Influence of Pore and Crystal Size of Crystalline Titanosilicates on Phenol Hydroxylation in Different Solvents

Wilkenhöner, Uwe; Langhendries, Gunther; Laar, Frederik van; Baron, Gino V.; Gammon, David W.; Jacobs, Pierre; Steen, Eric van

doi:10.1006/jcat.2001.3308

Cited by 123 publications

(66 citation statements)

References 17 publications

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“…Clerici [32] proposed that the intrinsic activity of titanium sites would decline progressively with increasing pore diameter. On the other hand, Wilkenhöner et al [6] observed that in comparison of TS-1 vs Al-free Ti-beta, smaller pore openings led to a decreased conversion with enhanced selectivity for HQ. Their study and van der Pol et al both concluded that phenol hydroxylation is controlled by diffusion [6,33].…”

Section: Resultsmentioning

confidence: 95%

“…Formation of the bulky five membered ring intermediate reduces the pore volume of TS-1 and, thus, imposes remarkable diffusion resistance of substrates upon TS-1 [5]. As a result, the catalytic performance of TS-1 is strongly affected by the molecular size of substrate and oxidant, nature of solvent, crystal size, pore structure and hydrophobicity [6,7].…”

Section: Introductionmentioning

confidence: 99%

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Phenol Hydroxylation over Alkaline Treated TS-1 Catalysts

Chao

Tsai

et al. 2009

Top Catal

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Alkaline treatment on TS-1 can selective remove silica from the framework while MFI zeolitic framework remains intact, which creates new large micropores or even mesopores and increases Si/Ti ratio in the alkaline treated TS-1. Among various alkaline hydroxide, CsOH treatment leads to partial destruction of MFI structure. All the desilicated TS-1 samples show enhanced phenol conversion and dihydroxylbenzene (DHB) yield in acetone solvent by two folds, which can be attributed to the higher Ti/Si ratio and improved diffusivity. Pore structure modified with alkaline treatment affects significantly reaction pathway and product selectivity. The initial product over the parent TS-1 and NaOH treated TS-1 is mainly 4-hydroxycyclohexa-2,5-dienone and catechol enriched DHB, respectively.

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Section: Resultsmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Phenol Hydroxylation over Alkaline Treated TS-1 Catalysts

Chao

Tsai

et al. 2009

Top Catal

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“…8). Comparing the catalytic activity of our catalysts with other metal encapsulated complexes in zeolite-Y analogues [46][47][48][49][50], our catalysts show lower conversation but superior selectivity towards catechol formation. Compared with TS-2, our catalysts (except Bi-based catalyst) are found to exhibit higher conversion of phenol (11-18 vs. 9.3%) [51], but lower than TS-1 [52][53][54].…”

Section: Catalytic Activity Studiesmentioning

confidence: 86%

Synthesis and Catalytic Activity of Cu(II), Fe(III) and Bi(III) Complexes of Thio-Schiff Base Encapsulated in Zeolite-Y for Hydroxylation of Phenol

Abbo

Titinchi

2009

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Coordination of 4-{[(1E)-(2-hydroxyphenyl) methylene]amino}-2,4-dihydro-3H-1,2,4-triazole-3-thione, [sal(thiotriazol)], with M-exchanged zeolite-Y (M = Cu(II), Fe(III) and Bi(III)) leads to the encapsulation of the metal complexes in the supercages of zeolite-Y by flexible ligand method. The prepared encapsulated metal complexes have been characterized by physico-chemical techniques, which indicated that the complexes were effectively encapsulated inside the supercages of Na-Y, without any modification of the morphology and structure of the zeolite. 3D model structure generated for these complexes suggests that zeolite-Y can accommodate these complexes in the FAU supercages without any strain. The catalytic activity of all the catalysts towards the hydroxylation of phenol was evaluated under heterogeneous conditions using hydrogen peroxide as an oxidant. Under the optimized conditions, these catalysts show moderate activity with excellent selectivity ([95%) towards catechol. These catalysts were stable in hydroxylation of phenol and have been reused a further three times after recovering. The results reflect the reusability of the catalysts, as no significant loss in their catalytic activity was noticed.

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“…It is also interesting that the selectivity of dihydroxybenzene decreases from 95.15% to 88.74% with the increasing phenol/H 2 O 2 ratio. This could be due to the high concentration of H 2 O 2 facilitating the generation of tar [15]. The amount of catalyst also strongly affects the products' distribution.…”

Section: Catalytic Activitymentioning

confidence: 99%

Diatomite as high performance and environmental friendly catalysts for phenol hydroxylation with H₂O₂

Jia

Han

Xiong

et al. 2007

Science and Technology of Advanced Materials

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A series of diatomite catalysts were treated and characterized. For the first time, the resulting materials were used in catalysis for the hydroxylation of phenol with H 2 O 2 and showed very high hydroxylation activity due to the Fe species in the diatomite. The effect of HCl treatment, contents of catalysts and H 2 O 2 were investigated and the active components of diatomite were discussed. The results show that diatomite is the promising candidate for industrial output due to their high catalytic activity, easy physical separation and very low costs. r

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Influence of Pore and Crystal Size of Crystalline Titanosilicates on Phenol Hydroxylation in Different Solvents

Cited by 123 publications

References 17 publications

Phenol Hydroxylation over Alkaline Treated TS-1 Catalysts

Phenol Hydroxylation over Alkaline Treated TS-1 Catalysts

Synthesis and Catalytic Activity of Cu(II), Fe(III) and Bi(III) Complexes of Thio-Schiff Base Encapsulated in Zeolite-Y for Hydroxylation of Phenol

Diatomite as high performance and environmental friendly catalysts for phenol hydroxylation with H₂O₂

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Influence of Pore and Crystal Size of Crystalline Titanosilicates on Phenol Hydroxylation in Different Solvents

Cited by 123 publications

References 17 publications

Phenol Hydroxylation over Alkaline Treated TS-1 Catalysts

Phenol Hydroxylation over Alkaline Treated TS-1 Catalysts

Synthesis and Catalytic Activity of Cu(II), Fe(III) and Bi(III) Complexes of Thio-Schiff Base Encapsulated in Zeolite-Y for Hydroxylation of Phenol

Diatomite as high performance and environmental friendly catalysts for phenol hydroxylation with H2O2

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Diatomite as high performance and environmental friendly catalysts for phenol hydroxylation with H₂O₂