Kinetics of aldolic reactions in the gaseous phase on solid catalysts of basic character

Malinowski, S.

doi:10.1016/0021-9517(63)90044-7

Cited by 18 publications

(8 citation statements)

References 3 publications

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“…While these values are quite low, they compare favorably to values determined for other solid-catalyzed aldol condensation reactions. 8,33 These results are also consistent with acetaldehyde temperature programmed desorption results on polycrystalline anatase and rutile TiO 2 34 as well as the TiO 2 (001) single-crystal surface 35 showing the aldol condensation products as desorption-limited features at 400-410 K.…”

Section: Resultssupporting

confidence: 82%

Kinetics, Selectivity, and Deactivation in the Aldol Condensation of Acetaldehyde on Anatase Titanium Dioxide

Rekoske

Barteau

2010

Ind. Eng. Chem. Res.

100

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Metal oxide catalysts are active for aldol condensation reactions of aldehydes and ketones but typically exhibit rapid deactivation. In this study, aldol condensation with dehydration of acetaldehyde to produce crotonaldehyde was catalyzed by oxidized TiO2 anatase. Particular emphasis was placed on determination of product selectivities and reaction kinetics as a function of both conversion and the extent of catalyst deactivation. Condensation of acetaldehyde is rapid and selective on anatase TiO2, with turnover frequencies exceeding 0.03 s−1 and crotonaldehyde selectivities approaching 100%. The main side reactions generating volatile products are: (a) hydrogenation of the reactant and product aldehydes, (b) a secondary cross-esterification between crotonaldehyde and acetaldehyde to form ethyl crotonate, and (c) secondary condensations involving crotonaldehyde. Catalyst deactivation was observed to affect both the rate of reaction and the product selectivities, particularly at low values of time-on-stream. Secondary condensations that deposit nonvolatile organic species on the catalyst surface are responsible for the initial deactivation of the catalyst. The catalyst mass increase during the course of reaction was observed to be directly proportional to the rate of deactivation. Selectivity patterns were impacted by deactivation in a manner that could not be explained solely by the changing conversion levels associated with the deactivation process. We conclude that deactivation during aldol condensation on the anatase polymorph of titania alters both activity and selectivity of the active sites. As a result, care must be taken to account for catalyst deactivation when comparing both catalytic activities and selectivities.

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Section: Resultssupporting

confidence: 82%

Kinetics, Selectivity, and Deactivation in the Aldol Condensation of Acetaldehyde on Anatase Titanium Dioxide

Rekoske

Barteau

2010

Ind. Eng. Chem. Res.

100

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“…At first sight, there is no appropriate acid or base site available for this transformation; however, similar reactions have been observed previously, for example Narayanan and Unnikrishnan 14 produced MIBK over a Ni/alumina catalyst, and there is literature confirming that silica can perform aldol condensation. 31,32 Therefore, we suggest that H atoms may spillover from the Pd and activate the silica (at higher temperatures the silica used did produce MO even with no Pd present (Jackson, S. D.; Gamman, J.; Wigzell, F. unpublished results)) to facilitate the aldol reaction to form MO which is then hydrogenated by the Pd to MIBK.…”

Section: Discussionmentioning

confidence: 90%

Synthesis of Methyl Isobutyl Ketone over Pd/MgO/SiO₂

Gamman

Jackson

Wigzell

2010

Ind. Eng. Chem. Res.

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In this paper, we have examined the activity and selectivity of catalysts for the one-step, gas phase production of methyl isobutyl ketone (MIBK) from acetone (propanone) over the temperature range 373-573 K. The catalysts used were an impregnated MgO/silica, a Pd-MgO/silica formed from coimpregnation of the nitrates, and a Pd supported on a 1% Mg doped silica, Pd/Mg-SiO 2 . Using MgO/silica, mesityl oxide (MO) was formed with 100% selectivity at 373 and 473 K. Addition of Pd gave 100% selectivity to MIBK at 373 K, albeit at low conversion. Pd-MgO/silica revealed a promotional effect of the MgO on the hydrogenation function of the Pd and a promotional effect of the Pd on the aldol condensation activity of the MgO. The Pd/Mg-SiO 2 catalyst showed high selectivity but low conversion, as no promoting effect was observed.

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“…Until now,r e-Scheme1.Expected reaction pathway of acrolein production starting from methanol and ethanol. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][21][22][23][24][25][26][27][28] Owing to the complexity of the process,f urtherr esearchi sn eededt ou nderstand the role of the acidity and basicity of the catalysts in such reactions and to clarify the reaction pathway.T he quantification of the acid/ base-site concentration and strength on the surface of oxide catalysts is even more crucial if the reactioni sp erformed in the presence of oxygen because it can lead to over-oxidation. [17b, 18-20, 24] The presence of basic sites is reported to be essentialt oi ncrease the activity and selectivity of the aldolization, butt heir strength also plays ar ole in eventual side reactions.…”

Section: Introductionmentioning

confidence: 99%

Influence of Catalyst Acid/Base Properties in Acrolein Production by Oxidative Coupling of Ethanol and Methanol

et al. 2017

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Oxidative coupling of methanol and ethanol represents a new route to produce acrolein. In this work, the overall reaction was decoupled in two steps, the oxidation and the aldolization, by using two consecutive reactors to investigate the role of the acid/base properties of silica-supported oxide catalysts. The oxidation of a mixture of methanol and ethanol to formaldehyde and acetaldehyde was performed over a FeMoO catalyst, and then the product mixture was transferred without intermediate separation to a second reactor, in which the aldol condensation and dehydration to acrolein were performed over the supported oxides. The impact of the acid/base properties on the selectivity towards acrolein was investigated under oxidizing conditions for the first time. The acid/base properties of the catalysts were investigated by NH -, SO -, and methanol-adsorption microcalorimetry. A MgO/SiO catalyst was the most active in acrolein production owing to an appropriate ratio of basic to acidic sites.

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Kinetics of aldolic reactions in the gaseous phase on solid catalysts of basic character

Cited by 18 publications

References 3 publications

Kinetics, Selectivity, and Deactivation in the Aldol Condensation of Acetaldehyde on Anatase Titanium Dioxide

Kinetics, Selectivity, and Deactivation in the Aldol Condensation of Acetaldehyde on Anatase Titanium Dioxide

Synthesis of Methyl Isobutyl Ketone over Pd/MgO/SiO₂

Influence of Catalyst Acid/Base Properties in Acrolein Production by Oxidative Coupling of Ethanol and Methanol

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Kinetics of aldolic reactions in the gaseous phase on solid catalysts of basic character

Cited by 18 publications

References 3 publications

Kinetics, Selectivity, and Deactivation in the Aldol Condensation of Acetaldehyde on Anatase Titanium Dioxide

Kinetics, Selectivity, and Deactivation in the Aldol Condensation of Acetaldehyde on Anatase Titanium Dioxide

Synthesis of Methyl Isobutyl Ketone over Pd/MgO/SiO2

Influence of Catalyst Acid/Base Properties in Acrolein Production by Oxidative Coupling of Ethanol and Methanol

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Synthesis of Methyl Isobutyl Ketone over Pd/MgO/SiO₂