Michel Forissier - Academia.edu (original) (raw)

Papers by Michel Forissier

Industrial & Engineering Chemistry Process Design and Development, 1985

Composition modulation has been studied by the oxidation of propylene to acrolein over a catalyst... more Composition modulation has been studied by the oxidation of propylene to acrolein over a catalyst composed of a solid solution of antimony oxide in tin oxide. Modulation consists of periodically varying the partial pressures of propylene and oxygen in a square wave pattern so as to maintain a constant time-averaged feed composition. Half-periods were of equal duration. Selectivity to acrolein was found to increase substantlalty, but dependence of the increase on amplitude and period coukl not be ascertained. Yield of acrolein decreased with,composition modulation compared with steady-state operation at the same mean feed composition. Amplitude of the square wave was found to be important, but period affected the results just slightly. Product changes with time following a composition switch are used to comment critically on reaction pathway and rate-controlling step proposals in the literature.

L'aventure des premiers trolleybus à perche de France : de Tassin-la-Demi-Lune à Charbonnières-les-Bains, 1905-1907 / Michel Forissier & Jean-Pierre Petiot ; avec la collaboration amicale de François André Pietraforte

Kinetics of CO2 hydrogenation into methanol on a Cu-Zn-Al oxide catalyst

Bulletin De La Societe Chimique De France, 1985

Etude cinetique de la reaction d'hydrogenation de CO 2 et methanol sur un catalyseur oxyde Cu... more Etude cinetique de la reaction d'hydrogenation de CO 2 et methanol sur un catalyseur oxyde Cu-Zn-Al dans un reacteur differentielle a la pression atmospherique a 440°K. Etablissement d'une equation representant la vitesse de formation du methanol. Elaboration d'un certain nombre de mecanismes possibles et calcul des modeles qui en decoulent en suivant les lois de Langmuir-Hinshelwood

Applied Catalysis, 1985

The surface composition of Sb-Sn-0 mixed catalysts has been investigated by Auger electron spectr... more The surface composition of Sb-Sn-0 mixed catalysts has been investigated by Auger electron spectrometry. The results show a surface enrichment in antimony upon calcination, which is consistent with previous XPS analysis, AES can therefore be used to study the surface of real catalysts, provided a low intensity for the primary beam is used. The selectivity for the oxidation of propene to acrolein changes with the temperature at which the reaction is performed, and the variations depend on the temperature of the calcination step in the preparation of the catalyst. Two classes of catalysts appear: those calcined at 773 K exhibit, as with Sn02 samples, a decrease in selectivity for acrolein when the reaction temperature increases; those calcined at 1023 K and above show, as with Sb204, an increase in selectivity when the reaction temperature increases. The previous hypothesis that the active phase is an oriented film of Sb204 on the Sb-Sn02 solid solution agrees with this observation. Substantial differences are observed when comparing the selectivity pattern for the allylic oxidation of propene obtained in this work to that of allylic oxidations of butenes and o-xylene described in previous articles. This experimental fact is discussed in terms of different structure sensitivities for these reactions.

Applied Catalysis, 1990

A polycrystalline Fe-Ni ribbon exhibits catalytic properties c~fferent from those expected in 1H2... more A polycrystalline Fe-Ni ribbon exhibits catalytic properties c~fferent from those expected in 1H2-2H 2 equilibration, benzene hydrogenation and 1H-2H ex~ange, hydrogenation of carbon monoxide and oxidation of propene. This behavio~_r ~ e~pl~Sned by the composition of the surface ~aye~s, which undergo drastic changes during pretreatment and catalytic reactions.

Calorimetric study of oxygen bond strength in the surface layer of manganese dioxide

Reaction Kinetics and Catalysis Letters, 1977

The heat of oxygen removal from the MnO2 surface (q′s) during its reduction by carbon monoxide an... more The heat of oxygen removal from the MnO2 surface (q′s) during its reduction by carbon monoxide and the heat of reoxidation of the reduced surface by gaseous oxygen (qs) have been determined by a calorimetric method at 100 and 200°C. At 200°C both q′s and qs are close to the enthalpy of MnO2 transformation to Mn2O3. At 100°C the reduction of MnO2 takes place without any distinct formation of a phase of the lower oxide, however, it leads to significant changes in both the surface and the subsurface layer of the oxide.

