Comprehensive IR study on acid/base properties of metal oxides

Tamura, Masazumi; Shimizu, Ken‐ichi; Satsuma, Atsushi

doi:10.1016/j.apcata.2012.05.008

Cited by 333 publications

(276 citation statements)

References 51 publications

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“…The carbonyl stretching band of the acetamide on CeO 2 appeared at lower wavenumber than that on SiO 2 , indicating a weakened C=O bond strength in acetamide species on CeO 2 . Combined with the fact that CeO 2 has no Brønsted acid sites, 7 it is found that carbonyl oxygen of acetamide interacts with a Lewis acid site (Ce cation) on CeO 2 (Scheme 9). 23 Second, IR spectra of adsorbed n-butylamine on CeO 2 and SiO 2 were compared.…”

Section: ç Reaction Mechanismmentioning

confidence: 99%

“…Based on a systematic study of acidbase properties of various metal oxides, we have recently found that CeO 2 is characterized as a metal oxide with weak Lewis acid sites and strong base sites. 7 Expecting that a unique combination of the weak Lewis acidity, strong basicity, and redox properties of CeO 2 leads to unexplored catalytic properties, we have investigated various organic reactions by CeO 2 and have found that various nitrile transformation reactions (Schemes 1a1c) and transamidation (Scheme 1d) are effectively catalyzed by CeO 2 at low temperatures (30160°C) in liquid phase. 8 In this highlight review, we summarize our recent work on these catalytic systems.…”

Section: ç Introductionmentioning

confidence: 99%

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CeO2-catalyzed Transformations of Nitriles and Amides

2012

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Recently, cerium oxides have been extensively used as heterogeneous catalysts for green organic reactions. This review describes recent progress in such reactions, with a focus on our studies on pure CeO 2 -catalyzed reactions of nitriles and amides with nucleophiles (H 2 O, alcohols, and amines). Hydration of nitriles to amides in water, one-pot ester synthesis from nitriles and alcohols, one-pot synthesis of N-alkylamides from nitriles with amines, and synthesis of N-alkylamides from amides and amines (transamidation) are selectively catalyzed by CeO 2 under aqueous or solvent-free conditions. Mechanistic studies suggest that a cooperation of Lewis acid site (Ce 4+ cation) and acidbase (CeO) pair site plays essential roles in the catalytic reactions.

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Section: ç Reaction Mechanismmentioning

confidence: 99%

Section: ç Introductionmentioning

confidence: 99%

CeO2-catalyzed Transformations of Nitriles and Amides

2012

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“…Furthermore, basicity features of catalyst samples were investigated through IR measurements from CHCl 3 adsorption, [45,46] Figure S18. Subtle differences in the CHCl 3 stretching intensities were observed among samples.…”

Section: Mg Simentioning

confidence: 99%

“…CHCl3 was used as molecule probe for basicity evaluation. [45] Samples were exposed to CHCl3 at 20 ºC. MgO (Sigma-Aldrich) was evaluated for comparison.…”

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confidence: 99%

Ethanol to 1,3‐Butadiene Conversion by using ZrZn‐Containing MgO/SiO₂ Systems Prepared by Co‐precipitation and Effect of Catalyst Acidity Modification

et al. 2016

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Abstract:The conversion of ethanol to 1,3-butadiene (1,3-BD) has been investigated over ZrO2 and ZnO containing magnesia silica oxides prepared by co-precipitation method at different Mg-to-Si molar ratios. The effect of reaction temperature and ethanol flow rate was investigated. The catalyst acidity was modified through the addition of alkali metals (Na, K and Li) to the final materials. Catalysts were characterised by nitrogen physisorption analysis, Xray diffraction, scanning electron microscopy with energy dispersive X-ray, temperature programmed desorption of ammonia, infrared spectroscopy and 29 Si/( 7 Li) NMR spectroscopy. The catalytic results showed that the controlled reduction of catalyst acidity allows suppressing of ethanol dehydration, whilst increasing 1,3-BD selectivity. The best catalytic performance achieved 72 mol % for the combined 1,3-BD and acetaldehyde selectivity.

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“…The Py-FTIR technique allows quantifying Brønsted and Lewis acid sites, following the aforementioned procedure [45][46][47]. The surface concentration (q s-Py ) of the Brønsted ( B-Py ) and Lewis ( L-Py ) acid sites was calculated from the integration of IR bands centred at 1545 and 1450 cm −1 , respectively, using Equation (3) [45,[48][49][50][51].…”

Section: Ftir Spectroscopy Characterisation Of Zeolite Acidic Sites Bmentioning

confidence: 99%

Catalytic Ozonation of Toluene Using Chilean Natural Zeolite: The Key Role of Brønsted and Lewis Acid Sites

et al. 2018

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Abstract:The influence of surface physical-chemical characteristics of Chilean natural zeolite on the catalytic ozonation of toluene is presented in this article. Surface characteristics of natural zeolite were modified by acid treatment with hydrochloric acid and ion-exchange with ammonium sulphate. Prior to catalytic ozonation assays, natural and chemically modified zeolite samples were thermally treated at 623 and 823 K in order to enhance Brønsted and Lewis acid sites formation, respectively. Natural and modified zeolite samples were characterised by N 2 adsorption at 77 K, elemental analysis, X-ray fluorescence, and Fourier transform infrared (FTIR) spectroscopy, using pyridine as a probe molecule. The highest values of the reaction rate of toluene oxidation were observed when NH4Z1 and 2NH4Z1 zeolite samples were used. Those samples registered the highest density values of Lewis acid sites compared to other samples used here. Results indicate that the presence of strong Lewis acid sites at the 2NH4Z1 zeolite surface causes an increase in the reaction rate of toluene oxidation, confirming the role of Lewis acid sites during the catalytic ozonation of toluene at room temperature. Lewis acid sites decompose gaseous ozone into atomic oxygen, which reacts with the adsorbed toluene at Brønsted acid sites. On the other hand, no significant contribution of Brønsted acid sites on the reaction rate was registered when NH4Z1 and 2NH4Z1 zeolite samples were used.

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Comprehensive IR study on acid/base properties of metal oxides

Cited by 333 publications

References 51 publications

CeO2-catalyzed Transformations of Nitriles and Amides

CeO2-catalyzed Transformations of Nitriles and Amides

Ethanol to 1,3‐Butadiene Conversion by using ZrZn‐Containing MgO/SiO₂ Systems Prepared by Co‐precipitation and Effect of Catalyst Acidity Modification

Catalytic Ozonation of Toluene Using Chilean Natural Zeolite: The Key Role of Brønsted and Lewis Acid Sites

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Comprehensive IR study on acid/base properties of metal oxides

Cited by 333 publications

References 51 publications

CeO2-catalyzed Transformations of Nitriles and Amides

CeO2-catalyzed Transformations of Nitriles and Amides

Ethanol to 1,3‐Butadiene Conversion by using ZrZn‐Containing MgO/SiO2 Systems Prepared by Co‐precipitation and Effect of Catalyst Acidity Modification

Catalytic Ozonation of Toluene Using Chilean Natural Zeolite: The Key Role of Brønsted and Lewis Acid Sites

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Ethanol to 1,3‐Butadiene Conversion by using ZrZn‐Containing MgO/SiO₂ Systems Prepared by Co‐precipitation and Effect of Catalyst Acidity Modification