Modification of Acid Sites and Effect on Activity and Selectivity Tuning in Various Reactions

2009

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The effects of acidity and variation in concentration of acid sites of dodecatungstophosphoric acid (DTP), supported DTP and montmorillonite-K catalysts were studied for various organic reactions such as the hydroxyalkylation of phenols to bisphenols, intramolecular rearrangement of benzyl phenyl ether (BPE) to 2-benzyl phenol (2-BP) and selective cleavage of tert-butyldimethylsilyl (TBDMS) ether into the corresponding alcohol. Both dodecatungstophosphoric acid (DTP) impregnated on silica (SiO 2 ) and montmorillonite catalysts showed the highest catalyst activity with 90-95% selectivity to bisphenol for the hydroxyalkylation of phenols to give bisphenol. Temperature Programmed Desorption (TPD) of ammonia and activity results of various catalysts showed that an appropriate combination of both strong and weak acidic sites in the catalyst was highly desirable for high bisphenol selectivity. A 10% DTP/SiO 2 catalyst was found to be highly selective for the cleavage of TBDMS ether into the corresponding alcohol at room temperature giving a high TON of 9.5 9 10 5 even after the 4th recycle. DTP was also found to be a promising solid acid catalyst for the intramolecular rearrangement of BPE giving 2-BP.

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Section: Introductionmentioning

confidence: 99%

Solid Acid Catalysts: Modification of Acid Sites and Effect on Activity and Selectivity Tuning in Various Reactions

2009

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“…Extensive 31 P MAS NMR studies show that a significant amount of 12-molybdophosphoric acid in high loadings remain as a crystalline form, which in low loadings there is a chemical interaction between the silica and HPAs and new species emerge [9]. Therefore, due to the high solubility of HPAs in water and organic solvents physically adsorbed HPAs on the surface of support can be easily leached out which act as a homogeneous catalyst rather than a heterogeneous one and the concept of catalyst recovery is lost [10,11]. Furthermore, at low loadings partial decomposition of Keggin type HPA takes place.…”

Section: Introductionmentioning

confidence: 99%

Immobilization of Keggin and Preyssler tungsten heteropolyacids on various functionalized silica

Tarlani

Abedini

Nemati

et al. 2006

Journal of Colloid and Interface Science

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“…[2,3] Better results were obtained using molecular oxygen in the presence of palladium and heteropolyacids. [4,5] Another alternative is the use of N 2 O over H-[Fe]-MFI or steamed H-[Al]-MFI zeolites. The surface a-oxygen, which is formed upon decomposition of N 2 O, was found to react with benzene to phenol, affording conversions of ca.…”

Section: Introductionmentioning

confidence: 99%

New Direct Hydroxylation of Benzene with Oxygen in the Presence of Hydrogen over Bifunctional Palladium/Platinum Catalysts

Laufer

Niederer

Hoelderich

2002

Advanced Synthesis & Catalysis

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Benzene can be hydroxylated directly to phenol with oxygen in the presence of hydrogen over Pt/Pd containing acid catalysts such as zeolites (BEA, MOR, FER, MFI), acid resins such as Amberlyst, or Nafion/silica composites. The best results were obtained over Nafion/silica composites. As main side products hydroquinone and catechol were found. Various reaction parameters and catalyst preparation methods were optimised.

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Heterogenization of H6PMo9V3O40 and palladium acetate in VPI-5 and MCM-41 and their use in the catalytic oxidation of benzene to phenol

Cited by 37 publications

References 13 publications

Solid Acid Catalysts: Modification of Acid Sites and Effect on Activity and Selectivity Tuning in Various Reactions

Solid Acid Catalysts: Modification of Acid Sites and Effect on Activity and Selectivity Tuning in Various Reactions

Immobilization of Keggin and Preyssler tungsten heteropolyacids on various functionalized silica

New Direct Hydroxylation of Benzene with Oxygen in the Presence of Hydrogen over Bifunctional Palladium/Platinum Catalysts

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