Valence state and coordination number of molybdenum supported on SiO2 or MgO during the oxidation of propylene

Reaction Kinetics and Catalysis Letters, 1978

The nature of the species occurring during the oxidation of propylene on molybdenum oxides suppor... more The nature of the species occurring during the oxidation of propylene on molybdenum oxides supported on silica or magnesia has been investigated by diffuse reflectance spectroscopy. The reaction was performed in the uv cell itself. The oxidation occurs on partially reduced solids and the selectivity for acrolein is related to tetrahedral Mo5+.AbstractПрирода частиц, присутствующих при окислении пропилена на катализаторе окиси молибдена на носителях окиси кремния или окиси магния, была исследована с помощью диффузионной спектроскопии. Реакция осуществляется в самой УФ ячейке. Окисление протекает на частично восстановленной твердой фазе. Установлена связь между селективность№ для акролеина и тетраздрическим Mo+5.

Reaction Kinetics and Catalysis Letters, 1983

CD~ =CHCH~ was oxidized over silica supported molybdenum and vanadium oxide catalysts. The locati... more CD~ =CHCH~ was oxidized over silica supported molybdenum and vanadium oxide catalysts. The location of deuterium in the by-products propanol and 1,2-epoxypropane indicates that their formation proceeds through an attack of the carbon-carbon double bond in propene, and that 1,2-epoxypropane is an intermediate in the formation of propanol. CD: =CHCH 30lOtCaRnra Ha KaToJiH3aTopax OKHCYIOB MO/IH6,~eHa H BaHai, HaHeeeH-HblX Ha OKl.tCb anloMvI_mm. PacnonomeHI4e ,u.el:iTeprm B IIO6OtmhlX npo~,yKrax-npoHa-HaJie II 1,2-3iioKcHilponaHe-yKa3bmaeT Ha TO, qTO HX ofpa3oBaHHe IlpOTeKaeT qepe3 aTaKy ~BOflHOfi cBHaH IlpormneHa a trro 1,2-anoKcmlponaH ,.qB.ILqeTCR IlpoMe~KyTOqHbIM coe21rlHelLVieM o6pa3oBaHHR npoilnOHOBOrO aJIb,/IerHJIa.

Industrial & Engineering Chemistry Research, 1997

Energy & Fuels, 2002

A systematic experimental work for evaluating isothermality of a pilot reactor, flow regime, axia... more A systematic experimental work for evaluating isothermality of a pilot reactor, flow regime, axial dispersion, and mass transfer gradients between the catalyst surface and the bulk fluid in a trickle-bed hydrotreating reactor is presented. Experiments were carried out at the following operating conditions: 5.3 MPa total pressure, 356.2 mL mL-1 hydrogen-to-oil ratio, 613-653 K reaction temperature, and 1.0-2.5 h-1 liquid hourly space velocity. Commercial NiMo catalyst and feedstock were used for hydrotreating reactions. The catalyst (2.3 mm diameter) bed was diluted with silicon carbide (1.4 mm diameter) with an inert-to-catalyst volume ratio of 1. Various criteria reported in the literature were employed for evaluating axial dispersion in liquid and gas phases. Two typical tests were employed to determine mass transfer gradients: (1) changing the amount of catalyst loaded to the reactor and the feedstock flow rate at constant LHSV and (2) conducting experiments using different amounts of catalyst at variable LHSV.

