Influence of basic properties of Mg,Al-mixed oxides on their catalytic activity in knoevenagel condensation between benzaldehyde and phenylsulfonylacetonitrile

Pérez, Caridad N.; Luiz, José Marques; Monteiro, Fontes; Manoel, José; Nieto, López; Henriques, Cristiane A.

doi:10.1590/s0100-40422009000900020

Cited by 20 publications

(13 citation statements)

References 37 publications

(62 reference statements)

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“…In this case, it is also associated with the temperature of catalyst pre-treatment (450 °C), but previously we observed the same results for Mg-Al mixed oxides pre-treated at higher temperature [19]. Total concentration of basic sites (CBS) was calculated as the total amount of CO 2 desorbed between 0 and 475 °C (Table 1) [29][30][31][32]. It is clearly seen that the intensity of desorption peak (concentration of basic sites) decreased with increasing Mg/Al molar ratio.…”

Section: Amount Of Basic Sitessupporting

confidence: 56%

“…CO 2 desorption peak was observed between 0 and 475 °C. This peak could be attributed to desorption of CO 2 from weak, medium and strong basic sites [29][30][31][32]. Another peak was observed above 475 °C (not shown in the figure) that have been attributed to desorption of CO 2 from the residual amorphous MgCO 3 phase that was not decomposed during the hydrotalcite thermal pre-treatment [33].…”

Section: Structure and Composition Of Hydrotalcite And Mg-al Mixed Oxmentioning

confidence: 91%

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Transesterification of rapeseed oil by Mg–Al mixed oxides with various Mg/Al molar ratio

Hájek

Kutálek

Smoláková

et al. 2015

Chemical Engineering Journal

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Section: Amount Of Basic Sitessupporting

confidence: 56%

Section: Structure and Composition Of Hydrotalcite And Mg-al Mixed Oxmentioning

confidence: 91%

Transesterification of rapeseed oil by Mg–Al mixed oxides with various Mg/Al molar ratio

Hájek

Kutálek

Smoláková

et al. 2015

Chemical Engineering Journal

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“…Actually, as shown by Ordóñez et al ., the substitution of Al 3+ by Fe 3+ in the structure of the resulting mixed oxide leads to a slight decrease in the concentration of basic sites and a more marked decrease in the concentration of acid sites. According to other studies, the acid sites are related to the presence of tetrahedrally coordinated Me 3+ ions in the crystalline structure. In the parent structure, Me 3+ ions are usually coordinated octahedrally.…”

Section: Resultsmentioning

confidence: 84%

Pyroaurite‐based MgFe mixed oxides and their activity in aldol condensation of furfural with acetone: effect of oxide composition

Kocík

Frolich

Perková

et al. 2018

J of Chemical Tech & Biotech

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Background Pyroaurite‐based MgFe oxides with varying Mg:Fe ratio were studied. The structural and acido‐basic properties were examined by number of experimental techniques. The oxide properties were correlated with the catalytic activity in aldol condensation of furfural with acetone. Results Well‐developed mesoporous structure was detected for all oxides. Peculiar continuous increase of concentration of basic sites and population of unsaturated strong basic O2− sites was observed with the rising amount of magnesium in the MgFe oxide matrix. A relatively higher concentration of Lewis acid Men+ sites was shown for low Mg:Fe ratios. Unambiguous correlation between conversion of furfural and the density of strong basic sites was proved by combined catalytic and statistical analysis. The contribution of other basic sites was found significantly less important. The impact of both acid and basic sites on the composition of reaction products was discussed. Conclusions MgFe oxides revealed good catalytic performance in the aldol condensation of furfural with acetone where samples with a high Mg:Fe ratio were significantly more basic and had relatively enhanced furfural conversion (nominal Mg:Fe ratio 10; furfural conversion 88% and selectivity to F2Ac 34%; reaction conditions: batch reactor; 50 °C; acetone/furfural = 10 mol L–1). © 2018 Society of Chemical Industry

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“…8,9 Nevertheless, the influence of the chemical composition of Mg−Al mixed oxides on the amount and the strength of their basic/acid sites as well as their catalytic performance is still a matter of discussion. 4,5,10,11 Considering the performance of Mg−Al mixed oxides in the condensation reactions, authors have generally reported that the activity increases with increasing both the total number of basic sites and their density. 5,10,11 In contrast, some authors 4 did not observe any clear relation between the activity and the basicity of Mg−Al mixed oxide.…”

Section: Synthetic Mg−al Hydrotalcites Have Chemical Compositions [M 2+mentioning

confidence: 99%

Influence of Mg–Al Mixed Oxide Compositions on Their Properties and Performance in Aldol Condensation

Kikhtyanin

Čapek

Smoláková

et al. 2017

Ind. Eng. Chem. Res.

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The influence of chemical composition of Mg−Al mixed oxides on their properties and catalytic performance in aldol condensation of furfural and acetone was studied. Pure alumina, Mg−Al layered double hydroxides with a wide range of Mg/Al molar ratios from 0.5 to 15, and pure magnesia were prepared by the same synthesis method, and corresponding oxides were produced by calcination of the as-prepared samples at T = 450 °C. The physicochemical properties of the samples were investigated by XRD, N 2 physisorption, SEM, CO 2 -TPD, and NH 3 -TPD, and their catalytic performance was evaluated in aldol condensation of furfural and acetone. SEM images revealed that the Al content in the samples influenced the size and the morphology of both large agglomerates and plate-like crystals. The CO 2 -TPD measurements proved that the concentration of basic sites and the distribution of their strengths was determined by the Mg/Al molar ratio in the Mg−Al mixed oxides. However, over the whole range of Mg/Al compositions studied here, no clear correlation between the chemical composition and the number and strength of basic sites was found. Nonetheless, the change in the strength and in the density of basic sites affected the catalytic performance of calcined Mg−Al mixed oxides. Additionally, morphology and crystal size also influenced the performance of the catalysts. Finally, the composition of reaction products was affected by acid−base and textural properties of the prepared Mg−Al-mixed oxides.

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Influence of basic properties of Mg,Al-mixed oxides on their catalytic activity in knoevenagel condensation between benzaldehyde and phenylsulfonylacetonitrile

Cited by 20 publications

References 37 publications

Transesterification of rapeseed oil by Mg–Al mixed oxides with various Mg/Al molar ratio

Transesterification of rapeseed oil by Mg–Al mixed oxides with various Mg/Al molar ratio

Pyroaurite‐based MgFe mixed oxides and their activity in aldol condensation of furfural with acetone: effect of oxide composition

Influence of Mg–Al Mixed Oxide Compositions on Their Properties and Performance in Aldol Condensation

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