Aldol condensation of benzaldehyde and heptanal: a comparative study of laboratory and industrially prepared Mg–Al mixed oxides

Vrbková, Eva; Tišler, Zdeněk; Vyskočilová, Eliška; Kadlec, David; Červený, Libor

doi:10.1002/jctb.5336

Cited by 19 publications

(11 citation statements)

References 22 publications

(35 reference statements)

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“…In the current work metal oxides have been applied as catalysts in aldol condensation of valeraldehyde with cyclopentanone. Since it is known that aldol condensation requires acids or bases as catalysts [15], basic supports such as CaO and MgO were modified with ceria and iron oxide, because of amphoteric nature of ceria and Lewis acidity of iron oxide. Therefore, not surprisingly, iron oxides have been used as catalysts in cyclohexanone aldol condensation [16], while cesium was utilized in aldol condensation of heptanal with benzaldehyde [17].…”

Section: List Of Symbolsmentioning

confidence: 99%

Aldol Condensation of Cyclopentanone with Valeraldehyde Over Metal Oxides

et al. 2019

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Kinetics of the cross aldol condensation of valeraldehyde with cyclopentanone was investigated in a batch reactor under atmospheric pressure at 130 °C using heterogeneous metal modified oxides, such as CeO 2 -MgO, FeO-MgO, FeO-CaO as well as pristine CaO as catalysts. The catalysts were prepared either by evaporation impregnation or deposition precipitation methods and characterized by XRD, TEM, SEM, nitrogen adsorption, ammonia and CO 2 TPD. The results revealed that an optimum amount of strong basic sites gives the highest ratio between cross condensation and self-condensation products of valeraldehyde. The highest yield of the desired product 2-pentylidenecyclopentanone (66%) was obtained with FeO-MgO prepared by the deposition precipitation methods. Graphical AbstractCross-condensation of valeraldehyde with cyclopentanone was investigated over heterogeneous Fe-CaO, CeO-MgO, FeO-CaO and CaO catalysts at 130 °C using cyclopentanone as a solvent and reactant. The highest yield of the desired product, 2-pentylidene-cyclopentanone, finding applications as fragrances, flavours and pharmaceuticals, was 66% obtained over FeO-MgO catalyst exhibiting both acid and basic sites.

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Section: List Of Symbolsmentioning

confidence: 99%

Aldol Condensation of Cyclopentanone with Valeraldehyde Over Metal Oxides

et al. 2019

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“…Alkaline earth metal oxides are generally known as heterogeneous basic catalysts, together with mixed Mg-Al oxides. 11,12 In this work, we have chosen several metal oxides and mixed metal oxides to catalyze aldol condensation of heptanal with cyclopentanone ( Table 5).…”

Section: Catalyst Preparationmentioning

confidence: 99%

Heterogeneous catalysts in the aldol condensation of heptanal with cyclopentanone

Vrbková

Kovářová

Vyskočilová

et al. 2019

Progress in Reaction Kinetics and Mechanism

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A large number of heterogeneous catalysts were tested in the aldol condensation of heptanal with cyclopentanone. There are many possible products from this aldol condensation, among which the most desired is 2-heptylidenecyclopentanone. As heterogeneous catalysts, the following were tested: caesium modified zeolites, functionalized MCM-41, and single (MgO, CaO, ZnO) and double (Mo–Si, Mg–Al, Zn–Al) metal oxides. The activity of modified zeolites and functionalized zeolites in this aldol condensation was low, whereas single and double metal oxides possessed high activity. The highest selectivity to the desired 2-heptylidenecyclopentanone (52%) was obtained using magnesium oxide as catalyst.

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“…CO 2 and H 2 O co-products were formed during the reactions in the fixed-bed reactor. CO 2 forms because of the 2-furoic acid decomposition, which is created by the Cannizzaro reaction from furfural [19]. H 2 O was formed during the dehydration of aldol products, mainly FCH-OH.…”

Section: Test No 1-rehydrated and Regenerated Lab Catalystmentioning

confidence: 99%

Aldol Condensation of Cyclohexanone and Furfural in Fixed-Bed Reactor

et al. 2019

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Aldol condensation reaction is usually catalysed using homogeneous catalysts. However, the heterogeneous catalysis offers interesting advantages and the possibility of cleaner biofuels production. Nowadays, one of the most used kinds of heterogeneous catalysts are hydrotalcites, which belong to a group of layered double hydroxides. This paper describes the aldol condensation of cyclohexanone (CH) and furfural (F) using Mg/Al mixed oxides and rehydrated mixed oxides in order to compare the catalyst activity after calcination and rehydration, as well as the possibility of its regeneration. The catalysts were synthesized by calcination and subsequent rehydration of the laboratory-prepared and commercial hydrotalcites, with Mg:Al molar ratio of 3:1. Their structural and chemical properties were determined by several analytical methods (inductively coupled plasma analysis (ICP), X-ray diffraction (XRD), diffuse reflectance infrared Fourier transform spectroscopy (DRIFT), specific surface area (BET), thermogravimetric analysis (TGA), temperature programmed desorption (TPD)). F-CH aldol condensation was performed in a continuous fixed-bed reactor at 80 °C, CH:F = 5:1, WHSV 2 h−1. The rehydrated laboratory-prepared catalysts showed a 100% furfural conversion for more than 55 h, in contrast to the calcined ones (only 24 h). The yield of condensation products FCH and F2CH was up to 68% and 10%, respectively. Obtained results suggest that Mg/Al mixed oxides-based heterogeneous catalyst is suitable for use in the aldol condensation reaction of furfural and cyclohexanone in a fixed-bed reactor, which is an interesting alternative way to obtain biofuels from renewable sources.

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Aldol condensation of benzaldehyde and heptanal: a comparative study of laboratory and industrially prepared Mg–Al mixed oxides

Cited by 19 publications

References 22 publications

Aldol Condensation of Cyclopentanone with Valeraldehyde Over Metal Oxides

Aldol Condensation of Cyclopentanone with Valeraldehyde Over Metal Oxides

Heterogeneous catalysts in the aldol condensation of heptanal with cyclopentanone

Aldol Condensation of Cyclohexanone and Furfural in Fixed-Bed Reactor

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