Revue de Physique Appliquée, 1976

Materials Chemistry and Physics, 1985

The purpose of this survey is to presentrecentexperimental results and main ideas from our Labora... more The purpose of this survey is to presentrecentexperimental results and main ideas from our Laboratory in the field of metallic oxides. Structure sensitivity of oxidation reactions on simple oxides as Moo3 and Sb2Oq is clearlydemonstrated and is shown to depend on the surface atomic arrangements related to bulk structure, on the nature of the transition metal cations and on the chemical properties and size of the reactant molecules. Catalytic properties of isomorphous oxides as Sb2Moo6 and Bi2MoO6 or orthorhombic bronzes A~+M~M$~O62 with A=Sb or Bi and M=Mo or W are presented and discussed in terms of electron lone pair location, lattice oxygen lability and nature of transition metal ions. Extension is presented to multicomponent catalysts and a special emphasis is placed upon structural fitting between active phases and a support, and upon the importance of catalyst preparation conditions.

Catalysis Today, 1987

The sensitivity of partial oxidation reactions to the structure of the metallic oxides has been r... more The sensitivity of partial oxidation reactions to the structure of the metallic oxides has been recently demonstrated. It follows that surface atomic arrangements will strongly influence the catalytic properties. Consequently, the conditions of preparations and/or activation of a catalyst, the synergy effects observed in complex oxides, and the role of a support have all to be reconsidered with new eyes. Emphasis is therefore placed on structure sensitivity for oxide catalysts although other concepts still hold true. The catalytic properties of any catalyst depend on several parameters and particularly on its surface features. These include geometrical and chemical aspects which are obviously influenced by bulk features (ref. 6). In the case of oxides, lattice oxygen ions are directly involved in the mechanism of partial oxidation reactions, when a Mars and Van Krevelen type scheme is involved (ref. 7). The location and lability of such oxygen ions are thus important parameters to consider in relation to the catalytic properties of oxides. The lability of oxygen ions within the lattice is an important parameter in order to ensure high

Pseudochromatographic microanalysis utilizing gas-solid equilibria: Determination of NO2, NOCl, Cl2, HCl, CO2 and H20

Active Sites of V 2O 5/?-Al 2O 3Catalysts in the Oxidative Dehydrogenation of Ethane

J Catal, 1996

Étude des transferts de matière dans un réacteur triphasique gaz-liquide-solide, d'investigation cinétique (réacteur Robinson-Mahoney)

Http Www Theses Fr, 2001

Les procedes triphasiques gaz-liquide-solide sont largement utilises pour les reactions d'hyd... more Les procedes triphasiques gaz-liquide-solide sont largement utilises pour les reactions d'hydrotraitement. Le developpement de tels procedes impose une modelisation aussi precise que possible afin de limiter les experiences pilotes longues et couteuses. Cette modelisation necessite une connaissance approfondie de la cinetique des reactions. Elle requiert donc l'utilisation de reacteurs de laboratoire dedies a l'investigation cinetique tel que le reacteur Robinson-Mahoney. Ce dernier a ete concu pour offrir un bon contact entre les phases gaz et liquide d'une part et les phases solide et liquide d'autre part. Si ce reacteur presente certains avantages pour les etudes cinetiques (reacteur parfaitement agite), nous ne connaissons pas le domaine de conditions experimentales pour lequel le reacteur fonctionne effectivement en regime chimique. Ce travail a pour objet l'etude des transferts de matiere gaz-liquide et solide-liquide dans le reacteur Robinson-Mahoney. Nous avons selectionne les methodes d'absorption de gaz et de dissolution de solide pour mesurer le coefficient de transfert de matiere gaz-liquide, kLaL, et le coefficient de transfert de matiere solide-liquide, kS, respectivement. Pour chaque coefficient nous avons etudie l'influence de plusieurs parametres tels que la vitesse d'agitation ainsi que les proprietes du liquide. Dans le cas du transfert solide-liquide, nous nous sommes interesses a la relation entre kS et la vitesse du liquide. Enfin, nous avons propose une correlation pour l'estimation de kLaL et kS.

