Selectivity aspects in the multi‐phase hydrogenation of α,β‐unsaturated aldehydes over supported noble metal catalysts: Part II

Satagopan, V.; Chandalia, Sampatraj B.

doi:10.1002/jctb.280600104

Cited by 26 publications

(9 citation statements)

References 1 publication

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“…The Rate of consumption /formation (kmol.m -3 . As explained earlier, the addition of the aqueous alkali together with the reaction mixture of cinnamaldehyde hydrogenation has shown to increase the selectivity towards cinnamyl alcohol [7,10,12,14,22]. Effect of changing KOH molarity in aqueous phase on overall conversion and selectivity is shown in Figure 8.…”

Section: Effect Of Catalyst Loadingmentioning

confidence: 73%

“…This implies the necessity for thorough study for different aspects affecting the selectivity of hydrogenation products of α,β-unsaturated aldehydes. Various authors have reviewed the different selectivity aspects for hydrogenation of unsaturated aldehydes [1,2,[5][6][7][8][9][10][11][12][13]. In general, hydrogenation of unsaturated aldehydes using platinum as catalyst gives unsaturated alcohols as the major product while use of palladium catalyst produces majorly saturated aldehydes [1].…”

Section: Introductionmentioning

confidence: 99%

“…The addition of the aqueous alkali together with the reaction mixture of cinnamaldehyde hydrogenation has shown to increase the selectivity towards cinnamyl alcohol [7,10,12,14,22], this leads to the formation of gas-liquid-liquid-solid, GLLS system. This promotion action by alkali cations can be explained on the grounds of two site adsorption mechanism.…”

Section: Introductionmentioning

confidence: 99%

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Kinetics of cinnamaldehyde hydrogenation in four phase system

Khan

Joshi

Ranade

2019

Chemical Engineering Journal

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The kinetics of cinnamaldehyde hydrogenation in four phase system viz. gas (hydrogen)-liquid (cinnamaldehyde + toluene)-liquid (aqueous KOH)-solid (catalyst, 5% Pt/C), [GLLS] system has been studied in this work. As reported, addition of aqueous alkali in hydrogenation of unsaturated aldehydes like cinnamaldehyde shifts selectivity towards unsaturated alcohol, cinnamyl alcohol. The promotion action by alkali metals for improving selectivity towards cinnamyl alcohol involves changes in the adsorption mechanism of the cinnamaldehyde in a way that C=O bond get preferentially hydrogenated. In cinnamaldehyde hydrogenation in presence of promoters two different catalytic sites can be considered, each for C=O and C=C bond hydrogenation. In accordance with this consideration and as demonstrated in various studies on hydrogenation of unsaturated aldehydes, further hydrogenation of intermediate-cinnamyl alcohol (C=C bond hydrogenation) occurs on Pt only sites while cinnamaldehyde and intermediate hydrocinnamaldehyde (both involving C=O bond hydrogenation) are hydrogenated on catalytic 2 sites affected by promoters. This preferential adsorption and hydrogenation through C=O bond leads to the increased selectivity of cinnamyl alcohol. Although, many authors have studied cinnamaldehyde hydrogenation using various promoters, there are very few reports on kinetics in which this two site approach behind promotion action has been considered. The effect of various operating parameters on the rates of hydrogenation was studied and the two site Langmuir-Hinshelwood type of kinetic model was used for evaluating the kinetic parameters by fitting experimental data. The thermodynamic model for estimating the solubility of hydrogen in the reaction mixture was incorporated with this kinetic model.

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Section: Effect Of Catalyst Loadingmentioning

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Kinetics of cinnamaldehyde hydrogenation in four phase system

Khan

Joshi

Ranade

2019

Chemical Engineering Journal

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“…Several other additives have been added to the catalyst to increase the selectivity to UOL. These additives, such as alkalis, Cr, and Cl, either acted as active sites or interacted with the support to generate new active sites for the activation of the CO bond. ,,,,,− With the addition of NaOH or KOH to the liquid solvent, the selectivity to COL and reaction rate were significantly increased. , The reasons are 2-fold: one is that OH – in the liquid phase inhibits the adsorption of the CC bond, and the other is the promotion of alkali cations. The latter mechanism is that Na + or K + on the surface of metal NPs acted as a Lewis site for the adsorption of the CO group .…”

Section: Selective Hydrogenation Of Ual To Uolmentioning

confidence: 99%

Highly Selective Catalysts for the Hydrogenation of Unsaturated Aldehydes: A Review

2020

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The selective hydrogenation of unsaturated aldehydes (UAL) to saturated aldehydes (SAL) and unsaturated alcohols (UOL) is an important industrial process for producing fine chemicals. More efforts were made on the selective hydrogenation of CO to UOL, because CC hydrogenation is thermodynamically favored over CO hydrogenation. A crucial step toward high selectivity is the rational design of heterogeneous catalysts. In this Review, the catalyst design for the hydrogenation of UAL to UOL are catalogued into three major strategies, namely, modifying electronic properties, forming electrophilic sites, and involving confinement/steric effect. Research works accomplished in the past decade on the catalyst design for UAL hydrogenation are systematically reviewed using the above strategies. The focus is on the selectivity-enhancing mechanism, methods to perform the chosen strategy, and the factors that influence the mechanism. Density functional theory calculations and catalyst stability are discussed to appreciate the challenges in designing catalysts. In addition, recent advances in the selective hydrogenation of CC of cinnamaldehyde to hydrocinnamaldehyde are briefly reviewed.

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“…Alkaline-aqueous organic biphasic systems have also been shown by a number of groups to enhance the selectivity for CNC double bond over palladium and CNO double bond over platinum. 28 Supercritical CO 2 has been studied as a solvent for selective reduction of cinnamaldehyde over platinum and although it can promote the selectivity towards cinnamylalcohol, the selectivity achieved is highly dependent on the reaction conditions. 29 In the present study, the use of heterogeneous carbon catalysts in ionic liquids is illustrated.…”

Section: Djmmentioning

confidence: 99%

Heterogeneously catalysed selective hydrogenation reactions in ionic liquids

Anderson¹,

Goodrich²,

Hardacre³

et al. 2003

Green Chem.

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The selective hydrogenation of a,b unsaturated aldehydes has been performed in a range of room temperature ionic liquids. The reaction data reported show that it is possible to enhance the selectivity of supported palladium catalysts for the reduction of the conjugated CNC bond by using ionic liquids as solvents compared with conventional molecular organic solvents. The catalyst system is easily recycled without the need to isolate or filter the catalyst and may be used without further treatment.

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Selectivity aspects in the multi‐phase hydrogenation of α,β‐unsaturated aldehydes over supported noble metal catalysts: Part II

Cited by 26 publications

References 1 publication

Kinetics of cinnamaldehyde hydrogenation in four phase system

Kinetics of cinnamaldehyde hydrogenation in four phase system

Highly Selective Catalysts for the Hydrogenation of Unsaturated Aldehydes: A Review

Heterogeneously catalysed selective hydrogenation reactions in ionic liquids

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