Reactions of Carboxylic Acids on Oxides

Pestman, Robert; Koster, R.M.; Pieterse, J.A.Z.; Ponec, V.

doi:10.1006/jcat.1997.1623

Cited by 142 publications

(111 citation statements)

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“…[31] They proposed that hydrogen was first bound at the metallic sites and then spilled over to reduce the acid, which was bound at defect sites in the oxide. [32,35,36] Kinetic studies by Rachmady and Vannice supported this mechanism as they demonstrated the reaction fits a Langmuir-Hinshelwood model for two reactants binding at two different types of site. [30,37] XRD analysis of our catalyst showed only metallic iron, and gave no evidence of the oxide (Fig.…”

Section: Mechanism Of Oleic Acid Hydrotreatment With Fe-msnmentioning

confidence: 86%

“…The strength of metal-oxygen bonds can be estimated from the heats of formation of the highest oxides of the metal. [35] For instance, Fe forms stronger metal-oxygen bonds than Ni, which favors decarbonylation over hydrodeoxygenation when supported on silica. [18,28] Thus, the capacity to form stronger bonds allows for longer retention times of the oxygenated intermediates, which prevents the reaction from stopping at the carbonyl stage and lead to higher hydrodeoxygenation products.…”

Section: Mechanism Of Oleic Acid Hydrotreatment With Fe-msnmentioning

confidence: 99%

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Supported iron nanoparticles for the hydrodeoxygenation of microalgal oil to green diesel

Kandel

Anderegg

Nelson

et al. 2014

Journal of Catalysis

140

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Iron nanoparticles supported on mesoporous silica nanoparticles (Fe-MSN) catalyze the hydrotreatment of fatty acids with high selectivity for hydrodeoxygenation over decarbonylation and hydrocracking. The catalysis is likely to involve a reverse Mars-Van Krevelen mechanism, in which the surface of iron is partially oxidized by the carboxylic groups of the substrate during the reaction. The strength of the metal-oxygen bonds that are formed affects the residence time of the reactants facilitating the successive conversion of carboxyl first into carbonyl and then into alcohol intermediates, thus dictating the selectivity of the process. The selectivity is also affected by the pretreatment of Fe-MSN, the more reduced the catalyst the higher the yield of hydrodeoxygenation product. Fe-MSN catalyzes the conversion of crude microalgal oil into dieselrange hydrocarbons. Disciplines Materials Chemistry | Other Chemistry | Physical ChemistryComments NOTICE: this is the author's version of a work that was accepted for publication in Journal of Catalysis. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reflected in this document. Changes may have been made to this work since it was submitted for publication. A definitive version was subsequently published in Journal of Catalysis, [314, (2014)

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Section: Mechanism Of Oleic Acid Hydrotreatment With Fe-msnmentioning

confidence: 86%

Section: Mechanism Of Oleic Acid Hydrotreatment With Fe-msnmentioning

confidence: 99%

Supported iron nanoparticles for the hydrodeoxygenation of microalgal oil to green diesel

Kandel

Anderegg

Nelson

et al. 2014

Journal of Catalysis

140

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show abstract

“…Furthermore, the study of acetic acid hydrogenation has attracted much attention during the past decades. Pestman et al [5][6][7] have accomplished a series of experiments to explore the reactions of carboxylic acids on oxides and the products they obtained from acetic acid are acetone and aldehyde. Studies conducted by Rachmady and Vannice indicated that Pt supported on oxides is a promising catalyst for acetic acid hydrogenation and a product distribution of 50 % ethanol, 30 % ethyl acetate and 20 % ethane can be acquired on TiO 2 supported Pt catalyst [8,9].…”

Section: Introductionmentioning

confidence: 99%

Effect of Sn Addition in Gas Phase Hydrogenation of Acetic Acid on Alumina Supported PtSn Catalysts