Chemischer Informationsdienst, 1976

Die Bindungsenergie zwischen Sauerstoff und partiell reduzierten Mo-Fe-Mischoxiden nimmt bei eise... more Die Bindungsenergie zwischen Sauerstoff und partiell reduzierten Mo-Fe-Mischoxiden nimmt bei eisenreichen Mischoxiden mit dem Grad der Reduktion zu, bei eisenarmen Mischoxiden ab und bleibt unver ändert bei Eisenmolybdat. Die Aktivit ät der Katalysatoren in bezug auf die Bildung von Acrolein aus Propen steht mit ihrem Reduktionsgrad in keinem einfachen Zusammenhang.

Correlation between X-ray photoelectron spectroscopy data and catalytic properties in selective oxidation on Sb-Sn-O catalysts

A detailed ESCA study of tin-antimony mixed oxides containing 1.5-39.7 atom Vertical Bar3< ant... more A detailed ESCA study of tin-antimony mixed oxides containing 1.5-39.7 atom Vertical Bar3< antimony and calcined at 500°⁻¹¹°°sup 0/C showed that the surface composition of catalysts containing Vertical Bar3; 5Vertical Bar3< antimony and all catalysts activated at 500°C corresponded to the bulk composition and consisted of solid solution of antimony(V) in SnOâ; and that surface enrichment with antimony (as an

Journal of Molecular Catalysis, 1992

A mechanism and rate expressions are proposed to explain the conversion kinetics of isobutyric ac... more A mechanism and rate expressions are proposed to explain the conversion kinetics of isobutyric acid to methacrylic acid by oxidative dehydrogenation on several iron phosphate catalysts. The relation between the catalyst nature and rate constants led us to suggest improvements in the catalysts and in reaction conditions. The mechanism proposed involves surface hydroxyl groups and sites composed of two nearby Fe cations. It corresponds to a new extension of the well-known Mars and Van Krevelen mechanism, often postulated for partial oxidation reactions on oxides.

Nature of the β-phase of bismuth molybdate

Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases, 1988

ABSTRACT

Industrial & Engineering Chemistry Process Design and Development, 1985

Composition modulation has been studied by the oxidation of propylene to acrolein over a catalyst... more Composition modulation has been studied by the oxidation of propylene to acrolein over a catalyst composed of a solid solution of antimony oxide in tin oxide. Modulation consists of periodically varying the partial pressures of propylene and oxygen in a square wave pattern so as to maintain a constant time-averaged feed composition. Half-periods were of equal duration. Selectivity to acrolein was found to increase substantlalty, but dependence of the increase on amplitude and period coukl not be ascertained. Yield of acrolein decreased with,composition modulation compared with steady-state operation at the same mean feed composition. Amplitude of the square wave was found to be important, but period affected the results just slightly. Product changes with time following a composition switch are used to comment critically on reaction pathway and rate-controlling step proposals in the literature.

L'aventure des premiers trolleybus à perche de France : de Tassin-la-Demi-Lune à Charbonnières-les-Bains, 1905-1907 / Michel Forissier & Jean-Pierre Petiot ; avec la collaboration amicale de François André Pietraforte

Kinetics of CO2 hydrogenation into methanol on a Cu-Zn-Al oxide catalyst

Bulletin De La Societe Chimique De France, 1985

Etude cinetique de la reaction d'hydrogenation de CO 2 et methanol sur un catalyseur oxyde Cu... more Etude cinetique de la reaction d'hydrogenation de CO 2 et methanol sur un catalyseur oxyde Cu-Zn-Al dans un reacteur differentielle a la pression atmospherique a 440°K. Etablissement d'une equation representant la vitesse de formation du methanol. Elaboration d'un certain nombre de mecanismes possibles et calcul des modeles qui en decoulent en suivant les lois de Langmuir-Hinshelwood

