Zeolite Catalysts as Solid Solvents in Fine Chemicals Synthesis

Derouane, Éric G.; Crehan, Gabriel; Dillon, Christopher J.; Bethell, Donald; He, Hong; Hamid, Sharifah Bee Abd

doi:10.1006/jcat.2000.2933

Cited by 130 publications

(48 citation statements)

References 11 publications

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“…HPAs composed of W are more acidic than those composed of Mo. The thermal stability of hydrogen forms of HPAs changes with heteroatom, polyatom and polyanion structure as follows: H 3 …”

Section: Heteropoly Acids (Hpa)mentioning

confidence: 99%

“…Many solid catalysts have been traditionally synthesized in nano sizes per se or created as nano materials inside a porous matrix. A large number of inorganic oxides, mixed oxides, including alumina, silica, titania, zirconia, zeolites, and clays have been employed as both supports and catalysts [1][2][3][4][5][6]. Amongst them, clays have resurfaced to the fore as solid acids.…”

Section: Introductionmentioning

confidence: 99%

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Synergism of Clay and Heteropoly Acids as Nano-Catalysts for the Development of Green Processes with Potential Industrial Applications

Yadav

2005

Catal Surv Asia

132

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A large number of inorganic oxides, mixed oxides, including alumina, silica, titania, zirconia, zeolites, carbon, clays and ion exchange resins have been employed as both supports and solid acid catalysts. Clay structure collapses at high temperatures and has to be stablilized. The thermal stability and pore size issues were addressed by pillaring of clays. Natural clays are acid treated or ionexchanged to be used as solid acids, and the acidity and pore structure are dependent on the treatment methodology. Another important class of catalysts is the heteropoly acids (HPA), which are employed as homogeneous or heterogeneous catalysts, having both acid and redox properties. The focus of the current paper is to address the work done in our laboratory on the synergism between clays and heteropoly acids for the development of green processes. A comparison is also provided for the activity of these catalysts with other solid acids. Several alkylation, acylation, isomerization, condensation, dehydration, esterification, nitration and oxidation reactions which are useful in a wide spectrum of industries such as bulk, intermediates, dyes, plasticizer, pharmaceuticals, perfumes, flavours and other fine chemicals were investigated to improve the selectivity of the desired products.

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“…HPAs composed of W are more acidic than those composed of Mo. The thermal stability of hydrogen forms of HPAs changes with heteroatom, polyatom and polyanion structure as follows: H 3 …”

Section: Heteropoly Acids (Hpa)mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Synergism of Clay and Heteropoly Acids as Nano-Catalysts for the Development of Green Processes with Potential Industrial Applications

Yadav

2005

Catal Surv Asia

132

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“…This indicates that it is possible that preferential adsorption of the reactants or products onto the catalyst surface may be occurring. These effects have been noted previously for zeolite catalysts, when used for condensation reactions with liquid reactants, by Derouane et al [32,33].…”

Section: Meerwein-ponndorf-verley Reduction Of Benzaldehydementioning

confidence: 67%

“…Since we have shown that the enthalpy of adsorption is an important factor controlling the kinetics observed for MBOH decomposition, the hydrotalcites were studied as catalysts for a reaction in which the reactants and products have similar enthalpies of adsorption and, consequently, the adsorption enthalpies should not be expected to dominate the observed reaction rates. We have selected the Meerwein-Ponndorf-Verley (MPV) reduction of benzaldehyde using alcohols, since this reaction involves a simple hydrogen transfer MPV reduction has been well studied previously [11,12,[18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] [34,35] and is a useful model reaction concerning hydrogen transfer. In this paper, we present and contrast the results for the comparative study for the reaction of MBOH and benzaldehyde/alcohol mixtures.…”

Section: Introductionmentioning

confidence: 99%

Comments on the use of 2-methylbut-3-yn-2-ol decomposition as a probe reaction for the potential reactivity Mg?Al hydrotalcites as base catalysts

et al. 2005

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Mg:Al hydrotalcites (Mg:Al ratios 3:1, 3:2 and 4:1) have been characterised using the decomposition of 2-methylbut-3-yn-2-ol as a probe reaction for the acidic/basic properties. The hydrotalcites were used either as synthesised, or following calcination at 225 and 450°C. All gave almost exclusively of base-catalysed products (98-99%) and a very small amount of acid-catalysed products (1-2%). For this probe reaction only slight differences in reactivity to the probe molecule were observed. The materials were also investigated for the Meerwein-Ponndorf-Verley reduction of benzaldehyde using a range of primary and secondary alcohols. In contrast to the relative reactivity for the probe reaction, significant differences in both activity and selectivity were observed for the reduction of benzaldehyde. The materials calcined at 450°C were ca. 3 times more active on the basis of the initial rate of reaction compared with the non-calcined materials. Secondary alcohols were the most reactive and gave benzyl alcohol as the exclusive product, whereas primary alcohols also gave by-products due to ester formation and aldol condensation reactions and the structure of alcohol controlled the product selectivity in a manner consistent with the hydrogen donating properties of these alcohols. Consequently although the use of probe reactions can be instructive in determining the relative concentrations of acid and base sites, unfortunately relative reactivity profiles cannot be used predictively and this is discussed in terms of the adsorption of the probe reactant.

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“…Zeolites, with their unique acid properties and pore structures, exhibit good catalytic activity and selectivity in the acylation of aromatic compounds [3,14,15].…”

Section: Introductionmentioning

confidence: 99%

Effects of Modified Beta Zeolites with Acid on Anisole Acetylation in a Fixed Bed Reactor

2008

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A beta zeolite sample (Si/Al = 30) was modified by citric acid, tartaric acid, and hydrochloric acid. The catalytic performances of these zeolite together with another beta zeolite (Si/Al = 12.5) were tested in the anisole acetylation in a fixed-bed configuration. The zeolites were characterized by powder X-ray diffraction, FT-IR of adsorbed pyridine, and temperature programmed desorption of ammonia. The ratios of Si/Al, the specific surface areas, and the pore sizes were also measured. The results showed that the most active and stable behavior was achieved on the HCl treated zeolite. The strong acid sites as many as possible but with an appropriate concentration and strength were needed in order to obtain an optimum activity and stability.

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Zeolite Catalysts as Solid Solvents in Fine Chemicals Synthesis

Cited by 130 publications

References 11 publications

Synergism of Clay and Heteropoly Acids as Nano-Catalysts for the Development of Green Processes with Potential Industrial Applications

Synergism of Clay and Heteropoly Acids as Nano-Catalysts for the Development of Green Processes with Potential Industrial Applications

Comments on the use of 2-methylbut-3-yn-2-ol decomposition as a probe reaction for the potential reactivity Mg?Al hydrotalcites as base catalysts

Effects of Modified Beta Zeolites with Acid on Anisole Acetylation in a Fixed Bed Reactor

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