Zhang

et al. 2014

Catal Lett

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Alumina supported Pt, Sn and PtSn catalysts were prepared by impregnation and tested in the gas phase hydrogenation of acetic acid, and characterized by N 2 -physisorption, XRD, H 2 -TPR, H 2 -pulse chemisorption, H 2 -TPD, DRIFTS (diffuse reflectance infrared Fourier transform spectroscopy), XPS, electron microscopy techniques (TEM, HRTEM and EDX). Results show that Sn addition to Pt/Al 2 O 3 catalyst can improve the conversion of acetic acid and suppress the production of by-products, as well as enhance the selectivity towards ethanol. The optimization of activity and selectivity can be achieved by changing reaction temperature and pressure. Characterizations indicated that the better performance of PtSn/Al 2 O 3 catalyst is due to the formation of PtSn alloy and Pt-SnO x species.

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“…17,22 Previous work has shown that the reduction of fatty acids catalyzed by metal oxides involves two different sites: a hydrogen activation site corresponding to in situ formed metal and a metal oxide site that binds the carboxylic groups. 18,23,24 Ponec and co-workers suggested the strength of the metal− oxygen bonds was a key factor in determining the capacity of the oxides to bind and activate acids for their reduction and used the heat of formation per oxygen atom in the highest oxide as an indicator of bond strength. 23 They identified iron oxide as having an optimal metal−oxygen bond strength, which was sufficiently strong to bind carboxylates, yet weak enough to allow the bound oxygen to react and escape as water to regenerate the binding site.…”

mentioning

confidence: 99%

“…18,23,24 Ponec and co-workers suggested the strength of the metal− oxygen bonds was a key factor in determining the capacity of the oxides to bind and activate acids for their reduction and used the heat of formation per oxygen atom in the highest oxide as an indicator of bond strength. 23 They identified iron oxide as having an optimal metal−oxygen bond strength, which was sufficiently strong to bind carboxylates, yet weak enough to allow the bound oxygen to react and escape as water to regenerate the binding site. Because of the higher affinity of carboxylic acids for the surface of iron oxide 25−27 and the easier reduction of copper oxide to its metallic form, we considered producing a hybrid catalyst containing both metal oxides.…”

mentioning

confidence: 99%

Synergistic Interaction between Oxides of Copper and Iron for Production of Fatty Alcohols from Fatty Acids

et al. 2015

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The selective hydrogenation of fatty acids to fatty alcohols can be achieved under moderate conditions (180°C , 30 bar H2) by simultaneously supporting copper and iron oxides on mesoporous silica nanoparticles. The activity of the cosupported oxides is significantly higher than that of each supported metal oxide and of a physical mixture of both individually supported metal oxides. A strong interaction between both metal oxides is evident from dispersion, XRD, TPR, and acetic acid TPD measurements, which is likely responsible for the synergistic behavior of the catalyst. Copper oxide is reduced in situ to its metallic form and thereby activates hydrogen. It is proposed that hydrogen spills over to iron oxide where fatty acids bind and are selectively reduced to the alcohol. ABSTRACT: The selective hydrogenation of fatty acids to fatty alcohols can be achieved under moderate conditions (180°C, 30 bar H 2 ) by simultaneously supporting copper and iron oxides on mesoporous silica nanoparticles. The activity of the cosupported oxides is significantly higher than that of each supported metal oxide and of a physical mixture of both individually supported metal oxides. A strong interaction between both metal oxides is evident from dispersion, XRD, TPR, and acetic acid TPD measurements, which is likely responsible for the synergistic behavior of the catalyst. Copper oxide is reduced in situ to its metallic form and thereby activates hydrogen. It is proposed that hydrogen spills over to iron oxide where fatty acids bind and are selectively reduced to the alcohol.

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Reactions of Carboxylic Acids on Oxides

Cited by 142 publications

References 0 publications

Supported iron nanoparticles for the hydrodeoxygenation of microalgal oil to green diesel

Supported iron nanoparticles for the hydrodeoxygenation of microalgal oil to green diesel

Effect of Sn Addition in Gas Phase Hydrogenation of Acetic Acid on Alumina Supported PtSn Catalysts

Synergistic Interaction between Oxides of Copper and Iron for Production of Fatty Alcohols from Fatty Acids

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