Applied Catalysis, 1985

The surface composition of Sb-Sn-0 mixed catalysts has been investigated by Auger electron spectr... more The surface composition of Sb-Sn-0 mixed catalysts has been investigated by Auger electron spectrometry. The results show a surface enrichment in antimony upon calcination, which is consistent with previous XPS analysis, AES can therefore be used to study the surface of real catalysts, provided a low intensity for the primary beam is used. The selectivity for the oxidation of propene to acrolein changes with the temperature at which the reaction is performed, and the variations depend on the temperature of the calcination step in the preparation of the catalyst. Two classes of catalysts appear: those calcined at 773 K exhibit, as with Sn02 samples, a decrease in selectivity for acrolein when the reaction temperature increases; those calcined at 1023 K and above show, as with Sb204, an increase in selectivity when the reaction temperature increases. The previous hypothesis that the active phase is an oriented film of Sb204 on the Sb-Sn02 solid solution agrees with this observation. Substantial differences are observed when comparing the selectivity pattern for the allylic oxidation of propene obtained in this work to that of allylic oxidations of butenes and o-xylene described in previous articles. This experimental fact is discussed in terms of different structure sensitivities for these reactions.

Applied Catalysis, 1990

A polycrystalline Fe-Ni ribbon exhibits catalytic properties c~fferent from those expected in 1H2... more A polycrystalline Fe-Ni ribbon exhibits catalytic properties c~fferent from those expected in 1H2-2H 2 equilibration, benzene hydrogenation and 1H-2H ex~ange, hydrogenation of carbon monoxide and oxidation of propene. This behavio~_r ~ e~pl~Sned by the composition of the surface ~aye~s, which undergo drastic changes during pretreatment and catalytic reactions.

Calorimetric study of oxygen bond strength in the surface layer of manganese dioxide

Reaction Kinetics and Catalysis Letters, 1977

The heat of oxygen removal from the MnO2 surface (q′s) during its reduction by carbon monoxide an... more The heat of oxygen removal from the MnO2 surface (q′s) during its reduction by carbon monoxide and the heat of reoxidation of the reduced surface by gaseous oxygen (qs) have been determined by a calorimetric method at 100 and 200°C. At 200°C both q′s and qs are close to the enthalpy of MnO2 transformation to Mn2O3. At 100°C the reduction of MnO2 takes place without any distinct formation of a phase of the lower oxide, however, it leads to significant changes in both the surface and the subsurface layer of the oxide.

Valence state and coordination number of molybdenum supported on SiO2 or MgO during the oxidation of propylene

Reaction Kinetics and Catalysis Letters, 1978

The nature of the species occurring during the oxidation of propylene on molybdenum oxides suppor... more The nature of the species occurring during the oxidation of propylene on molybdenum oxides supported on silica or magnesia has been investigated by diffuse reflectance spectroscopy. The reaction was performed in the uv cell itself. The oxidation occurs on partially reduced solids and the selectivity for acrolein is related to tetrahedral Mo5+.AbstractПрирода частиц, присутствующих при окислении пропилена на катализаторе окиси молибдена на носителях окиси кремния или окиси магния, была исследована с помощью диффузионной спектроскопии. Реакция осуществляется в самой УФ ячейке. Окисление протекает на частично восстановленной твердой фазе. Установлена связь между селективность№ для акролеина и тетраздрическим Mo+5.

Reaction Kinetics and Catalysis Letters, 1983

CD~ =CHCH~ was oxidized over silica supported molybdenum and vanadium oxide catalysts. The locati... more CD~ =CHCH~ was oxidized over silica supported molybdenum and vanadium oxide catalysts. The location of deuterium in the by-products propanol and 1,2-epoxypropane indicates that their formation proceeds through an attack of the carbon-carbon double bond in propene, and that 1,2-epoxypropane is an intermediate in the formation of propanol. CD: =CHCH 30lOtCaRnra Ha KaToJiH3aTopax OKHCYIOB MO/IH6,~eHa H BaHai, HaHeeeH-HblX Ha OKl.tCb anloMvI_mm. PacnonomeHI4e ,u.el:iTeprm B IIO6OtmhlX npo~,yKrax-npoHa-HaJie II 1,2-3iioKcHilponaHe-yKa3bmaeT Ha TO, qTO HX ofpa3oBaHHe IlpOTeKaeT qepe3 aTaKy ~BOflHOfi cBHaH IlpormneHa a trro 1,2-anoKcmlponaH ,.qB.ILqeTCR IlpoMe~KyTOqHbIM coe21rlHelLVieM o6pa3oBaHHR npoilnOHOBOrO aJIb,/IerHJIa.

