Transient experiments on the selective oxidation of methane to formaldehyde over V2O5/SiO2 studied in the temporal-analysis-of-products reactor

Kartheuser, B.; Hodnett, B.K.; Zanthoff, H.‐W.; Baerns, M.

doi:10.1007/bf00769472

Cited by 44 publications

(17 citation statements)

References 17 publications

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“…Ž . Alptekin et al, 1999 , RTOC data k rk , 0.00473 point red ox to a rate of catalyst oxidation much faster than that of reduc-Ž tion Kartheuser et al, 1993;Arena et al, 1994Arena et al, , 1997Mc-. Cormick et al, 1997;Arena et al, 2000 . Furthermore, Eq.…”

Section: њC 650њcmentioning

confidence: 99%

“…Then, as a consequence of marked differences in the reactivity of the silica samples, the addition of promoters might have either a positive or negative effect on the activity of the carrier. In particular, while V O pro- 2 5 Ž motes the reactivity of any silica samples Spencer and Pereira, 1989;Kennedy et al, 1992;Kartheuser et al, 1993;Parmaliana et al, 1993Parmaliana et al, , 1994Parmaliana et al, , 1995aKoranne et al, 1993Koranne et al, , . 1994Arena et al, 1995 . MoO enhances the performance 3 Ž of sol-gel and pyrolitic samples Spencer and Pereira, 1987;Sun et al, 1992;Mauti and Mims, 1993;Parmaliana et al, .…”

Section: Introductionmentioning

confidence: 99%

“…Parmaliana and Arena, 1997 . Although the many attempts to shed light on the nature of the active sites and reaction mechanism, the role of the cata-Ž . lyst lattice oxygen ions LOI in the CH activation and 4 Ž HCHO formation processes is still controversial Kennedy et al, 1992;Kartheuser et al, 1993;Mauti and Mims, 1993;Koranne et al, 1993Koranne et al, , 1994Parmaliana et al, 1993Parmaliana et al, , 1995aFaraldos et al, 1996;Arena et al, 1994Arena et al, , 1997Herman et al, . Ž 1997 .…”

Section: Introductionmentioning

confidence: 99%

“…In particular, isotopic labeling Koranne et al, 1993Koranne et al, , . Ž 1994Mauti andMims, 1993 andtransient techniques Kennedy et al, 1992;Kartheuser et al, 1993;Koranne et al, 1993Koranne et al, , 1994Parmaliana et al, 1994Parmaliana et al, , 1995aArena et al, 1994Arena et al, , . 1997Parmaliana and Arena, 1997 were used to probe the Ž .…”

Section: Introductionmentioning

confidence: 99%

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Kinetics of the partial oxidation of methane to formaldehyde on silica catalyst

Arena¹,

Frusteri²,

Parmaliana³

2000

AIChE Journal

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The kinetics of the partial oxidation of methane to formaldehyde MPO on a '' precipitated'' silica catalyst in the 500 ᎐ 800ЊC range was in®estigated. The influence of temperature and reaction mixture composition on the density of reduced sites of the catalyst under steady state was e®aluated by in situ reaction temperature oxygen chemisorption measurements. The kinetics of the MPO on silica is pseudo first and zero-order on P and P , respecti®ely, while the density of reduced sites depends C H o 4 2 upon the square root of the P rP ratio. The rate-determining step is the acti®ation C H O 4 2 ( y 1 ) of C ᎐ H bond of CH molecules E s 142 kJ ؒ mol , while oxygen replenishment 4 r e d ( y 1 ) is a nonacti®ated reaction step E f 20 kJ ؒ mol . A Langmuir-Hinshelwood kinetic o x model, accounting for a two-site-dissociati®e acti®ation mechanism of both CH and 4 O , thoroughly describes the steady state of the silica surface and the reaction kinetics 2 of the MPO in the 500 ᎐ 800ЊC range.