Industrial & Engineering Chemistry Research, 1997

Energy & Fuels, 2002

A systematic experimental work for evaluating isothermality of a pilot reactor, flow regime, axia... more A systematic experimental work for evaluating isothermality of a pilot reactor, flow regime, axial dispersion, and mass transfer gradients between the catalyst surface and the bulk fluid in a trickle-bed hydrotreating reactor is presented. Experiments were carried out at the following operating conditions: 5.3 MPa total pressure, 356.2 mL mL-1 hydrogen-to-oil ratio, 613-653 K reaction temperature, and 1.0-2.5 h-1 liquid hourly space velocity. Commercial NiMo catalyst and feedstock were used for hydrotreating reactions. The catalyst (2.3 mm diameter) bed was diluted with silicon carbide (1.4 mm diameter) with an inert-to-catalyst volume ratio of 1. Various criteria reported in the literature were employed for evaluating axial dispersion in liquid and gas phases. Two typical tests were employed to determine mass transfer gradients: (1) changing the amount of catalyst loaded to the reactor and the feedstock flow rate at constant LHSV and (2) conducting experiments using different amounts of catalyst at variable LHSV.

Revue de Physique Appliquée, 1976

Materials Chemistry and Physics, 1985

The purpose of this survey is to presentrecentexperimental results and main ideas from our Labora... more The purpose of this survey is to presentrecentexperimental results and main ideas from our Laboratory in the field of metallic oxides. Structure sensitivity of oxidation reactions on simple oxides as Moo3 and Sb2Oq is clearlydemonstrated and is shown to depend on the surface atomic arrangements related to bulk structure, on the nature of the transition metal cations and on the chemical properties and size of the reactant molecules. Catalytic properties of isomorphous oxides as Sb2Moo6 and Bi2MoO6 or orthorhombic bronzes A~+M~M$~O62 with A=Sb or Bi and M=Mo or W are presented and discussed in terms of electron lone pair location, lattice oxygen lability and nature of transition metal ions. Extension is presented to multicomponent catalysts and a special emphasis is placed upon structural fitting between active phases and a support, and upon the importance of catalyst preparation conditions.

Catalysis Today, 1987

The sensitivity of partial oxidation reactions to the structure of the metallic oxides has been r... more The sensitivity of partial oxidation reactions to the structure of the metallic oxides has been recently demonstrated. It follows that surface atomic arrangements will strongly influence the catalytic properties. Consequently, the conditions of preparations and/or activation of a catalyst, the synergy effects observed in complex oxides, and the role of a support have all to be reconsidered with new eyes. Emphasis is therefore placed on structure sensitivity for oxide catalysts although other concepts still hold true. The catalytic properties of any catalyst depend on several parameters and particularly on its surface features. These include geometrical and chemical aspects which are obviously influenced by bulk features (ref. 6). In the case of oxides, lattice oxygen ions are directly involved in the mechanism of partial oxidation reactions, when a Mars and Van Krevelen type scheme is involved (ref. 7). The location and lability of such oxygen ions are thus important parameters to consider in relation to the catalytic properties of oxides. The lability of oxygen ions within the lattice is an important parameter in order to ensure high

Pseudochromatographic microanalysis utilizing gas-solid equilibria: Determination of NO2, NOCl, Cl2, HCl, CO2 and H20

Active Sites of V 2O 5/?-Al 2O 3Catalysts in the Oxidative Dehydrogenation of Ethane