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Section: њC 650њcmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Kinetics of the partial oxidation of methane to formaldehyde on silica catalyst

Arena¹,

Frusteri²,

Parmaliana³

2000

AIChE Journal

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“…• a description of the interaction of small alkanes with metal oxides [114,115,119,122,124,127,131,132,140,149,158,160], with promoted metal oxides [108,120,122,123,129,145,153] or zeolites [116,121,122,141,144,146,151] • studies on the role of lattice oxygen in oxidation catalysis [110,113,124,134,137,162] • studies on selective catalytic reduction (SCR, DeNO x ) • studies on metal catalysts [108,151,153,156,157] • the development of mathematical models in TAP modeling [105, 112, 117-120, 135, 138].…”

Section: Parameter Molecular Beam Tap-1 Reactor System Laboratory Fixmentioning

confidence: 99%

Transient Catalytic Studies

Hinrichsen

2008

Handbook of Heterogeneous Catalysis

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The Importance of Transient Catalytic StudiesThe concept of using transient operations dates back to the late 1930s and the preliminary investigations conducted by Wagner and Hauffe [1,2]. Later, during the 1960s, Tamaru contributed substantially to this field in heterogeneous catalysis, in particular, by the use of the method of transient response [3] and by introducing the isotopic labeling technique [4]. Since then, transient methods have become standard tools for unraveling heterogeneously catalyzed reactions; for details, see the reviews in Refs. [5][6][7][8][9][10], monographs [11,12], and a special edition of Applied Catalysis [13]. The reasons for the wide application of transient methods are manifold. In chemical reactions, generally speaking, if the rate (rate equation, rate constant, and activation energy) of each of the elementary steps which comprise the overall reaction is known, the (micro)kinetics of the overall reaction may be understood. To take a simple example, in the reaction between hydrogen and bromine, the kinetics of the overall reaction follows a rather complicated rate law:However, if all the elementary reactions in the overall reaction are known, the kinetic behavior of the overall reaction may be explained on the basis of the rate constants, and the activation energies of the forward and backward reactions of the following elementary steps:In the case of such gas-phase reactions, the rate constants and activation energies of each of the elementary steps are independent of the concentration of reactants, reaction products, and reaction intermediates. This approximately also holds for reactions in solution.In the case of heterogeneously catalyzed reactions, the properties of the catalyst depend upon the concentrations of reactants, reaction intermediates, reaction products and, in some cases, spectator species that do not participate in the reaction path but which are chemisorbed on the catalyst surface. Furthermore, in many cases surface restructuring may occur along with the adsorption, and this results in marked changes in the reactivity of the surface. Consequently, even if the catalyst surface is kept in a well-defined state at the outset, as examined ex situ using a variety of spectroscopic techniques, it can be markedly different during the progress of reaction, and especially under industrially relevant reaction conditions. For example, in the case of oxide catalysts the extent of oxidation of the catalyst surface during the redox reaction is also influenced by the relative ratio of the rates of reduction and oxidation. This results in prominent changes in the properties of catalyst surfaces, depending upon the relative concentration of the reactants and the reaction temperature. In the case of acid catalysts, the acidity of the working catalyst surface (which should be associated with the catalytic activity) is that under the reaction conditions, and not that under the conditions far from those prevailing in the actual reaction.In the case of heterogeneous catalysis the rate co...

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Concepts in Selective Oxidation of Small Alkane Molecules

Schlögl

2009

Modern Heterogeneous Oxidation Catalysis

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Transient experiments on the selective oxidation of methane to formaldehyde over V2O5/SiO2 studied in the temporal-analysis-of-products reactor

Cited by 44 publications

References 17 publications

Kinetics of the partial oxidation of methane to formaldehyde on silica catalyst

Kinetics of the partial oxidation of methane to formaldehyde on silica catalyst

Transient Catalytic Studies

Concepts in Selective Oxidation of Small Alkane Molecules

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