J Catal, 1996

Étude des transferts de matière dans un réacteur triphasique gaz-liquide-solide, d'investigation cinétique (réacteur Robinson-Mahoney)

Http Www Theses Fr, 2001

Les procedes triphasiques gaz-liquide-solide sont largement utilises pour les reactions d'hyd... more Les procedes triphasiques gaz-liquide-solide sont largement utilises pour les reactions d'hydrotraitement. Le developpement de tels procedes impose une modelisation aussi precise que possible afin de limiter les experiences pilotes longues et couteuses. Cette modelisation necessite une connaissance approfondie de la cinetique des reactions. Elle requiert donc l'utilisation de reacteurs de laboratoire dedies a l'investigation cinetique tel que le reacteur Robinson-Mahoney. Ce dernier a ete concu pour offrir un bon contact entre les phases gaz et liquide d'une part et les phases solide et liquide d'autre part. Si ce reacteur presente certains avantages pour les etudes cinetiques (reacteur parfaitement agite), nous ne connaissons pas le domaine de conditions experimentales pour lequel le reacteur fonctionne effectivement en regime chimique. Ce travail a pour objet l'etude des transferts de matiere gaz-liquide et solide-liquide dans le reacteur Robinson-Mahoney. Nous avons selectionne les methodes d'absorption de gaz et de dissolution de solide pour mesurer le coefficient de transfert de matiere gaz-liquide, kLaL, et le coefficient de transfert de matiere solide-liquide, kS, respectivement. Pour chaque coefficient nous avons etudie l'influence de plusieurs parametres tels que la vitesse d'agitation ainsi que les proprietes du liquide. Dans le cas du transfert solide-liquide, nous nous sommes interesses a la relation entre kS et la vitesse du liquide. Enfin, nous avons propose une correlation pour l'estimation de kLaL et kS.

Chemischer Informationsdienst, 1976

Die Bindungsenergie zwischen Sauerstoff und partiell reduzierten Mo-Fe-Mischoxiden nimmt bei eise... more Die Bindungsenergie zwischen Sauerstoff und partiell reduzierten Mo-Fe-Mischoxiden nimmt bei eisenreichen Mischoxiden mit dem Grad der Reduktion zu, bei eisenarmen Mischoxiden ab und bleibt unver ändert bei Eisenmolybdat. Die Aktivit ät der Katalysatoren in bezug auf die Bildung von Acrolein aus Propen steht mit ihrem Reduktionsgrad in keinem einfachen Zusammenhang.

Correlation between X-ray photoelectron spectroscopy data and catalytic properties in selective oxidation on Sb-Sn-O catalysts

A detailed ESCA study of tin-antimony mixed oxides containing 1.5-39.7 atom Vertical Bar3< ant... more A detailed ESCA study of tin-antimony mixed oxides containing 1.5-39.7 atom Vertical Bar3< antimony and calcined at 500°⁻¹¹°°sup 0/C showed that the surface composition of catalysts containing Vertical Bar3; 5Vertical Bar3< antimony and all catalysts activated at 500°C corresponded to the bulk composition and consisted of solid solution of antimony(V) in SnOâ; and that surface enrichment with antimony (as an

Journal of Molecular Catalysis, 1992

A mechanism and rate expressions are proposed to explain the conversion kinetics of isobutyric ac... more A mechanism and rate expressions are proposed to explain the conversion kinetics of isobutyric acid to methacrylic acid by oxidative dehydrogenation on several iron phosphate catalysts. The relation between the catalyst nature and rate constants led us to suggest improvements in the catalysts and in reaction conditions. The mechanism proposed involves surface hydroxyl groups and sites composed of two nearby Fe cations. It corresponds to a new extension of the well-known Mars and Van Krevelen mechanism, often postulated for partial oxidation reactions on oxides.

Nature of the β-phase of bismuth molybdate

Journal of the Chemical Society, Faraday Transactions 1: Physical Chemistry in Condensed Phases, 1988

ABSTRACT